Gents:

2001 convertible, MN6

While recently driving on freeway, had a sudden illumination of dash lights along with “Reduced Engine Power” but engine did not just reduce power it stopped. I coasted quickly from fast lane to exit. All electronics functioned and car would turn over as if starting but would not fire. There was fuel pressure. Each time I turned the key the same “Reduced Engine Power” would show up on DIC. Engine would not start. Codes were as follows:

P0102HC, P1518HC, P1637H, C1278H

I could clear the codes but P1518 would usually persist. After 5 minutes or so, I turned the key, “Reduced Engine Power” DID NOT return and car started up normally. A short distance later it repeated itself and stalled out. Waiting a few minutes and clearing DIC would get me going again....but I can count on a recurrence. I also get “Service Engine Soon” messages. I have had a similar issue in the past and it resolved nicely when I switched out the ignition switch. I kept and repaired the original switch a la Bill Curlee and today swapped them out. Alas, the car started, Idles for a few minutes, then threw the “Reduced Engine Power” and then stalled out and refused to re-start. Same codes. Interestingly I can clear them except for the P1518 which recurs at key in despite engine not starting. For some time now I have noticed the DIC voltage reading anywhere from 12.1 to 14.1. Up until recently no codes but I would notice the voltage drops at night as the lights would dim slightly. When it popped back up to 13.9-14.1 they would brighten back up. The starter wires are pristine and the terminals appear as if new. As my car has been sitting for 2 weeks now my battery is at 11.9 so I will charge it as I await the combined wisdom of my fellow forum Bretheren, but I did measure voltage, and from alternator POS post it is 11.9, at battery POS it is 11.9....yes, I know its dead, but voltage measuring out the same (albeit with engine off). Today it is also flashing the “Security” light and TONE bell with key out and door open (as if lights were left on, but they are not).
These cars are such fun........could use some help.

 

https://www.corvetteforum.com/forums...post1589832807

 

Reduced Engine Power Mode

When the PCM detects a condition with the TAC system the PCM may enter a reduced engine power mode. Reduced engine power may cause one or more of the following conditions:

■ Acceleration limiting--The control module will continue to use the accelerator pedal for throttle control; however, the vehicle acceleration is limited.
■ Limited throttle mode--The control module will continue to use the accelerator pedal for throttle control; however, the maximum throttle opening is limited.
■ Throttle default mode--The control module will turn off the throttle actuator motor and the throttle will return to the spring loaded default position.
■ Forced idle mode--The control module will perform the following actions:
o Limit engine speed to idle by positioning throttle position, or by controlling fuel and spark if throttle is turned off.
o Ignore accelerator pedal input.
■ Engine shutdown mode--The control module will disable fuel and de-energize the throttle actuator.


I dug this up on a Chevy Avalanche forum but a TAC module is a TAC module and I suspect they are similar in programming. I was unaware of the “Engine Shutdown Mode” and find it unsettling. It shut off my motor while in the fast lane in moderate traffic.......not such a safe mode, but it is what it is. Given the persistent code will start with troubleshooting the TAC.

Thanks for the input.