Falcon2000

1994 C1500 5.7 Suburban automatic. Problem is intermittent and occurs occasionally while driving under normal conditions. What happens is that the ignition system will completely cut out. When this occurs the instrument panel gauges (Oil & Temp) freeze at whatever condition the engine was operating at, and the Volt meter drops to zero. I may even recall the speedometer freezing in place. When attempting to restart, the engine will turn over. but the first attempts to restart usually fail due to no spark. One thing to note is that the gauges will not reset (oil press to 0 and temp to current engine temp) and the voltmeter still registers 0 volts when the ignition key is turned to on. The first indication I get that the the engine will restart is that the gauges all reset when I turn the key on. When this problemfirst started the engine would usually restart after several attempts, now the time between the failure and a successful restart could take more then a day. The other thing to note is that, in most cases when I finally get the engine to start, as soon as the transmission is taken out of PARK and placed into gear the fault immediately occurs along with the gauges freezing again, and then I have to sit and wait from anywherefrom acouple of minutesup to severalhours before it may start again.
The truck has a new ignition system including distributor and new coil, and a new ignition switch, all of which had no effect on the problem. I swapped the ECM with the ECM from my 94 Silvarado andthe ECMfunctions correctly, but has no affect on resolving the problem.

shawnvw

So by swapping the ECM you fixed the problem???

Falcon2000

What I meant to say was that the ECM tested OK and was not the source of the problem.

shawnvw

It really sounds like a poor connection somewhere. Start by removing,cleaning, and tightening all grounds to the body and to the motor. Also have a look at the Starter wires. I believe there are 2 or 3 wires in total at the battery lug of the starter. Again, pull it apart, clean it up, and re-connect

Falcon2000

I'm in the process of cleaning up alll the connections, but so far the ones I have checked are good. I'll let you know.
If all of the connections check out OK I think the next step will be to disconnect the ECMand comparereadings on all of the inputs to the ECM in the Suburban with all the inputs to the ECM on my 94 Chevy pickup. They should all be the same.

dgbrooks

Did you figure out the problem? I'm having almost identical issues with my 2001 and 2000 Chevy Silverado and Suburban. The Suburban has nothing working whatsoever now. Can't figure it out. Thanks!

Falcon2000

Unfortunately I doubt if this is going to help you with your problem.

My security system has a anti car jacking mode that would disable the engine's ignition and starter after a couple of minutes of run time if a code wasn't entered. Apparently the ignition portion of the system had a fault in it and it was at firstintemittently activating and then it completely failed. I had bought the truck used years ago and was never given any information on the system and was totatally unaware that it had the anti car jacking feature.After first finding that a whole section of the fuse panel had no power I had to start with the fusible link feeds from the battery, and thentracing thefeeds back through the harnesslooking forwhere the power was being interupted. I eventually ended up at the security system's black box buried way up under the dash.After I got the security system's discription and wiring diagrams on-line I was able to figure out what was going on and how to bypass the circuit.

Does your starter at least turn the engine over, or is it competely dead?