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'03 Cadillac CTS
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Discussion Starter #21
Time to disable the ABS system ( if that's possible ) and run the car normally for a few days and see if the problem persists.
It's a good idea in theory but in practice it's not going to work. Whether you 'unplug' the ABS unit or not the fluid is still going through it. So the only way it could be truly removed from the equation would be to make new lines and bypass the pump.

Unfortunately, the brake system is not designed to work that way. For one thing, there is no proportioning valve and for another - I really doubt the car would function at all, and if it did, you'd be introducing so many issues that it would probably not be able to be driven.

For myself, I've done my due diligence (and then some) and at some point a person has to weigh out what their time is worth and also if we're getting into a case of 'paralysis by analysis'.

We know it's not the master, we know it's not the calipers or hoses - that leaves exactly what? The only thing left is the pressure modulator. Given that the issue is intermittent and that's it related to pressure I'd have to say that the smart money is on the ABS pressure modulator :)

Hopefully the next one I order will survive the trip! :bonkers:
 

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well, there is one other possibility in the system, but it's rather unlikely, and it will quite possibly be changed together with the ABS unit anyway: the fluid.
 

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Discussion Starter #23
well, there is one other possibility in the system, but it's rather unlikely, and it will quite possibly be changed together with the ABS unit anyway: the fluid.
Agreed. It's unlikely but when I change the ABS pump I will flush the entire system. I tended to not factor in fluid too much in the equation - it's a fairly low mileage cream puff and I'm the only person that's touched the brakes on it (to date). I did check it to see what it looked like and it was quite clear and clean.

Hopefully the new ABS pump will arrive safe & sound without any shipping damage :bouncy:
 

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Cadillac CTS 2003, Pontiac Trans Am S.E. 1977
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When I think about the ABS, Traction Control System on this car, it reminds me of the GM commercial where Onstar sends a signal to the stolen truck and the engine stalls, then the brakes activate. I have had instances where TC has kicked on for unknown reasons and activated the ABS system to the point that all four wheels felt like they were at 70% braking power. Not only that, it cut my throttle connection and I could not accelerate, so I just sat there for 3-4 seconds until TC turned off and I could get out of the way; this happened in one of those situations where you wish you had 500HP so you could hurry up and get out of dodge.

I have not the read shop manual yet, but is not ABS, TC, and the transmission all connected together into some bigger stability system? I have had all sorts of weird things happen between all of these systems; for instance, a warm, dry, summer day leaving the neighborhood with a gentle throttle and TC kicking on and not letting the vehicle accelerate for 2 seconds; pulling up to a line of cars at a red-light, pushing on the brake pedal only to have a humming sound and the pedal PUSHING BACK with the brakes not applying; there was few instances where I would pull up to a stop sign and sit there for 3-4 seconds and attempt to pull off only to find out the transmission did not downshift and sat there in 4th gear and activated TC when I tried to pull off. TC went off after it finally shifted into 1st. When I sit at a red-light with my foot on the brake pedal, I can feel it pulsating.

When I took my CTS to the circuit I got a good feel for the TC system and how it operates in a sport conditions. The TC system is able to apply braking force to each individual wheel at different levels to keep the car in control. At the lapping day the TC light never came on, but I could feel the larger system, stabilitrak I think, activating and tugging at all four wheels(imagine your brakes being played like a trumpet). I had never felt this system activate before on the street. I did not disable TC at the event. On my vehicle TC has and will activate without a light coming on to tell you. If I am not mistaken, I do believe that on GM vehicles, stabilitrak is the large system that controls the car in emergency situations.

A car like this you need a computer to fix it.
 

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2003 CTS 3.2/2004 GTO/2004 GMC Yukon
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I don't think the ABS pump is the problem. Is the ABS light on? Are you getting any error messages on the DIC? These cars are known to have intermittant TC issues where the brakes apply themselves mysteriously because there is a fault in the system. Since you have an 03, turn the key to the on position and hit F1 and F6 together and see what codes, if any, come up on the screen. While you can not disable the ABS system, you can turn off the traction control system and see if the problem continues. I know it is intermittent, but I wouldn't go throwing money at parts until I know for sure what was wrong.
 

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Discussion Starter #26
I mentioned back in the original post - there were/are no codes present. Not one. It's probably the only Cadillac on the road without one ;-)

Your suggestion about turning off traction control is a good one but when I researched it I found that the traction control software works by first detecting rear wheel slip. Rear wheel slip is not present when the issue occurs. If it were traction control this is how it would present;

1) The traction control system first retards the spark timing in an effort to stop the rear wheel slip.
2) Failing that, the system then cuts fuel to the injectors
3) If that still doesn't stop the rear wheel slip then, in a last ditch effort, the TCS system applies the REAR brakes in an effort to stop the rear wheel spin.

So, traction control applies to the REAR brakes but before it gets to that point it first bogs the engine down. The issue we're seeing is intermittent application of the FRONT brakes. The rear brakes remain free and there's no tell-tale bogging down of the engine that one typically sees during TCS operation. So, the traction control system really doesn't apply to our situation but it was an interesting suggestion.

If the pump & the corresponding new fluid doesn't change anything then it's going to the dealer to get the ABS module software updated to whatever is the latest & greatest. Hopefully there has been revisions to it over the years :)

There's really very little left in the brake system other the brake pressure modulator and the ABS module itself that could cause this issue - pretty much everything else has been eliminated. Given that pressure is being applied/held to the front brakes on an intermittent basis I'm still leaning towards the pressure modulator. It's been ordered and it's going in - if for no other reason then to permanently take it out of the equation. Having said that, there's damn little else it can be other then a potential software issue with the ABS module itself. There's really nothing left after that.
 

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Discussion Starter #27 (Edited)
When I think about the ABS, Traction Control System on this car, it reminds me of the GM commercial where Onstar sends a signal to the stolen truck and the engine stalls, then the brakes activate. I have had instances where TC has kicked on for unknown reasons and activated the ABS system to the point that all four wheels felt like they were at 70% braking power. Not only that, it cut my throttle connection and I could not accelerate, so I just sat there for 3-4 seconds until TC turned off and I could get out of the way; this happened in one of those situations where you wish you had 500HP so you could hurry up and get out of dodge.

I have not the read shop manual yet, but is not ABS, TC, and the transmission all connected together into some bigger stability system? I have had all sorts of weird things happen between all of these systems; for instance, a warm, dry, summer day leaving the neighborhood with a gentle throttle and TC kicking on and not letting the vehicle accelerate for 2 seconds; pulling up to a line of cars at a red-light, pushing on the brake pedal only to have a humming sound and the pedal PUSHING BACK with the brakes not applying; there was few instances where I would pull up to a stop sign and sit there for 3-4 seconds and attempt to pull off only to find out the transmission did not downshift and sat there in 4th gear and activated TC when I tried to pull off. TC went off after it finally shifted into 1st. When I sit at a red-light with my foot on the brake pedal, I can feel it pulsating.
That definitely presents as a traction control issue (see my post above for how the system engages) in your case the engine seems to bog down and then the fun begins. That's the TCS software following it's flowchart - first reduce engine power and then as a last resort apply the rear brakes.

In our case, I've activated the TCS system several times during driving but it's always engaged when it should (although not when I would if I were the computer!). I've found it to be remarkably sensitive, if I boot it even the slightest amount coming off a light and turning right it will usually engage - which is correct. You raised an interesting point though, don't each of the ABS/TCS systems fall under the umbrella of the Stabilty System?

Your post got me thinking about the stability system so I cracked open the service manual. Check this out;

The stability system seems to operate based on 3 primary inputs, the steering wheel position, the speed of the vehicle, and the lateral (sideways) acceleration of the vehicle. If the stability system detects a yaw rate error it tries to fix it by applying differential pressure to the left or right front wheel. This is what I'm seeing - differential pressure being applied/held at the front wheels causing the front brakes to heat up.

However, I doubt that the software would continue to apply the brakes even if it the stability system was being (incorrectly) triggered. It would seem to be that the stability system would tell the ABS pressure modulator to apply the pressure to the front brakes - so we're back at square one. If the stability systems did (erroneously) do that then the pressure should be released once the system 'thinks' the car is back on track. However, in our case, pressure is still being applied. That's why I say we're back to the ABS pressure modulator. That's it's job whether it's activated by ABS, the Stability System or Traction control. Something is keeping the pressure on the fronts on an intermittent basis. No doubt about it - I'm more sure then ever we're on the right track.

Back to the stability system though, in theory it could be applying pressure to the front brakes. However, it uses steering wheel position (in my case the car was dead straight), speed of the vehicle (in my case normal highway speed and sometimes city speed) and lateral acceleration to determine when to engage (in my case I was going dead straight - no lateral forces at all). That being said, it should only engage when the car is loaded to the sides at speed. I did replace the steering wheel position sensor a few year back but paid very close attention to it's proper positioning. In any event, if for no other reason, it may be time to borrow my buddy's scan tool and read what the car thinks the steering wheel position is when it's straight (just to be 100% certain it's not off and eliminate it as a variable).

However, the next paragraph might be of interest to your situation. "When braking during VSES activation the pedal pulsations feel different then the ABS pedal pulsations. The brake pedal pulsates at a higher frequency during VSES activation." Perhaps that can help you to isolate which system is active when you pull up to the lights and get the pedal pushing back at you etc.

If I were experiencing your symptoms I'd scan for codes because with the way your problems are presenting there's probably codes present. It may well be one issue causing the whole lot of the symptoms. In fact, I'm almost sure it would be.
 

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That definitely presents as a traction control issue (see my post above for how the system engages) in your case the engine seems to bog down and then the fun begins. That's the TCS software following it's flowchart - first reduce engine power and then as a last resort apply the rear brakes.

In our case, I've activated the TCS system several times during driving but it's always engaged when it should (although not when I would if I were the computer!). I've found it to be remarkably sensitive, if I boot it even the slightest amount coming off a light and turning right it will usually engage - which is correct. You raised an interesting point though, don't each of the ABS/TCS systems fall under the umbrella of the Stabilty System?

Your post got me thinking about the stability system so I cracked open the service manual. Check this out;

......

However, the next paragraph might be of interest to your situation. "When braking during VSES activation the pedal pulsations feel different then the ABS pedal pulsations. The brake pedal pulsates at a higher frequency during VSES activation." Perhaps that can help you to isolate which system is active when you pull up to the lights and get the pedal pushing back at you etc.

If I were experiencing your symptoms I'd scan for codes because with the way your problems are presenting there's probably codes present. It may well be one issue causing the whole lot of the symptoms. In fact, I'm almost sure it would be.
This is all good stuff, and I commend your troubleshooting. Here is my thinking though. If any part of the TC system is activated the light comes on. Also when the TC is manually deactivated there should be no recognised input from any of teh above sensors. yaw control, or steering position. What I'm getting at if this is a sensor related problem ( and assuming the ECM doesn't catch the sensor failure). The computer should still show the TC active, assuming the manual override is not set. This being said if it is a computer related problem the error would not be in the input but the computer itself. Is my logic sound ?


I'm gonna try to draw a picture..... ok, if the problem is with any of the inputs it shoudl trigger a TC active on the display, or a sensor failure. If I'm correct you said it did not. So your getting output from the abs modulator that you, but no display information. If your also noticing engine retardation then the problem is joined thus making it a CPU problem. However if it is only noticeable in the abs modulator. It could then be the modulator itself or again a CPU problem. If i'm not mistaken each system CPU communicates with the main CPU via the serial connection line, not just a voltage regulation. in other words the ABS shoudl mistakenly be activated as it activates based on a specific code (I'm assuming here based on wiring diagrams). So I guess what I am getting at is you may want to look into weather the problem is a CPU problem.

....................................... ________________
[yaw sensor]-------------->|............................|======>[heads up display(DBII CODE)]
.......................................|.........CAR.............|
[steering pos]------------->|..........CPU............|======>[output to ECM subsystem]
......................................|............................|
[wheel pos]--------------->|________________|======>[abs modulator sub system]
 

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The ABS, TCS, and VSES are all tied together in the CTS. While they work together to keep the shiny side up, they also work individually and have their own sensors, wiring and trouble code system to aid in diagnosis. The EBCM is the brains of it all and will throw trouble codes and shut down the ABS system in the event of a failure. Normal braking will not be affected and as the OP has stated, there are no trouble codes present for any vehicle system. The amber ABS light would be on if there were a problem with the ABS; The service stability system message would flash if there was an issue there and the service traction control system message would flash if there was something wrong there. Since none of these warning messages or lights have appeared, before jumping into expensive parts replacement, check the basics for what typically causes brake drag..... Misadjusted brake pedal rod, misadjusted brake booster rod, or a malfunctioning brake booster (a hard brake pedal would result also). If all of these check out, I would start to look at the EBCM or the brake pressure modulator valve as the next possible culprits. The EBCM could either be reflashed or replaced and the BPMV would just be replaced.... BUT.... I would not throw money at them without having it properly diagnosed.... they are expensive parts and it would be a costly mistake if these are not the problems.

Briggy, I think you are fairly right on your explanation..... the EBCM receives its inputs from the TCS and Stabilitrac and then reports it to the PCM which in turn, tells the EBCM what to do depending on the situation. Since these systems are all tied together, if 1 sensor goes down in a system, the rest of the system won't work because the computer doesn't have all of the information it needs to make a decision. If I sound like I am speaking in laymen's terms, it is only because this is the way I understood it as I just read the entire ABS system description and operation on my GM service software. I am curious as to what the problem is with the OP's car but I don't want to see him throw money at parts that might not fix it.

To mmiller... if your buddy has a good scan tool that can read ABS and traction control systems and you know how to interpret the info, I would spend some time with it before buying parts. Problems like this are a bear to diagnose when you don't have any trouble codes or apparent system issues to start with.
 

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Discussion Starter #30 (Edited)
The ABS, TCS, and VSES are all tied together in the CTS. While they work together to keep the shiny side up, they also work individually and have their own sensors, wiring and trouble code system to aid in diagnosis. The EBCM is the brains of it all and will throw trouble codes and shut down the ABS system in the event of a failure. Normal braking will not be affected and as the OP has stated, there are no trouble codes present for any vehicle system. The amber ABS light would be on if there were a problem with the ABS; The service stability system message would flash if there was an issue there and the service traction control system message would flash if there was something wrong there. Since none of these warning messages or lights have appeared, before jumping into expensive parts replacement, check the basics for what typically causes brake drag..... Misadjusted brake pedal rod, misadjusted brake booster rod, or a malfunctioning brake booster (a hard brake pedal would result also). If all of these check out, I would start to look at the EBCM or the brake pressure modulator valve as the next possible culprits.
Agreed, been there done that. With respect to the booster - the power brakes work just fine. With respect to the booster rod going into the master - it's never been touched and it's so unlikely that I'm going there (we know the full history of the vehicle - it's a creampuff and none of these areas have been touched).

Just to recap (again) the calipers were checked - the slides are as loose as a goose. The 4 pistons were checked - they are as smooth as silk. The stainless brackets the pads rest on - cleaned, lubed and adjusted.

From a brake mechanical standpoint - it's really, really unlikely that a pair of calipers are going to intermittently drag at the same identical time. Same thing with the brakes hoses - that would mean both front brake hoses are intermittently failing at the same time - it's not going to happen.

The master cylinder was taken out of the equation because I was able to get the car to exhibit the drag problem and was able to quickly crack the lines at the master - the pressure at the calipers was not released.

This means that the pressure is being held lower in the brake system. What's below the master and before the brake hoses? The brake pressure modulator and the EBCM. The EBCM is not going to typically hold pressure to the front brakes unless the software program that drives it is faulty.

If it were a TCS engagement it would occur at the rear wheels - it's not. That alone takes TCS out of the equation. TCS does not apply the front brakes - it applies the driven brakes (rear wheels) and only as a last resort.

In theory, the Stability System could activate the fronts as it's designed to send differential pressure to the front brakes. However, the vehicle will exhibit the issue being driven in a straight line at normal speeds with the foot off the brakes and absolutely zero lateral load. Not only is there no reason for either TCS or VSS to be engaged - they're not. There is no information on the dash indicating engagement.Think grandma driving up a long straight hill and you'll have the right picture :)

EBCM or brake pressure modulator valve - the modulator valve is going to be replaced


The EBCM could either be reflashed or replaced and the BPMV would just be replaced.... BUT.... I would not throw money at them without having it properly diagnosed.... they are expensive parts and it would be a costly mistake if these are not the problems.
There's nothing left to diagnose :) The facts are this simple. It's not the master and it's not anything below the front brake hoses. There is only item left between the master and the hoses and that's....the brake pressure modulator.

To make it even more decisive, when I was able to get the vehicle to do it (when I got home) and removed the lines to the master the vehicle was turned off. None of these systems were powered up. What then can hold pressure to the front brakes when it's not the master and it's not anything from the brake hoses down? Only the ABS modulator can do that. It's the only thing that can still maintain pressure against the front brakes when the car is physically turned off and not moving and the master has been disconnected.

The master cylinder, being disconnected, removes the master cylinder from the equation and also everything attached to it. This includes the brake booster and the rod going from it to the master.

So, we can now take out the entire master cylinder and brake booster assembly from the equation. We can also take out anything from the front brakes hoses down. We can also take out any modules being active because the car is turned off.

What's the only item left that can maintain pressure at the front brakes under such conditions? The ABS Brake pressure modulator. It's not physically possible for any other item to do this when the master cylinder is disconnected and the car is turned off. The pressure has to be held lower in the hydraulic system and the only thing left is the ABS BPM.

This is not diagnosis by replacement. A great deal of time and thought has gone into this intermittent issue. Along the way there have been several excellent suggestions that, while being incorrect, caused me to understand the system in ways I had not thought of. However, in each case the culprit can really only be one thing at this point - the ABS Brake Pressure Modulator.

One other key point, even though none of the other systems (TCS, VSS or what have you) were active when this issue has arisen, the interesting part is that every one of these systems uses the ABS Brake Pressure Modulator as it's method of activation. It's the common component and without it none of these systems would work. I'm digressing because it really comes back to being this simple;

If we know the front brakes from the hoses down to the calipers are free and not causing the pressure to be held, and we have disconnected the master cylinder lines, and the vehicle is turned off, and the front wheels are still dragging considerably then we know, beyond any reasonable doubt, that it HAS to be the Brake Pressure Modulator that's maintaining the pressure to the front brakes. There is NOTHING else it can be.

That's not diagnosis by parts replacement, that's very precise diagnosis by any measure of any shop with a truly brilliant driveability technician. In fact, I wish I knew of a shop that would do diagnosis like this as I'd rather not have to do it ;-)

To mmiller... if your buddy has a good scan tool that can read ABS and traction control systems and you know how to interpret the info, I would spend some time with it before buying parts. Problems like this are a bear to diagnose when you don't have any trouble codes or apparent system issues to start with.
See above (in bold ;-) but I did take it down and scanned it myself. I was primarily looking at the Steering Wheel Angle Sensor because I had replaced that a few years back and, just for giggles, wanted to check it. It was reading properly.

Unfortunately it was a lower end Snap-On tool and so I could not activate any of the ABS brake functions individually. (I would have loved to activate valves in the BPM manually several times to see when it would keep the pressure to the fronts).

A specific shout-out to Flavoade - my cousin was an expert driveability tech at a GM dealership before I sold him his current shop. I mentioned your specific case to him and that I had felt that one issue could be causing your entire spectrum of problems. He agreed with me right away and picked off a wheel speed sensor as the likely culprit. He told me that they often fail at low speeds (not enough power to generate a signal) and that the vehicle will often interpret this as a traction problem because the wheel drops 'off the chart' causing all sorts of system to activate.

I felt right from the start that the whole gamut of your symptoms could be caused by one item - he strongly felt the same and picked it off right away. From your description it sounds like all these events happen at low speeds and that's exactly where he said vehicle speed sensors typically fail (or drop off). So I'd encourage you to look into that - it might well be that simple and that cheap to address all your issues in one shot.
 

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Discussion Starter #32
Will do - but I can't fix it until GM sends me the part and right now they've placed that specific unit under National Control. So it seems there's an issue on their end with that specific part number.

It's probably because they've been so poorly boxed they are getting sent back due to freight damage like the last one I ordered :-(
 

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I have a 2004 CTS that is doing the exact same thing. Please, please post your findings. I appreciate the thread. I'm hoping you find the smoking gun with this problem.
 

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Discussion Starter #34
The stinkin' part is still under national control (I called in about it this morning) so this time around I'm trying the dealer as opposed to my local AC Delco supplier. It means I pay a little more but the chances of the dealer being able to get it are much higher. I only hope they don't send out the same damaged unit they sent me last time....

With respect to posting back once it's installed, I'll be happy to if I find it's still doing it. I can't really see that happening given that I've eliminated everything above the pump and below it...

Have you checked all the obvious causes? This seems (to me at least) to be a pretty rare intermittent issue.
 

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Discussion Starter #35
Well, look what I got. It finally showed up after all this time and this one doesn't have any bent valves :2thumbs:

The nice thing is that it also comes with a new brake fluid pressure sensor as well as the pump relay. I've been wondering if the issue could actually have been caused by the brake fluid pressure sensor but there seems to be little info from GM about it.

Anyway, on to the install and the bleed :thumbsup:


 

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Well, look what I got. It finally showed up after all this time and this one doesn't have any bent valves :2thumbs:

The nice thing is that it also comes with a new brake fluid pressure sensor as well as the pump relay. I've been wondering if the issue could actually have been caused by the brake fluid pressure sensor but there seems to be little info from GM about it.

Anyway, on to the install and the bleed :thumbsup:


nice looking forward to the report back. I'm guessing this is the unit on the passenger side of the engine bay front ?
 

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Discussion Starter #37 (Edited)
Correct - here's some shots of it in the car....





Now here's the interesting part (and a confirmation that the ABS Pressure Modulator actually fixed the issue).

I bled the thing like you wouldn't believe. In fact, it was more of a flush then anything else as I ended up putting 2 liters of brake fluid through it. Of course, the master had run dry during the modulator replacement so everything was full of air.

I pressure bled it at first to get it started and then gravity bled the daylights out of it. I then test drove it and bled the master some more until brake operation and the pedal worked perfectly. Now here's the kicker....

I was basing the pedal feel on how the pedal felt prior to repair, which was high and hard. I really liked the feel of the pedal prior to repair. However, after some driving and re-bleeding I was certain I had gotten as much air out of the system as possible, yet the pedal was lower and softer.....

I went down to visit my cousin at the shop and asked him for some of the hoses/fittings used for bench bleeding the master (I was going to re-bleed it that way) but I really felt I might be chasing a ghost as the brakes do work perfectly - it's just that the pedal is not as high or firm as it used to be.

My cousin listened to me describe the bleed procedure I had done and said, literally, that I was chasing a ghost. He said the reason the pedal felt softer was because the brakes were no longer being held on and that it was a confirmation I'd cased the issue. I think he's 100% correct. If there's any air left it's going to be a very small amount...

With respect to trace amounts of air being left, he said drive it for a week, let the air migrate through the system and then crack all the bleeders at that point - if I wanted to be 100% certain there is no air left.

Originally I thought that I would not be able to confirm this issue as 'case closed' due to the intermittent nature of the problem but I think my cousin hit the nail right on the head when he said the pedal should be softer. He likened it to a car with sticky calipers where the pedal is always high and hard and when the calipers are replaced it tends to be lower/softer because the calipers are now free to move.

My conclusion: Case closed. Realistically, we had taken everything out of the equation except for the possibility of a software error on the part of GM (had the pressure modulator not addressed it). Given that the pedal feel and height has changed considerably leads me to believe it's a tactile/tangible sign that the issue has indeed been addressed. In a weeks time I will crack all the bleeders but I already know what I'm going to find - nothing more then the peace of mind that comes from knowing that all the air has indeed been removed from the system :)

So there you have it. Just to recap this thread in one post;

The original issue was that both front brakes were intermittently being applied at the same time during normal driving conditions
The vehicle had no codes whatsoever
The caliper pistons were checked to ensure they weren't seized/seizing - they were free
The caliper slides were checked to ensure they were free - they were
Given that this occurred intermittently to BOTH front brakes at the same time brake hose failures were immediately ruled out
The master cylinder (and the booster and adjustment rod) were ruled out because I was able to get the vehicle to exhibit the problem in the car port and removing the lines to the master cylinder did not free up either wheel (therefore, the pressure must be applied from lower in the system)
Lastly, given that we know that the pressure is not being held to the front brakes from the brake hoses down, and, given that the master cylinder and everything above it is not holding the brakes on, the only component left is the brake pressure modulator.
And finally, concerns were raised that the brakes could be held on by one of the on-board management systems however this was taken off the table by two facts - one, none of those systems were engaged when the vehicle exhibited the problem, and two, when the vehicle exhibited the problem in the car port the ignition was turned off and yet the front brakes remained on. (those systems were not powered up).

So, if anyone encounters the same issue - that's a quasi-troubleshooting flowchart you can follow. Either way, we now know for a fact that the brake pressure modulator can actually cause these issues to occur.
 

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Discussion Starter #38
Just as an aside, I was looking through the threads and found one mentioning an on-line VIN decoder. I tried it out and this is what it reported;

"There are 20 2003 CTS 4 DR vehicles (0.027%) matching your exact options list. There are 23 (0.030%) with at least as many options."

Cool !
 

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Good work... If your cousin has a Tech 2 or other scanner that can bump the ABS system while you bleed the brakes, this will help get rid of whatever air that may be left in the system and should stiffen the pedal some more.
 

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Discussion Starter #40
Yeah, no dice on that (I checked). All he has is the standard Snap-On unit and it didn't have the routine for brake bleeding :-(

I did think of the underlying concept though so what I did was during the first test drive I nailed the brakes and activated the ABS and the traction control in an effort to cycle the pistons and purge the modulator. After that I bled the brakes several more times (and the master as well). At that point I did get more out of it and a higher/firmer pedal.

I'm pretty sure there's nothing left in it but I think his advice about checking it in a week is a good idea if for no other reason then knowing 100% that it's clear. I'm just happy that it didn't end up being a really weird issue - the kind that can't be repaired at the shop level (something like a software design issue or the like). I get concerned with things like that because I've run into them in the computer industry where the only way to resolve an issue was to get an engineer to write a custom firmware. The tough part is not identifying the problem (or even the solution) - it's getting in touch with the person who can and at that point it always seems to boil down to how many people are impacted by the issue etc. Usually when you're the first you don't get too far :)
 
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