Just driving around on Sunday enjoying a great day here in Dallas. Stopped at intersection and when light changed and I gave the car some gas I got reduced engine power and service traction control system. Shut the car down restarted and got the same messages. Shut it down again and pulled the codes while blocking traffic.

TCS C1278H and PCM P1518H

Car restarted and everything was fine except for a check engine light. I reset the codes and the engine light went out when I reset the pcm code.

Please tell me what this was?

 

Can't tell you what it was but here is what those two codes mean:

C1278 TCS Temporarily Inhibited by PCM
P1518 PCM to TAC Module Serial Data Circuit

I have no idea what TAC stands for. Someone will chime in soon. :cheers:

Patrick :seeya

 

The electronic throttle control uses multiple sensor inputs and checks them for disagreement. Disagreements trigger this reduced engine power mode in order to avoid miscommanded throttle positions.

If it happened just this once, I might ignore it. :crazy: If it happened again, I'd have it looked at. :smash: Could be something simple like connectors or something more complicated. I think I recall hearing about TSBs for the TAC/TCM on some models.

 

There is an updated TAC module for that concern :yesnod:

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.
:seeya