Welcome to the Corvette Forums at the Corvette Action Center!

Help! Hard starting, runs at low idle


Jul 11, 2014
1997, silver
Hello to everybody. Having a problem with my 1997 corvette ever since I got it back from the body shop. I know this is going to be long- winded but please bare with me i just want to let you know what been happening. They painted both front and rear bumpers. They disconnected the battery a few times. Picked the car up At the body shop and my A/C control stopped working. It looks like it works but no blower [I can hear the compressor engaging]. If I play with the blower control buttons I can get it Blow. Some times low sometimes Hi. Its erratic. After a couple days when starting the car it would crank but not start. It does start after a while but starts in low idle and I have no throttle. Only low idle, almost stalling. After trying a local shop I finally brought it to a Chevrolet Dealer. After two days they told me I needed A Neutral saftey switch??? They said they could not produce my starting problem and there computer is telling that my neutral saftey switch is bad. Went to dealer to talk to service manager and we both agreed if the car cranks in park and neutral and doesn't start in gear maybe the switch is ok. I told him to keep the car for a few days and I was sure the car would not start. After 7 days they told memy fuel pump relay has low voltage going to it so i would have to replace the PCM. And the A/C control also needs to be replaced. To the tune of $2200. Well I did not have the bucks at the time so I took the car home. It did not start in the parking lot. until the service manager came out and erased the fault codes. Went home went on line and found a relearn procedure for the pcm. The car has been running fine for 18 months, then a couple weeks ago it starting doing the same thing again. The diagnosis codes are, 10 PCM, P1518 H C, P1571 H, TCS 1255 C, 1278 H, U1016 H U1096 H. If I erase the P1518 code the car runs fine all day. If I leave it for a while codes come back and I have to erase again to get it to run. I guess I'm confused If the PCM is NG how can I erase the codes and drive it all day and it be fine? To me it seems like there is something other than the PCM thats not working right. But I have been known to be wrong and a little bone headed at times. It would be great if someone can help. Thanks for listening.
DTC P1518 is a fault with the serial communication line between the PCM and the TAC Module. This means the engine computer and the throttle actuator controller are not in communication and if the PCM and the TAC Module don't talk to each other, it's hard for the engine to run much less run properly. The H and the C mean the problem has occurred recently and was occurring when you read the codes.

DTC P1571 is a fault in the circuit which links the PCM with the EBTCM and carries the desired torque signal from the EBTCM to the PCM when wheelspin is detected and the EBTCM wants the ECM to reduce engine power to stop the wheelspin. The H means this fault as occurred in the recent past but was not present when you read codes.

DTC C1255 is fault inside the EBTCM. The C means it was occurring when you read codes.

DTC C1278 sets if the PCM temporarily inhibits TCS when TCS is malfunctioning.

DTC U1016 sets if the PCM and the Body Control Module (BCM) have a lapse in communication. H means the lapse has happened in the past was was not happening when you read codes

DTC U1096 set if the BCM and the Instrument Panel Cluster (IPC) have a lapse in communication. H means the lapse has happened in the past was was not happening when you read codes.

A general statement: You likely read codes with the engine off so, by definition, some of those faults would not be present.

Before you do anything, I'd make sure the battery in the car is in excellent condition and there are no problems with battery cables.

My gut feeling is you have one, two, three, four or all of five problems.

1) Problems with wires and connections in the various circuits which link the PCM, TAC Module and the EBTCM and allow them to exchange information.

2) Problem with wires and connection between the PCM and the BCM

3) Problems with wires and connections between the BCM and instrument cluster.

4) A problem with the connections between the electronic brake and traction control module (EBTCM) and the brake pressure modulator valve (BPMV) which bolt together.

5) A faulty EBTCM.

You can do the "relearn procedure for the PCM" until the cows come home, but that will not solve the problems you have.

If you are familiar with basic electrical system diagnosis, you have the Factory Service Manual for a 1997, you have a DMM and a professional grade scan tester which will read not only PCM but EBTCM and BCM, you may be able to fix those problems yourself.

If you lack the dealer-grade scan tester. You may be able to do some of the diagnosis/repair work as far as checking wiring, connections and grounds by visual inspection or by using a DMM but you need the FSM for its wiring information.

If you don't have the above, you need a dealer service department or an independent service vendor with good vehicle electronics and diagnostics skill.

If you don't have the skill/resources to fix those things and you don't have the money to pay a service facility to repair them, well...hate to say this, but;shrug

...you're screwed.
I agree with Hib. If I were you I would look at the PCM and TAC modules which are below the battery. You need to make sure the connectors are clean and not corroded and the wiring looks good. I can help you with continuity check info if you need help.
As "dadaroo" suggests, you need to "get a visual" on those components. This may require, not only removal of the battery, but removal of the battery "box" as well.

C5 has had problems with corrosive material dripping or falling off the battery and onto the wires and modules under the battery.
Hib, not to hijack this thread, but do you (or anyone else out there)
know of an aftermarket solution that addresses this issue? I would be very
interested in something that would prevent troubles like this down the road.
Thanks, :thumb
Andy Anderson :w
HIJACK OVER- We now return you to your regularly scheduled thread.............
First, let me say that my earlier post did not definitively state that the cause of the problems "ny2fl04" is having are caused by battery leakage. I was just suggesting that as a possible cause. It's also possible his/her battery is not leaking anything and the problems are caused by something else.

Ok...."aftermarket solution"....

Well....my "aftermarket solution" would be good maintenance. That is, you inspect the battery once in a while to see if problems are developing, such as: the case is leaking.

In my earlier post, I really didn't describe the problem correctly. The issue is, actually, defective batteries leaking acid onto the ECM which is right beneath the battery.

An "aftermarket solution" would be to re-engineer the engine controls harness then move the ECM to a different location but that's hardly practical for anyone at the DIY enthusiast level, so we're back to: good maintenance. Regular visual inspection of the engine compartment looking for problems. Do that and you'll likely catch a leaking battery before serious damage is done.

Another solution might be to replace the OE Delco or other cheap battery with a really good battery such as an Odyssey which won't leak.
Last edited:
A lot of people access the PCM area by removing the right front wheel and removing the plastic wheel well liner. There are some small screws that go in "upwards" at the rear of the liner also.
Hard starting

Thanks guys for all the info. I just pulled the PCM and the TAC this morning. Some of the connectors on the PCM look a little compromised. Found A company called SIA in Illinois that will check the PCM and repair anything wrong for $152. Anybody deal with them before? Since i'm not sure of the PCM I'm starting there.
If it were me I would try to see how it runs after cleaning the connections. If I knew which pins looked bad I could provide more info.

I looked at the SIA website and they appear to be legit.

Not sure if I would try seeing if it was the TAC module first or not but one has to start somewhere.
Thanks guy,s for all your info. I did send out my PCM. Got it back about a week ago. Company found a lot of corrosion outside and inside. Cleaned it all up and tested it. Found nothing else wrong with the PCM. Charged me $89.00. Cleaned all wire harness connections and re-installed the PCM. Driving the car for a week. No codes runs great.:beer

Corvette Forums

Not a member of the Corvette Action Center?  Join now!  It's free!

Help support the Corvette Action Center!

Supporting Vendors


MacMulkin Chevrolet - The Second Largest Corvette Dealer in the Country!

Advertise with the Corvette Action Center!

Double Your Chances!

Our Partners

Top Bottom