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Sporadic SES light and exotic codes - friend's 2004 DTS

27K views 184 replies 10 participants last post by  Ranger 
#1 · (Edited)
Here I was thinking my Cadillac troubles are over but ... A friend owns a '04 Deville DTS and was complaining to me about the SES light coming on and off randomly. He asked me to have a look since I went through so much trouble with my old Seville. During a test drive I didn't notice anything strange but a rough idle with slightly elevated rpm that totally goes away the warmer the engine got. The Deville also has abyssal gas mileage of below 13 MPG. After a couple of miles the SES light indeed came on and stayed on until we parked the car. 10 minutes later we got back in the car and drove the same route back with the light not coming on at any point in time.

Strangely, it is not throwing any code that can be read out with the internal code reader but two codes concerning the front seat adjustment motor. One remains of my old Seville was an external code reader that threw out the following:

Trouble Code: P0174
ABSLT TPS(%): 14.5
ENG SPEED(RPM): 2027
CALC LOAD(%): 50.2
MAF(gr/S): 29.45
MAP(KPa): 71.0
COOLANT(°C): 94
IAT(°C): 27
IGN ADV(°): 39.0
SECOND AIR: ATMOS
ST FTRM1(%): 8.6
ST FTRM2(%): 0.0
LT FTRM1(%): 21.1
LT FTRM2(%): 24.2
VEH SPEED(KPH): 78
FUEL SYS 1: CLSD
FUEL SYS 2: CLSD

After some quick research through this board, it could be a vacuum issue. We did a quick check of all apparent vacuum lines and the only one showing clear signs of degradation is the one circled yellow in the picture below. The rubber hose part is cracked by an inch (on the bottom) and the hole connection is very shaky and loose.

Auto part Fuel line Automotive fuel system Engine Vehicle


Unfortunately, I have no idea what that particular part is or what it's supposed to do - and therefore does not know whether this could be a/the cause for the SES light. I also read here on the boards that I should just get a can with some carb cleaner or so, carefully spray the vacuum lines, and listen for rpm changes to isolate any vacuum leaks. I'd like t do that but was unable to find a picture or diagram clearly marking all candidate spots. Is such a treasure hidden deeply somewhere?

EDIT: I didn't notice this at first with the code reader: P0174 is marked as "pending" while P0171 was "confirmed". Don't know how that translates into the H/C marks with the in-dash reader.
 
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#33 ·
Re: P0174 on a 04 Deville

Yes, I think I have done my research and found a tool called "brake cube" at Harbor Freight for $4. I have also updated my torque wrenches to providing much higher setting for the 100 ft/lbs for properly attaching the wheels. One concerns remains though: he had a leaking master cylinder and it was replaced. We have bought OE brake fluid according to DOT-3 specifications from ACDelco but I am slightly concerned about DOT-3 being deprecated. Is there a safe way to determine whether the shop switching the master cylinder had used DOT-3 or its successor?
 
#37 ·
Re: sporadic SES light and exotic codes

I'm pretty sure that there is only one CC cable and I only see one in that picture.
Little update: After 5 minutes intensive search, I found the cable bundle and a broken connector under the air filter housing. CC codes went right away. Unfortunately, I had much less luck with the brakes. After disassembling just the RL, I realised that the ACDelco 14D792CH Advantage Rear Ceramic Disc Brake Pad Set does not fit a DTS. Strange, as those have been advertised for code JL9 and shown as exact fit.

Anyway, the old pads still have some life on them and the car is braking so much better now. Makes one wonder how much difference a good cleaning and proper lubrication of the caliper slide pins can make.
 
#39 · (Edited)
Re: sporadic SES light and exotic codes

Update:

1. The CC is working again after simply re-attaching the cable/wire bundle.

2. We addressed the rear brakes, changed all pads and rotors. IMHO the mechanic overstated the wear on the brakes quite a bit, since rotors and pads have had half their life on it. Anyway, the new pads produce significantly less dust, so that is a plus. However, after putting all back together and rotating the wheels at the same time, we were puzzled on how we check the proper performance of the replaced parts. The car brakes just as it did before - like a tank :eek: Compared to the braking capabilities of my Audi, I sometimes get panic attacks. Anyway, I guess the 1.2 tons weight difference do contribute to that feeling. We thought using the parking break would be a good test, it keeps the car in place on a hill but the car starts turtles away when put in drive. I personally would think that's not too much of an issue since my wifes beetle (manual) had many episodes of her forgetting the parking brake until a "funny smell" happened.

Is there any way to check that apart from bringing it to a mechanic?

3. The sporadic SES light is back. He was able to isolate them occurring at prolonged highway speed cruising. I took the car for a trip to the country I was planning anyway and, voila, probably 30 minutes into the trip at 75 mph and very smooth cruising SES came on. I stopped to see two old "friends" saying hello:

P0171 H - System too Lean (Bank 1)
P0174 H - System too Lean (Bank 2)

Funny thing is, at longer drives, the SES light goes OFF as well. The car was on a drive to Galveston with the light on at first and arrived there with SES off. :banghead: I get another bottle of spray and check the plenum area again just in case I have overlooked something at the first time. I am, maybe wrongly, very hesitant to change the plenum (because of the intake gaskets and everything) if this is not the major reason (The earlier repair with the PCV hose did wonders so far, even the MPG's jumped from below 13 to 18).

EDIT: It took so long because Amazon send me the wrong pads - I took one old pad and walked into an Advanced to find out the correct part number. i was lucky, a customer returned compatible pads but did not put the springs back in the pack. Got a set of 4 Wearever Ceramic pads for $15 and just recycled (cleaned and made sure they were "springy" enough) the installed springs. The ACDelco Advantage rotors fit perfectly.
 
#40 ·
Re: sporadic SES light and exotic codes

We thought using the parking break would be a good test, it keeps the car in place on a hill but the car starts turtles away when put in drive.
Sounds a little like a dragging brake.


Is there any way to check that apart from bringing it to a mechanic?
The wheel should be very hot after a short drive.

I get another bottle of spray and check the plenum area again just in case I have overlooked something at the first time.
Based on those 2 codes, I still suspect the plenum duct. This time flex it as you spray.
 
#41 ·
Re: sporadic SES light and exotic codes

Sounds a little like a dragging brake.
Soory, English is not my first language. Just to avoid any misunderstanding: What I meant to say was simply that after I put the Deville in Drive, it starts going.



The wheel should be very hot after a short drive.
Will check that at the next opportunity.

Based on those 2 codes, I still suspect the plenum duct. This time flex it as you spray.
Thanks for the hint! Can the plenum be changed without taking the intake manifold (?) off (and the whole resealing)?
 
#43 ·
Re: sporadic SES light and exotic codes

I've had an opportunity to check the wheel temperature: after a normal drive the wheels are quite cool, after 40m stop-and-go the wheels are warm but nothing resembling "very hot". We'll check the plenum area with some aerosol today.

I have two more questions, though:

1. When the caddy is stopped or going quite slow a subsequent acceleration is a gurgling/sucking liquid displacement sound coming from the engine compartment. What is that?
2. The transmission fluid condition display is now down to 50%. Is this something he's to worry about?

Thanks.
 
#44 ·
Re: sporadic SES light and exotic codes

A gurgling sound is usually air in the cooling system. I'd pin point where it is coming from and check the purge line. You might be hearing it in the heater core.

Trans fluid life monitor almost always stays at 99 - 100%. The only thing that decrements it is overheating the trans. I'd change the trans fluid.
 
#45 ·
Re: sporadic SES light and exotic codes

Trans fluid life monitor almost always stays at 99 - 100%. The only thing that decrements it is overheating the trans. I'd change the trans fluid.
I have not had the time to check the plenum yet but I was discussing (and researching) the transmission fluid change. Here on the board there seems to be an opinion that it needs to be done personally to make sure it's done right and that the mechanic is not damaging the systems by force flushing it. So I guess one of those $49.99 trasmission fluid changes is out of the question?

If I may trouble you with another question: the Deville's computer sees to suffer from amnesia since a couple of days. I got a call three days ago that the MPG display reset itself to 0.0 for no apparent reason. It continues to do so several times a day right after the car is started. Battery power is ok and all other systems work perfectly. Is this and indicator for yet another big(-er) issue?
 
#46 ·
Re: sporadic SES light and exotic codes

If you go in for a $49.99 special ask specifically what they are going to do and how they are going to do it. Personally I want the pan dropped and cleaned out along with the magnet. A fluid exchange by a machine is the easy way of changing the fluid and does not accomplish that. In fact, depending on the pressure involved, it might just stir up any debris in the pan. If the word "reverse flush" is mentioned, run like a pair of cheap pantyhose.

Not sure what to say about the MPG display.
 
#47 ·
Re: sporadic SES light and exotic codes

I have done some routine maintenance yesterday and while the car was jacked up anyway, I checked the parts of my friends car. Just as with my old Caddy, the problems never stop:

  1. The rear shocks are leaking massively. After telling my friend a rough guesstimate about the DTS shocks he almost fainted. We have a pick&pull with a huge Deville stock about 15m away, would it be possible, advisable or whatever to just bridge the remaining years of the car. It has 135k miles already and spending another $2k on just the rear shocks is steep.
  2. I located and fixed another vacuum leak. However, the car is shaking a lot just after start up with a cold engine. It goes away after two minutes. There is also a noticeable loss of power during this time. The engine is purring afterwards and runs strong.
  3. Does the Deville DTS has some kind of rpm delimiter? When in N, the needle goes to ~4200 and jumps back to 3500. This is also the point in which a slight hesitation appears when in D and just push the pedal to the metal.

Next thing on the list is the transmission fluid change.
 
#48 ·
Re: P0174 on a 04 Deville

The engine has an rpm limiter at about 4,000 in P or N - to keep you (us) from trying to over-rev an unloaded engine.

Engine miss for 30 - 45 seconds after cold start is NOT GOOD. That's one of the telltale signs of failing head gaskets: The engine cools, a tad of coolant leaks into a cylinder(s). You start the car, the coolant shorts the plug electrodes to ground for some number of revolutions - the coolant blows out the exhaust port(s) and the engine smooths out.

Used rear height control shocks are a crap shoot - but cheaper than the new article. Your (his ?) call.
 
#49 ·
Re: P0174 on a 04 Deville

The engine has an rpm limiter at about 4,000 in P or N - to keep you (us) from trying to over-rev an unloaded engine.

Engine miss for 30 - 45 seconds after cold start is NOT GOOD. That's one of the telltale signs of failing head gaskets: The engine cools, a tad of coolant leaks into a cylinder(s). You start the car, the coolant shorts the plug electrodes to ground for some number of revolutions - the coolant blows out the exhaust port(s) and the engine smooths out.

Used rear height control shocks are a crap shoot - but cheaper than the new article. Your (his ?) call.
Argh, Sub - I thought this HG business was resolved in the 2004 model year :-( That would be bad news to carry.
 
#53 ·
Phew I hope not. The owner is a big Cadillac fan but with even less knowledge about working on a car than me. After I fixed the one vacuum leak (plenum still pending) and changed the air filter, oil filter, and oil yesterday, I took it for a spin. On the positive side, the MPG went up to 17. Anyway, I also snapped a video of a cold start. I was hoping for a better sound quality but I still have hopes one of your guys may have magic ears and hear something: http://youtu.be/N9OBVyOaRME
 
#55 ·
Thanks for the reply ranger - it is a mystery for me, the engine sounds a little rough, my OBD reader is not uncomplaining, no codes are accessible by the in-dash but the car is shaking (the camera was fixed, all shaking comes from the car). The temp gauge is indeed quick, I always accounted hat to the ambient temperature >85F and a very sunny parking spot. He had a mechanic do some repairs in January because of leaking coolant and something in the lines of a coolant crossover was replaced (as well as the master cylinder).
 
#56 ·
Re: P0174 on a 04 Deville

That C tick is 90 degrees or so, ambient 85 - 1 minute 30 seconds - I see the same rise by the time I get 400 yards up the road .............. but not when ambient temp is 45 degrees outside .....................

FWIW, On a nice, sunny day in June here, ambient 93 degrees, I have seen the temp "gauge" needle start at one needle width above the C tick before starting the engine from "cold".
 
#58 ·
c-d, reading through this I noted the car was driven to Galveston. Where is SAT/BER? Or where is the car's home? Galveston is close enough to my part of the country to ask just in case the next point is not understood. My only guess is San Antonio Texas for the first and no guess for BER. In any case if you are unable to solve this I can in a hour or less.

As for the car, you have a problem that effects the air to fuel ratio calculated by the fuel injection computer (PCM). It is most apparent at cold starts because the fuel injection is still in "Open Loop" whereas the Oxygen Sensors are not yet hot enough to provide Air/Fuel ratio feed-back to the PCM for correction. This is why you are seeing repeat lean codes and have rough running on a cold start that clears up as soon as the O2 sensors start reporting the problem to the PCM. It could be mechanical such as a vacuum leak anywhere in the intake system. It could also be electrical, as the Mass Air-flow Sensor (MAF) and the Manifold Absolute Pressure (MAP) sensor may be damaged or dirty causing it to report an incorrect signal to the PCM. If one of those two signals is substantially askew it would explain all the problems also. The reduced mileage and lack of power goes with these possibility's. You have no symptoms of a blown head gasket at this time.

First test is this. With the engine cold again, before you start it, unplug the MAF sensor. This it the sensor on top of the air cleaner with the accordion tube going to the throttle body. Then start the engine and note if the engine runs worse or better. The check engine light will be on as long as it is being tested this way and will stay on with codes for the MAF signal low until you reset it. But in the meantime if it runs worse replace the MAP sensor on top of the coolant bridge. Second test, if it runs fine or better start driving it like that and note if it runs better under load where you say it's laying down now (pedal to metal in Drive). If it seems better try cleaning the MAF sensor as described in countless prior threads. If after cleaning and reconnecting the plug to the MAF it reverts to poor operation have the intake system smoke checked by a pro with the correct machine for doing this. If no vacuum leaks are found the MAF will have to be replaced as it is likely the problem. Sometimes the sensors loose their calibration but not far enough to set a code. You have one of these problems at least.

As to the problem with Uxxxx codes, these are communication codes. These along with resetting monitors at start-up point to a bad ground connection. Most often it's the big cable ground connecting the alternator housing to the RH front frame rail. Grab ahold of it and give it a tug. If it breaks or stretches that's the problem. If not clean and retighten the bolt's on each end. Check the three ground leads on the front of the transmission. They are down on the LH front of the case below the air cleaner and water pump next to the ABS pump and valve block. They each have a bolt clamping them onto the transmission. Clean and tighten all three connections. In fact it would be wise to sort the bad ground problem out before starting on the Air/Fuel ratio issue as the bad ground could easily be causing the sensors to be out of calibration.

Salvage parts from the local pick & pull yard are acceptable in all the instances above provided they look in better shape than the originals. Be sure to clean any sensors with electronic cleaner before use.

If the fluid monitor is reporting the transmission fluid is 50% depleted multiply the current mileage by 2 and you'll have the approximate point that the fluid has to be changed. Before then it's just a preventative measure.

Vernon
 
#61 ·
Manic, thank you very much about this very elaborated post - I'll follow it to the letter. Do you have a shop by any chance? My trusted mechanic back here hates to work on Cadillac (he yelled at me when I brought another Caddi in his shop and told my friend to by a Town Car or Toyota/Honda/Subaru). With my old Seville I have been to more than 10 mechanics with a varying degree of bad results. The dealerships are horrible, one of the two quoted me $7k for a 99 Seville (not a H/G issue).

On a side note: Ranger cracked it, it is indeed Berlin (that accounts for the funny English) and San Antonio.
 
#62 ·
Ah Berlin, I should have guessed, your syntax has a foreign "accent" at times, and you're willing to own VAG cars. At my shop we chastise customers who buy those but Cadillac's are welcome now that I've become thoroughly familiar with the Northstar powertrain. We do work on German cars and I actually own a BMW but the VAG's are some of the most difficult to become accustomed too and obtain parts. But I'm one of those guys who's pretty good at anything I do. As far as a shop right now I'm working at a place at the Eastern edge of Magnolia postal routes, a small town about 2.5-3 hours drive from SAT, closer to The Woodlands where the PGA course is. My oldest son and I are actively working on opening our own garage soon in Montgomery about 2.0-2.5 hours from you. That's a little far but who knows, it may be worth it if that's the kind of service you're getting at home. Ranger that part of Texas was largely settled by German immigrants back in the early day's of Texas history. The town Bourne is actually pronounced (BURN-nee) so you were pretty close with BER.

Vernon
 
#63 ·
Indeed, the drive would be a small price to pay for service - count me in for my next big service and tune-up. Regarding VAG, I am in the comfortable position that I can yell at the trainees from VW at their placement in the US in their natural language. After my second call they want me to go away and send the parts or information I need.
 
#64 ·
With the MAF unplugged, the Caddi has big trouble to stay on. The first two tried made it die after a second or two. Third try had it running but extremely rough, its idle being all over the place. Will try the MAP tomorrow (was unable to explain where to find it over the phone).
 
#65 ·
It's best to not unplug the MAF with the engine running, it doesn't hurt anything but it most likely will die. Unplug the MAF with the key off then start it up. The computer sees it as a missing signal and goes by the other sensors to calculate the load, when you unplug it running it throws everything for a loop. Be sure it's warmed up also so that the O2 sensors are working. If it runs bad without the MAF I would suspect the MAP. Try cleaning it out with a flush of intake/throttle spray before condemnation. Even with a vacuum leak the MAP,ECT, and O2's should allow it to idle and run satisfactory without a MAF signal. If not the MAP is most suspect as the others will set codes a lot easier than a bad or clogged MAP. MAP is pressure in the intake so it doesn't matter where the air is getting in. A large vacuum leak with a good MAF will cause problems because the MAF overrules the others and can't account for unmetered air getting in from someplace else. So erratic operation without a MAF on start-up is particularly damming to the MAP.

Vernon

----------

A guy brought a Subaru Impreza Wagon, 2.0 Turbo in yesterday. Said CEL on. No cel or history all monitors ready. So I drive it and notice it idles fine but strains under heavy throttle with boost etc. Scan tool shows pegged out fuel trims whenever I'm on the throttle good (+23.x %). After a few miles I decide it's definitely leaning out and not an ignition or exhaust problem. So I decide to go back to the shop and hook up a fuel pressure gauge but I unplug the MAF where I turned around. Problem solved, without the MAF supplying incorrect information the little wagon hauls xxx again. My apprentice put a new MAF on it today and cleared the code, car is ready to roll. The PCM was more than able to calculate load with the MAP and others sans the MAF, the engine ran perfect from idle to 2 BAR without the MAF. Fuel trims were back at zero by the time I got back to the shop, about 3 miles.

Vernon
 
#66 ·
Manic, I did not make myself quite clear: the car was off when he unplugged the MAF. The first attempt to start succeeded but the car died within two seconds. The second attempt, too. After the third try, the car ran but with very rough idle. We followed your procedure to the letter, however, I have difficulties implementing it: in your first post I understood that the car needs to be cold when I undergo the procedure. In the second one the O2 sensors are supposed to be warm. I'll try having him re-set the whole thing today with snapping a video.

PS: On Friday, I have the time to go investigate myself. However, the only opportunity I have to get the engine cold is at his place. The temperature down here is around 90 daytime and the engine is at full operating temperature in under two minutes. I would like to check for vacuum leaks in the plenum area again but this is quite challenging since he is literally parked under very old trees next to a country club in an area that banned any open flames. I'd suspect that playing around with a can of carb or brake cleaner on a hot engine will not come across too well. Can I substitute any flammable aerosol with a water spray bottle producing a very fine mist?
 
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