97 C5 Traction Control Problem / Reduced Engine Power in DIC

[FergieKC]

My Traction Control System fails intermittantly and causes the car to go into "Reduced Engine Power" at some very undesirable times.
It can be quite dangerous to be on a crowded freeway & suddenly be restricted to about 25 MPH without warning.

Chevy Dealers claim there is no recall ... there should be .. someone could be killed trying to find the freeway shoulder.

After shuting the engine off & waiting about 15 seconds, the reduced power issue goes away. Check Engine light stays on for 3 key cycles.
Usually only happens when the car is cold ... sometimes takes 2 or 3 miles to show up ... sometimes only takes 1/4 mile to surface.

Has done it as many as 3 times in the first 5 miles of driving.

Anyone else had similar symptoms or know of a resolution to the problem?? Thanks for any advise!

 

[c4c5specialist]

Hi there,
I am sorry for your condition, but there are a total of 39 different reasons for the reduced engine power. What codes were in the PCM and the TCS????? Codes are critical to what is happening, and cannot be diagnosed without them.
Please post codes, and we can assist you in pointing you in the correct direction for your condition.
Allthebest, c4c5

 

[FergieKC]

Thanks for the reply c4c5,
Unfortunately, you are talking to an ignorant consumer.
I do not know how to accurately get the codes. I did read a procedure on another forum on how to extract them, but after trying I only got a couple of meaningless ones out (according to the dealer I spoke with).
Can you give me idiot proof directions on how to get the codes to display?
BTW, the dealer said that they would hook me up to their diagnostics for $90, but were pretty sure that they may not be able to determine the exact problem or solution. That kind of confindence did not inspire me to part with the Ben Franklin.
Maybe they were unsure because of the 39 alternatives that you mentioned!

Will the codes eliminate most of the 39 choices, down to a managable mystery?

Thanks in advance for your advise?
FergieKC

 

[DRTH VTR]

UNDERSTANDING CODES

I bought a set of service manuals for my '97 A4. It was the best money I spent. I am not brave enough to tackle any major repair, but some of the minor stuff is easy to do when you can see how things go together and where the fasteners are. It also says what each of the trouble codes are. Those codes can be read with the driver information center (DIC) if you know the secret handshake.

 

[c4c5specialist]

Thanks for the reply c4c5,
Unfortunately, you are talking to an ignorant consumer.
I do not know how to accurately get the codes. I did read a procedure on another forum on how to extract them, but after trying I only got a couple of meaningless ones out (according to the dealer I spoke with).
Can you give me idiot proof directions on how to get the codes to display?
BTW, the dealer said that they would hook me up to their diagnostics for $90, but were pretty sure that they may not be able to determine the exact problem or solution. That kind of confindence did not inspire me to part with the Ben Franklin.
Maybe they were unsure because of the 39 alternatives that you mentioned!

Will the codes eliminate most of the 39 choices, down to a managable mystery?

Thanks in advance for your advise?
FergieKC

Hi there,
Well, first of all, if the symptoms, and the light were on in the last 50 drive cycles, you will find codes that will correlate to the failure.
Here is how to retreive them.

Turn ON the ignition switch, engine OFF.
Press the RESET button to acknowledge any warning messages present.
Press the OPTIONS button on the Driver Information Center (DIC) and hold.
While holding the OPTIONS button press the FUEL button 4 times within a 5 second period.
System will first enter automatic display mode followed by the manual display mode.

Have a pen and pencil ready, as they come quickly.
You are only concerned with 10-PCM and 28-TCS.
Please let us know what you have, and we can proceed.
Allthebest, c4c5

 

[FergieKC]

Hello c4c5,
Sorry for the delayed response, been traveling alot last week.

Your directions were idiot proof but a pen & paper were still too slow; those codes come fast!
Handheld tape recorder finally got me results.

PCM
P1125H
P1281H
P1571H

TCS
C1278H

That was all of the PCM / TCS related codes.
What are all of these?
IPC
B1527H

LDCM
B2282H
B2284H
B2272H
U1064H

RDCM
B2239H
B2253H
B2205H
B2283H
B2285H
U1064H

Thanks for your advise.

 

[c4c5specialist]

Hi there,
Your first code, 1125 shows a problem with your accelerator pedal position sensor, located at the gas pedal inside the car.
Your 1281 is along the same lines, but could just be a latched code, meaning that the code comes along with the 1125.
Your 1571 is classified as a normal condition on 97 Corvette, as long as it is H. Do not concern yourself with this one.
Your 1278 in the TCS is a result of the PCM codes and can be ignored.
So basically, you have to diagnose the gas pedal sensors, and the throttle actuation control module.
We have had problems with the TAC module in 97- early 99.
It is very in depth, and at this time, I would strongly recommend that you seek out a Corvette tech and have the car correctly diagnosed.
Please keep us posted, c4c5

 

[my1corvette]

Reduced engine power

Another cry for help from the c4-c5 specialist !!! The same thing happend to me , I took my car out of winter storage fired it up and drove it for about an hour .No Problem , the next day when I started the car it was like it was only running on a few cylinders and I had the message "reduced engine power " and "traction control" the check engine light and traction control was on . I turned the engine off once and the traction light went off , I turned the engine off the second time and the reduced engine power was gone and also went the check engine light . I took it for another one hour ride and nothing happend . I drove the car two more times since then and everything seems to be normal.
I took the codes of the car anyway and this is what I had
10-pcm P1516H
28tcs C1278H
can you give me any advise or since everything seems to work fine shall I just ignore that it happend ????
thanks a million
John

 

[c4c5specialist]

Re: Reduced engine power

Another cry for help from the c4-c5 specialist !!! The same thing happend to me , I took my car out of winter storage fired it up and drove it for about an hour .No Problem , the next day when I started the car it was like it was only running on a few cylinders and I had the message "reduced engine power " and "traction control" the check engine light and traction control was on . I turned the engine off once and the traction light went off , I turned the engine off the second time and the reduced engine power was gone and also went the check engine light . I took it for another one hour ride and nothing happend . I drove the car two more times since then and everything seems to be normal.
I took the codes of the car anyway and this is what I had
10-pcm P1516H
28tcs C1278H
can you give me any advise or since everything seems to work fine shall I just ignore that it happend ????
thanks a million
John

Hi there,
This is a tough one, as this shows that the TAC module does NOT see what it wants to see at the throttle plate position sensor.
Your 1516 could be any one of 3 different reasons for this failure. It could be a chaffed wire, defective TAC module, or a bad throttle motor.
Once again, a very tough call over the internet, however, I would have it diagnosed professionally on this one.
Allthebest, c4c5

 

[FergieKC]

Here is the latest development in my mystery.
I got this Bulletin from one of the local dealers.

Obviously, Condition #2 applies to my situation with Code P-1125 accompanied by P-1281, but 3 dealers I have phoned & emailed my codes & this bulletin to cannot tell me with any confidence that they can fix it.

One said they will re-flash everything for $90, but could not tell me what "Normal Startegy Based Diagnostic" or "Diagnostic Software and Calibration in the TAC-Module were not Optimally Utilized" means.
Really makes me wonder if they know what the hell they are doing! Can't they just call up the Bulletin or other documentation & see what these terms mean?

Does "not Optimally Utilized" mean that the software was wrong in the first place (in which case it should be a Recall) and why did it take 5 years & 30,000 miles to flake out??

FergieKC

REDUCED ENG. POW. MESSAGE ALONG W/ PARTIC. PWRTRAIN #87-65-16
SUBJECT: REDUCED ENGINE POWER MESSAGE ALONG WITH PARTICULAR POWERTRAIN
TROUBLE CODES (INSTALL NEW TAC-MODULE IF STRATEGY IN SERVICE MANUAL FAILS)

MODELS: 1997-98 CHEVROLET CORVETTE WITH 5.7L V8 ENGINE (VIN G - RPO LS1)

CONDITION #1: INTERMITTENT REDUCED ENGINE POWER EVENT, ACCOMPANIED BY
P-1516, OR P1518 TROUBLE CODES.

IF A SITUATION ARISES WHERE A P-1516 TROUBLE CODE IS ACCOMPANIED BY A

P-1120 AND/OR P-1220 TROUBLE CODE, THIS SERVICE BULLETIN DOES NOT
----------------------------------------------------------------- APPLY. IN
THESE CASES THE TECHNICIAN MUST USE THE NORMAL STRATEGY
------------------------------------------------------------------ BASED
DIAGNOSTIC. -----------------

CONDITION #2: INTERMITTENT REDUCED ENGINE POWER ACCOMPANIED BY TROUBLE CODE
P-1125 AND ANY OF THE FOLLOWING TROUBLE CODES:

P-1276 P-1281 P-1286

CAUSE:

CONDITION MAY BE DUE TO DIAGNOSTIC SOFTWARE AND CALIBRATION IN THE
TAC-MODULE WERE NOT OPTIMALLY UTILIZED.

CORRECTION:

IF THE ABOVE CONDITIONS CANNOT BE CORRECTED USING THE NORMAL STRATEGY BASED
DIAGNOSTICS LISTED IN THE SERVICE MANUAL, INSTALL THE NEW TAC- MODULE LISTED
BELOW.

PART INFORMATION:

NEW TAC-MODULE PART # 25319443

PARTS ARE EXPECTED TO BE AVAILABLE ON APRIL 6, 1998 FROM GMSPO.

WARRANTY INFORMATION:

FOR VEHICLES REPAIRED UNDER WARRANTY, USE:

LABOR OPERATION: J-5582 LABOR TIME: 0.5 HR

FIGURES: 00 ATTACHMENTS: 00

 

[c4c5specialist]

HI there,
If they cannot say that they can diagnose it, find someone who can.
This is NOT a guessing game, and Corvette service departments are the last line.
I am sorry for your conditions, but in this case, I think someone is afraid to work on Corvette.
Allthebest, c4c5

 

[my1corvette]

Engine power reduced

Hi , well I had my car checked out as you suggested to get to the problem with my 1516 code , They say its the trottle motor at a price ticket of $499.00 just for the part .
I guess if you want to play you have to pay .
Do you know what could have caused this problem ? I don't race and keep very good care of my car .
thanks again C4C5 specialist
regards John

 

[knightvette]

accelerator pedal sensor

I have had the same trouble with my 98 as I see here. Auto zone says it is a accelerator pedal sensor. I want to try to replace it myself but I don't know where it is located. If anyone knows will they answer me Thanks