I have 97 vette and this morning while trying to pull out of my garage the engine power loss light come on and the car would not move at all. Anyone out the ever have this problem before and what was the problem. I talked to a gm mech that i know and he said that it could be any number of things but i want to know what i could check before i have it towed to the shop and it get hit with a huge bill

 

I assume you mean a "reduced power message", as opposed to a "engine power loss" light..

start with your codes:

http://www.c5forum.com/ayc/dtcdic.php

 

First off read the codes on your dash.

 

Read and post DTCs

READING YOUR Engine Diagnostic Trouble Codes (DTC)

This procedure should be carried out any time you experience a problem with your C5. Most inexpensive store bought aftermarket code readers will ONLY read power train DTC’s. Reading the DTC’s with the C5 built in code reader will allow you to read ALL the modules in the vehicle.

The Diagnostic Display Mode is entered with the following procedure:
1) Turn on the ignition but don't start the engine.
2) Press the RESET button to turn off any warning messages. (i.e. door open, trunk open ect)
3) Press and hold the OPTIONS button
4) While holding OPTIONS, press FUEL button four times within a 10 -second period.

Initially, the on-board diagnostics go into an Automatic Mode which will cycle through each module and shows diagnostic codes in a pre-set sequence: PCM - TCS - RTD - BCM - IPC - RADIO - HVAC - LDCM - RDCM - SCM - RFA. All codes will be displayed for each module. ( i.e. PCM = 4 codes) If none are present in a given module, you will see No More Codes on the display.

There are two types of diagnostic codes, Current and History designated with a letter suffix, “C” or “H”. A current code indicates a malfunction is present in the module displaying data. A history code indicates a problem existed sometime in the last 40 or 50 ignition cycles. When not accompanied by a current code of the same number, it's potential evidence of a previous problem, now resolved, that was not removed by clearing the codes. More likely it's an indication of an intermittent malfunction.

Intermittent codes are the most challenging of the diagnostics. An intermittent code may have happened once, may have happened more than once but is inconsistent or may be happening on a regular basis but not at the time the codes are displayed. History codes can also be caused by a current malfunction in a system that is not operating at the time codes are displayed. An example is the rear window defogger which doesn't operate until the Body Control Module detects engine rpm. For history codes set by a module that does not operate with the key on and engine off, a special diagnostic tool called a Scan Tester is necessary to properly diagnose the malfunction.

Once the system has displayed all modules, it goes into the manual mode which allows selection of each module using combinations of Driver Information Center buttons. Manual mode can also be entered during the automatic sequence by pressing any button except E/M. Once the display shows Manual Diagnostics, select a module by pressing the OPTIONS button to go forward or the TRIP button to go back. Once a module is selected, a code is displayed, and if more than one are present; press GAGES to go forward or FUEL to go back.
To exit the diagnostic mode at any time, press E/M. If you want to erase codes in a given module, press RESET To reset the codes once in manual mode, press and hold RESET until it displays NO CODES Press OPTIONS to go to the next module. Repeat the steps until you have reset the codes in all the computer modules.
NOTE!! Only reset the codes IF you want to - it is NOT necessary to do this. Clearing a code does not repair a problem. You are simply erasing the evidence of it in the module's memory. If you clear the code/s, and extinguish the Check Engine Light, your emissions status ready will NOT allow you to pass an emissions test until you have completed the required driving cycles. There are a few body module DTC’s that if set will prevent the module from operating properly. Once the DTC is cleared, the module will return to full function. This is not true for power train DTCs.

If you have never read and cleared your codes, there will probably be a lot of old history DTCs. It is recommended that you clear your codes and see if any come back during a driving cycle. Those are the ones that you need to concentrate on diagnosing.

Once you have the codes, the next question is: What to do with the information?
First, consult the factory service manual. Any serious C5 Do-It-Yourself owner should invest in the Corvette Service Manual of the appropriate model year. The Service Manual is really a requirement if you want to understand and work on your C5.

You can read the DTCs while the engine is running. If you turn the engine OFF and then back ON, that can clear some DTCs that may be important with identifying a problem. One example is a Misfire DTC (p-0300) If the engine is shut down, the DTC will clear.

These are some very good C5 Diagnostic Trouble Code (DTC) explanation web sites!!! They also explain how to read the DTCs

Here are some very good sites that explain what DTC mean:

http://www.gearchatter.com/viewtopic11755.php

http://www.obd-codes.com/trouble_cod...d-ii-codes.php

Make sure to include the H or C suffix when you post your DTCs!!

 

Bill, maybe you should put this in the Tech Tips and just link people to it?

 

Actually, I think they need to set it up as a quiz you have to pass before becoming a member!

 

The stars must have aligned. I had the same problem in a '98 coming home from work last night. "Reduced Engine Power" and "Traction Control Failure" indications on the DIC. The engine transitioned to low power mode, which really sucks...nothing like driving a Vette with a 35-40 mph top end. Failure mode seems electronic in that it drove ok for a few minutes this morning, but eventually the same problem occurred. I was hoping it was a battery problem (the computers tend to be very sensitive to low voltage as it demonstrated to me with a column lock-out soon after I bought it in '05 that was fully resolved with a new battery), but I'm not sure that's the case.

Codes in memory are P1221H and P1515H (throttle position sensor correlation and control module throttle actuator position performance) and C1278H and C1281H (TCS inhibit and handling sensor, steering sensor uncorrelated).

Anybody have any ideas on the potential source for the problem?

Thanks

 

Been there done that! Yea,,it sucks.

Most REP problems happen because the throttle by wire system is having issues. However,,,97 and early 98 C5's had a documented problem with faulty TAC (Throttle Actuation Control) modules.

My 98 had that issue. You can try to RESET the DTCs when it happens and sometimes it will resolve the issue enough to get you home. I could pull up the DTCs and clear them on the fly and not even have to pull off the road.

Keep that in mind. You can order a new TAC module form Gene Culley www.gmpartshouse.com They were $230 when I ordered mine back in 2000. Its also a plug and play module.

Heres a picture of it on top of the PCM in the passengers fender well Its the black plastic box:

 

Thanks Bill. Appears the culprit was the battery once again. Got it checked, replaced (3rd since '05 and the last two were free, but that's another story), and the problem has disappeared for now. My two related experiences say to check the battery first, regardless of the specific code. Kind of amazing that GM incorporates computers with (apparently) little or no health and status checks on proper operating voltages.

By the way, the battery had plenty of capacity to start the car, but I'd noticed in the last week that it was cranking a little slower than normal. So it appears that it doesn't take much battery degradation to create havoc.

Thanks again (for all the good info you've provided),

Chris