ok if someone can fix this car or resolve this problem i swear ill give dinner certificate anywhere you like! this is ongoing since almost two years the car has been a nesance. you can read all the other messages from me. its a 92 and i have this electric gremblin. these are the symptoms: the car will crank, start but after 1/2 second or so quit. then sometimes just crank, know the key is every once and a while the car will start right up. at this time even the tech2 computer is reading nothing is wrong. know on the dash the service asr is on all the time, the sys and security start flashing, at this point i know the car will not start if a turn it off. this is only when car is running. if is doesnt start when key is ignition it does the same thing. know ive replaced the coil, bypassed the tach filter, optispark, ecm, bcm three times! and even bypassed the hvac computer and asr, just so the bcm and ecm can communicate, know my mechanic cannnot get these to computers to communicate at all, today it started for a couple of minutes, hurried up got tech2 and it communicated with both just fine, but then all off the sudden car started to sputter and tech2 lost communication with bcm and car died and back to normal start and die, start and die. now i can keep it running when i start it by jiggling the gas, but the car runs like ****and will immediately stall when i let off! at that time there is no response either to the tech 2. mechanics telling me there is a short somewhere. i was told today about the ignition driver or module and i was about to replace that but thats when the car started for me for awhile so i think i should not bother right? i just bought another dash with all wires from ebay just want all opinions before i gut this dash and car and replace it or sell it for dirt cheap,,losing faith need help quickly.....thanks for reading

 

I don't have a clue as to the problem but seeing what all you've done I believe the next money spent would be to talk to Gordon Killebrew. He has a website and the phone number to call is there. He accepts credit cards and charges by the minute. Might be the best money you could spend. Just type his name in your search and click on his website link.
Good luck, don't give up.

 

you already have a thread open with this problem... it would be best for everyone involved if updates and status changes are kept in one place.

Also, allow me to introduce you to the enter key... A very useful device when explaining a complex problem.

 

Have you tried talking to Gordon Killabrew? Desperate times call for desperate measures. He charges for his telephone time but everyone I know with a way out flaky problem got the help they needed from Gordon. I do not have his number available but hopefully someone will post a link. This guy has wiring diagrams committed to memory!

 

Gordon Killebrew is the real deal - this guy knows the C4 forwards and backwards.
PHONE CONSULTATION
After Gordon retired from GM's Corvette plant's Action Center, where he told GM's Tech Center and Dealers how to fix the Corvettes, he started For Your Car, Inc. to help the Corvette owners and shop technicians solve their troubleshooting problems by calling him on his consulting line 1-800-39-83883 (800-For Your VETTE). His fee is $10.00 per call, plus $3.00 per minute, while you talk with him. It is charged to your Visa or MC that you supply when you call. He wants to help you solve your problem ASAP and save you money

 

Have you considered anything fuel related........like the pump? Have you put a pressure guage on the fuel rail at all while the car is acting up.

 

yea checked fuel and pump its fine besides i dont think that will mess with your asr light or sys or security flashing while driving think its definately electric. i think?

 

have you checked all your grounds??

 

sounds like you arent getting enough fuel!
because you car is not getting enough fuel at idle!!!!!!!!! and for it to stay on you have to give it more fuel.
lets start with most likely to less likely!


1. start with checking the fuel pump make sure it works 100%
2. o2 sensors!!!
3. then check all the fuses!
4 check the ingintion wires/spark plugs to make sure they work.
5. pke system
6. grounds on the car hooked up.



the dash doesnt matter!! that jsut shows you wants going on with the car...has nothing to do with how it runs.

 

also how many miles on it and auto or 6 spd
stock?

if you leave it on or dirve it, once you know that it wont turnn back on if u turn it off, will the car die?

 

It sounds to me that you have a problem in the serial bus wiring between the CCM and the PCM or ECM. Those would be the first places for me to check out. Tell your guy to isolate the serial communications circuits. Bypass them direct if necessary with a known good connection that way you can at least eliminate any problems with communications between the devices. Also check the fuel enable circuit between the CCM and the ECM or PCM.

 

You don't say what ASR code was set. Even if the car doesn't run, you should be able to get a history code.

I also have a '92 and I'm dealing with a similar issue, although not nearly as severe. My car died once in traffic. After about a minute, the car restarted and ran fine all the way home, but with the Service ASR light on. I got a code 62, which is a tach pulse code fault. Basically, the signal from the ignition system to the EBCM (brake computer) was interupted. The factory service manual states that a short to ground on the ignition side of the tach filter will set a code 62 and cause a no-run condition. Shorts between the tach filter and the EBCM can cause the car to run poorly.

I performed a cursory check of the wiring between the coil/ignition module and the tach filter and didn't see any problems. I'm going to unwrap the wires and check them more carefully, but if they look ok then I plan to replace the tach filter and the ignition module. The tach filter is available from Ecklers for $40, and the ignition module is $100. Either of these parts can fail and cause the problem.

That's where I'd start if I were you. I bet your problem is in the tach pulse circuit. Check the wiring between the coil/ignition module and tach filter very carefully. This stuff is at the front of the engine on the passenger side. The tach filter is a small square black box in the wiring harness. If the wiring looks ok, I'd replace both of those parts before I started ripping out dash wiring. Also, I don't know how you're "bypassing" things, but with the way the computer systems are integrated that's likely to cause more problems than it will solve.

If none of this works (or you can do it first), calling Gordon Killbrew is good advice. Good luck!

 

I agree, it sounds like something related to the serial bus or the computers on the serial bus.

First, disconnect the C68 climate control computer (if you have one) and the ASR/ABS computer connections -- the vehicle will run without these computers temporarily. By disconnecting these computers, the only ones left are the CCM and the ECM on the serial bus. Ignore any ASR, ABS, or climate control flashing trouble lights -- they are now disconnected.
If there are no problems after disconnecting those two computers, connect them back one at a time until you find the problem.

If the problem still exists after disconnecting those two, you probably have:
1) An intermttent short on the serial bus -- disconnect all the computers (ASR/ABS, C68 climate control, ECM, and CCM) and put an ohmmeter on the serial bus and wiggle the wires to see if it is grounded.
2) An intermittent problem in the ECM -- if your vehicle is earlier than a '94, this is my guess as to the problem.
3) An intermittent problem with the CCM -- the CCM is pretty reliable and it would be unusual, but not impossible, for it to be the problem.

The thing to keep in mind is there is an encripted security code "handshake", via the serial bus, between the CCM and the ECM at startup. The CCM is responsible for verifying the ignition key "pellet" resistance and telling the ECM that it is valid -- this is where the handshake takes place. If the handshake fails, the engine won't start.
Also, the CCM is the master computer and the rest are slaves -- the CCM is in control of the communications on the serial bus.

If you decide to guess and replace something and your car is earlier than a '94, I suggest the ECM because it is frequently the problem -- but, I don't encourage guessing.

And, if you still can't find the problem, contact Chris Petris -- he writes technical articles for Corvette Fever magazine. He's good at these computer problems.

Tom Piper

 

Have you checked the resistance on each injector? I had 1 bad injector (created an electrical short) on my '91 - car would run for 2 seconds then quit.

I had traded out my ECM, ignition module etc... I even took it to a local Chevy dealer and they couldn't figure it out.

For what it's worth.

 

Just thought of some other things to keep in mind.

Once the engine is started, the ECM should be able to keep the engine running by itself -- if the CCM looses communications with the ECM after the engine is running, the "SYS" will flash, the "Securtiy" light will come on, and the ASR light will come on, but the engine should run fine until the next time you try to start it. Since you are saying the engine does not run fine once it is running, I would look at the ECM, wiring and power to the ECM, etc. Even though the CCM is the master computer, once the engine is running, the ECM should be able to run the engine standalone.
This suggests a ground or power problem to the ECM or a defective ECM.
Plus, since you are loosing communications between the Tech2 and the serial bus at the same time the ECM can't keep the car running, this suggests that power has failed to the CCM too.
Check your power and grounds in the entire car. There can be no serial communications without power to the computers that supply the communications.

Look at the fusible links under the battery and make sure the connections are tight.

Tom Piper

 

Boy!! You guys must be hungry

 

I agree. I've spent the last twenty years working on flight simulators, and most of the really flakey problems are caused by bad ground connections.

Good luck

 

ok thanks for the responses, but to answer these questions, alright the fuel pump is fine and fuel system. ive already did the serial link to just the ecm and ccm without the asr and hvac system involved no change.
hers the kicker every no and then id say every 30 trys to start it the car will fire right up and run awesome, so thats why i havent changed the ignition module, i figure if it runs fine every once in awhile it cant be bad. as for the tach filter, i bypassed it by taking the two white wires and tying them together, still nothing, so put that back the way it was. now when the car does start and run fine, if i take it for a drive eventually the asr light and the security and sys will start flashing, that usaully means it wont start again if i shut it down, but its wierd cause if i wait 5 minutes or sometimes 8hrs the car might refire.
but lately the car hasnt been starting and staying running it has gotton worse, you guys are talking about these grounds where do i look for these? and remember the ecm is new and the ccm is new, they communicate if the car is running fine, but they lose contact with each other when the car wont start.
when i say the car wont start, it means the car will turn over and start, for a brief minute and die, so it starts but something tells it to shut down instantly. now i can keep it running if i catch it before it stalls but i have to stay playing on the gas pedal, it runs like ****, like its on 5 cylinders, popping and spitting, and once i let off it stalls,
i know for a fact it needs a o2 sensor it runs rich, but that cant be causing this electric problem, or the ignition module because it will run fine every once in awhile! maybe im wrong, but i think its the wiring between the ecm and ccm, or like it has a short or bad ground. where are these grounds im looking for??? again thanks for the insite everyone!!!

 

As I stated above:
Look at the power terminal block that is behind and below the battery.
This is where several fusible links are connnected. These fusible links supply the power feed to many of the circuits in the car.
Make sure the connections are not corroded or loose.

There are ground connections on the back of the engine behind the oil filter where the engine mates to the transmission.

And, you are saying "new" ECM and CCM. Are you sure they aren't rebuilt/refurbished?
When there is an intermittent problem in these units and the technician can't get the problem to happen on the bench, guess what happens? They are considered OK and sold as rebuilt/refurbished. So, don't count them out completely.


Tom Piper

 

I agree, check for a bad ground wire somewhere. Im somewhat new to mechanics but I've been dealing with electronics long enough to know the symptoms. Even if you think it's good check it anyway at a different location.