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2012 CTS coupe RWD (Service Power Steering) - Assistance needed

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cadillac coupe cts power steering rwd
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25K views 105 replies 12 participants last post by  Padgett  
D
#1 ·
Hey everyone!

My 2012 Cadillac CTS Coupe RWD has been having major power steering issues lately. The fan that prevents the vehicle from overheating went out along with the overheating fan at the same time. I had the fan replaced. Now the vehicle is no longer overheating but the "Service Power Steering" message still comes off and on while I am driving. When it does come on, it is hard to steer. It is not on the entire drive but it is fairly frequent. Any ideas as to what could be wrong? I bought a new power steering pump and am going to have a mechanic put it in but he told me it could be other things as well and I do not want to waste the money if that is not the cause as it does go in and out. I was also told it could be the oil center unit needing replacement because it is not transferring fluid to the power steering. Any ideas as to what this could be or how I could figure out the cause for sure prior to paying for a costly job? Perhaps others have had this issue and can advise how they fixed it?

Also note that my power steering fluid is full.

I would appreciate any assistance you can provide. Thank you!
 
J
#2 ·
The most common cause of loss of CTS power steering, particularly in an intermittent fashion from what I have observed here, and experienced personally is a bad alternator. Pull up the voltage on the display and observe it when the problem is present. If voltage is below 13 volts during the episode for an extended period of time the charging system needs to be checked by a capable service facility (Some unfamiliar with modern charging systems may condemn a good alternator in error). With headlights on, voltage should always be over 14 volts and specifically ~ 14.6v. When the motor is running, voltage should always be above 13v with engine running although the computer has the ability to command it much lower.

Also clarify if the problem was present before, or after the fan failure.
 
D
#3 ·
On 14V when I started it but quickly goes in between 13V-13.5V up and down idling. Went to 14.6V and then back down to 12.5V idling.

Turned off and back on in garage. Idling at 12.4V when I started it.

13.1V-14.4 max when driving. 14.4V going 40MPH. Seems to fluctuate with how fast I am driving. It did go to 14.8V after driving for a while but eventually changed.

Seems to fluctuate a lot if I turn vehicle off/back on.

I was unable to reproduce the power steering message/problem on this drive (first time it did not happen quickly). However, I turned it off and back on and the message came on right away with the hard to turn steering. I backed out of the garage and drove. It stayed on 14.2V while driving with the problem occurring. Please keep in mind it did not come on when I was driving this time, not sure that matters.

My vehicle sounds like it is gargling every 15-20 seconds when idling. Not a normal idle. You can hear the fan kick on after a while.

The radiator fan failure went out first then the service power steering message came on.

When I was able to reproduce the message/problem just now, after seeing the voltage I turned the vehicle off and back on once again. The message was now gone, and I was able to drive without that problem.



Do you still think it is my alternator needing replacement or something else? Any advice is greatly appreciated.
 
J
#6 · (Edited)
It's too early to tell/guess at, at this point without some form of component testing, despite the voltage range you observed being all over the place for a 2012 in my opinion, that has the newer computer for engine management relative to the 2008-2011. Although the computer commands the output voltage of the alternator, voltage below 13v, is insufficient for the vehicle as a whole except for a brief moment

. I observed nearly exactly what you described for about a year with the alternator values (but no steering issues), where the display showed a range mostly in the mid to high 13v range, and over 14 volts with the headlights on. According to GM, the system should deliver right at 14.6v with the headlights turned on, so that is often used as a performance marker in situations like this where there is suspicion of a charging system problem. The default output setting is 13.6 volts, should the alternator be powered, without a pulse width modulation signal (like in the case of a modern alternator swapped into an older car without proper computer control).

My suspicion from the start, was that your charging system was probably experiencing a wide voltage swing, dropping low enough to trigger the power steering problem. The CTS has a low speed power assist, unlike most other domestic cars, where power steering is present as long as the parts are good and the motor is running. Strangely enough, instead of the check charging system warning in the event of an alternator problem, the check power steering warning usually crops up first, with loss of assist.

It happened to me about two months ago. The car was fine at initial startup and drive. I parked for about 35 min and immediately upon restart the power steering warning came on and there was little if any power assist. I immediately checked the voltage reading and it was flat lined in the 12 volt range as I expected, given a few weeks earlier, the voltage output stuck in that range while I was driving and didn't move until I shut the car off at a stop light and restarted it. If I had not done that, I probably would have encountered the power steering problem shortly afterwards. I had been watching it off and on for quite a while, before the alternator finally quit. In hind sight, I should have replaced it at the first sign, as I realized after the fact that had it happened to my wife she would not have been able to steer the car without considerable exertion.

You should also have the car scanned for computer and body control module (BCM) codes as BCM codes are not represented by a warning light. Have the charging system checked, some places like the most common neighborhood part stores will do it free of charge, but if they do not plug anything into the diagnostic port, chances are they are not able to test it thoroughly, by commanding specific voltage output.

A key take away from my experience, is that once my alternator was replaced, the voltage almost always sat around 14.3 volts, or higher. Initially I thought something was wrong, because the old alternator never did that, it hoovered mostly in the high 13.8 volt range, going over 14 volts when the headlights were on.

Investigate the gurgling noise if it was not present before, to make sure you do not have air in the coolant system. If the air conditioning compressor is cycling on and off, you may notice a slight stumble in engine idle from time to time. ~15 sec intervals gives me the impression it's on and cycling.

Don't throw parts at the car, I wouldn't put that steering pump on without a confirmed failure, especially given most bad power steering pumps whine. Understand that the computer has the ability to command the voltage output over a wide range, but there is a minimum effective range necessary to support the vehicle requirements and be able to charge the battery at the same time and that tends to be at, or above 14 volts more so than below that. You can find documentation on the web, by searching GM alternator duty cycle and clicking images at the top of the browser to see pictures of it.

Also keep an eye on your battery voltage at power on before the car is started, particular the first start of the day after sitting for a day, or two. If you're seeing frequent voltage in the mid to low 11 volt range, you may be due for a battery replacement also.
 
#12 ·
Charging System Test
Charging System Test
Diagnostic Instructions
Reference Information
Description and Operation

Charging System Description and Operation

Electrical Information Reference

Testing for Intermittent Conditions and Poor Connections

Circuit/System Testing
  1. Ignition ON, verify that no G13 generator or B18 battery current sensor DTCs are set that would cause a charging system concern.
  2. Ignition OFF, measure the voltage across the battery terminals. The voltage should read 12.0 V or greater at room temperature.

  3. NOTE
    Note
    Ensure vehicle accessories are OFF for the next step.

    Engine ON, increase engine speed to 2,500 RPM. Verify the battery voltage is between 12.6−15.0 V.
    • If not within specified range, replace the G13 generator.
  4. Engine ON, increase engine speed to 2,500 RPM. Turn ON all vehicle accessories. Verify the battery voltage is between 12.6–15.0 V.
    • If not within specified range, replace the G13 generator.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Generator Replacement (LFX) | Generator Replacement (LSA)
 
#14 ·
Padgett said:
Sorry but I like the BT-360 (and many clones) better. These do an extensive array of tests of both batteries and charging systems. Easy way to tell this kind of tester is plastic terminal clips each with a separate wire to each side of the clip.
An all metal clip cannot do the same tests.
View attachment 592772
Click to expand...
No worries, Padgett.
I respect your decision and years of knowledge and experience. However, I have compared my results with commercial grade equipment and the readouts are nearly identical.
 
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D
#16 ·
Just wanted to update here. Took it to OReilly. They said I have a bad battery. However, the guy said he was not able to check my alternator since my battery is bad. Not sure if that is true or not. Vehicle is still running fine but the intermittent power steering issue is still occurring. This leads me to think it is either the battery or the alternator or the charging system. I am thinking of taking it to Chevy for diagnostics then somewhere else to have it fixed for cheaper. Anyone have a better idea or know if I was given the wrong information?
 
J
#18 ·
My dying alternator would have passed all of the testing milestones in the diagnostics posted above before it quit altogether. 12.6v with everything "burning" and no time constraint is vague GM. I'm not sure about the LFX, but I imagine the alternator removal is about the same, pretty easy as alt changes go, just be sure to disconnect the neg battery cable first. I would look into having it rebuilt as a shot in the dark before doing the dealer dance if I were you, provided it has more than a 100k miles on it. If it did not resolve the problem the expense amounts to preventive maintenance.

If I had the problem, I'd sit down and look at the wiring diagram to the assist solenoid and tap into it without altering the harness itself, or just replace the solenoid and test, given solenoids frequently have intermittent failed conditions where some times they work and some times they don't. I believe there is a high probability that the alternator and solenoid are at the proverbial fork in the road. I'm not suggesting ebay as a source, but it was the next best thing since the part didn't popup on rockauto.

www.ebay.com

Cadillac GM OEM 08-15 CTS Steering Gear-Solenoid 25830755 | eBay

Find many great new & used options and get the best deals for Cadillac GM OEM 08-15 CTS Steering Gear-Solenoid 25830755 at the best online prices at eBay! Free shipping for many products!
www.ebay.com

They have it, but it has to be searched for using the part#;

GM GENUINE 25830755 Power Steering Pressure Sensor | Shop Now at RockAuto

GM GENUINE Steering Parts and More for Your Vehicle at Reliably Low Prices. Fast Online Catalog. DIY-Easy. Your Choice of Quality. Full Manufacturer Warranty.
www.rockauto.com
 
#19 ·
if you decide you need to take it to a dealer...find out up front if the diagnostic fee is rolled into the repair should you decide to have the repair done at that dealership while they already have hands on your vehicle...

what is the voltage read out in the Driver Information Center (DIC) with the ignition on but the car not running???...try this after the car has been sitting and not right after a drive...

depending on the age of your current battery you should get one and get a good one...that could alleviate your issues right there but hopefully you get your answers without out putting too much cash...

good luck with your car...

Bill
 
J
#20 ·
Yes, "arm" yourself before going to the dealer. The info shared here about the basic system characteristics can help you ask the right questions about what you're paying for. Since that solenoid is a pressure switch, I'd imagine the pressure can be tapped into and followed to determine the status when the event occurs when the proper diagnostic tool is being used.
 
J
#22 ·
Good example on what to expect from a bad pump presentation;

www.cadillacforums.com

Power Steering Issue

I searched but did not find much; my 2008 V8 SRX has almost no power steering assist when turning at low speed or parking. If I put it in park on the driveway and turn the wheel it is very difficult. If I rev the engine, the steering feels normal but there is a whining noise like you would...
www.cadillacforums.com www.cadillacforums.com
 
D
#23 ·
UPDATE:
I heard whining so I figured power steering pump. Had it replaced since I already had purchased it and it did not fix the issue.

Took it to AutoZone and OReilly to test battery/alternator - They both said my alternator was the culprit because it was only putting out 12.5V. They also said it was only charging my battery 45% but the battery wasnt "bad" per say. Just was not being charged. I will take it to a certified mechanic this week to confirm diagnosis and have the alternator replaced if that is the case.
 
#26 ·
This ^^^
These cars don't seem to like the parts store junk.
New OEM or rebuild yours by a local shop that specializes in rebuilding alternators.
 
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#33 ·
CSIMME01 said:
12.6 volts is not indicative of a bad alternator.
Click to expand...
The lowest I have seen with a good alternator is about 12.8V, but your point about voltage that would be considered "low" for a dumb alternator not indicating a bad alternator on the CTS computer-controlled charging system is correct.

From my experience so far, the best indication is spending a lot of time in the high 13V range, rarely reaching 14.4V, and never reaching 14.9V or 15.0V, at least for an appreciable length of time.

One can hook up the Tech2 and monitor current going into the battery for a more definitive check.
 
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D
#36 ·
I was quoted close to $500. However, the new mechanic ran codes and came back with CO450-0B. He wants to replace the Solenoid. The Cadillac manager told me he has seen this many times. He stated although I get that code, it’s more than likely the alternator. Not sure what to do at this point.
 
#37 ·
Fix the alternator via rebuild or OEM replacement, this is a common problem. Obviously rebuild is less expensive and a good approach, your mechanic is probably planning on this given the $500 price tag. I did this myself for $130 (R&R the alternator, had a local shop rebuild it), but not everybody is able to DIY. Whatever you do, don't let him put in a Chinese alternator!
 
#47 ·
My thoughts are
1) it's your car to repair however you want
2) a repair that doesn't fail and strand or inconvenience is worth more than any warranty
3) cheaply-manufactured or poorly-rebuilt alternators are famous for early death
 
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#56 ·
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J
#61 ·
I considered rebuilding mine with OE parts, but upon discovering the regulator and diodes alone arrived at somewhere between $80-100 together and I'd still need OE quality bearings and brushes, a low mileage used original part ~$35 was far more practical for me and already proven reliable. It made me question the local rebuild quote of about $135. If I can't get the new parts for less than that, exactly what kind of parts are they using and what's being replaced if they can turn a reasonable profit at that price point.
 
#71 · (Edited)
The alternator shops are paying wholesale prices for parts, in quantity. Neither bearings, brushes nor the internal electronics are particularly expensive.

If GM can sell you a brand new alternator with aluminum case, copper-wound stator and iron rotor at a profit for $250, you can be sure the cost of the electronics isn't $80. It's the same story as always, they'll try to squeeze you for every $$ they think they can.
 
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#62 ·
Does the car start and drive normally? Have you had to jump start the vehicle or had a no start because of a dead battery? If the answer is no to the above questions I have a hard time believing the alternator is bad. I also don't see how a bad alternator would create a high current code in the steering solenoid. Low voltage would create lower current, not higher.
If the alternator was overcharging and creating high voltage it would set its own code.
Just my opinion.
 
J
#63 ·
CSIMME01 said:
Does the car start and drive normally? Have you had to jump start the vehicle or had a no start because of a dead battery? If the answer is no to the above questions I have a hard time believing the alternator is bad. I also don't see how a bad alternator would create a high current code in the steering solenoid. Low voltage would create lower current, not higher.
If the alternator was overcharging and creating high voltage it would set its own code.
Just my opinion.
Click to expand...
Joined a little over 12 mo ago, you're new to the game. Most who have been here for a while are aware that more often than not, the first sign of an alternator failure is loss of low speed power assist, as was the case with my experience about 2 mo ago. No dead battery, or sluggish starts, just an immediate check power steering warning at startup, followed by my immediately checking the voltage reading on the dash, which delivered what I expected to see, a 12 volt range reading with headlights and heat on and radio bumping. The check battery warning didn't come on until after I drove 2 miles, turned the car off and back on. It can always be something else, but the most common should be addressed first.

It's possible the steering assist goes out as a result of programming for energy saving mode to buy time, or an oversight in programming that leads to it. For example, when the motor starts to overheat, the A/C is disabled to prevent making matters worse. The current error may be referencing what the PCM is having to command in order to achieve the desired result. There is an amp probe on the negative cable so it can detect how much of the load is being carried by the battery, which would be substantially increased in an alternator failure.
 
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