My Vette has been down for a year due to a starting circuit problem. Keep in mind I am in grad school so I don't have as much time to wrench on it as I'd like, but after some troubleshooting here is what I can come up with.

You can turn power on with the key, all of the accessories work, and when you turn the key to the start position you get the correct current interrupt (interior lights and radio will go out) but the starter solenoid does not attempt to engage. No click, nothing.

Battery is good. The starter is a new Powermaster starter. That was the first thing I replaced and if you take the starter off the car it works by jumping it. The starter gets power from the positive lead. The ground strap from the engine and the small one to the starter bolt are both secure and in place. I tried running a jumper wire from the positive battery terminal to the solenoid post to see if I could hotwire it. Still nothing. This leads me to believe that there is a grounding fault somewhere in the starter relay under the dash, and I have a new one on the way. Any other ideas what could be going on here? I'm at wit's end with it and my next plan is to just rip all the wiring out from behind the dash and point to point wire only the parts that I need. I don't run A/C, the rear defroster, the courtesy lights, etc.

 

The circuit is really simple- you state you have normal power when you turn the key on, but nothing when you turn it to start. Examine what happens when you turn to start- power thru the ignition switch goes to the purple 10ga wire, then to the neutral safety switch/ Automatic trans, that switch is mounted in the console on the shift lever. Contacts in that switch are closed in Park and Neutral, so power is run to the small start terminal on the starter.
1980, IIRC there is a starter extension harness on the firewall just to the right of the distributor- that plug has been known to melt- it's rectangular and has 6 wires in it.

 

when you replaced the starter did you properly mark the wires going to the starter solenoid and did not reverse them?

 

This is the second starter that's done this. The first (which worked before this problem) was wired re same way. I had one of my buddies who has built a couple Chevy engines check it and he said it's wired correctly. He wasn't familiar with the Corvette chassis wiring though.

 

Does your 1980 have a theft deterrent system in it like my 81 does? That could be giving you issues.......

 

There is also a Neutral Start Switch which must make connection before power is sent to the ignition system.

Did the new starter come with a new starter solenoid? Starter power signal is sent to the solenoid. When that solenoid kicks in, it sends power to the starter. Use a voltmeter to determine if the starter is actually receiving 12vdc when you turn the key to START. (measure between ground and that jumper between the solenoid and starter)

 

Thanks for the help so far guys. I'm not sure about the anti theft system. Originally I'm pretty certain the cat did have it as I think I was standard by the 80 model year. It should be keyed to the door lock but I've always left the doors unlocked and used a steering wheel immobilizer to secure the car (passenger door lock is broken since day 1 and it's been low on the priority list).

The powermaster starter came with a new solenoid. I always replace them together. I did some reading a few weeks ago and found out about the neutral switch but would that still function if I'm directly hotwiring the solenoid from the battery? That's what I don't get. If the starter is in the car, I can directly run a jumper wire from the positive terminal to the starter solenoid post and it won't go. Take the starter off the car, power it and ground it and then jump it and it works.

 

Check your wiring on the starter - engage signal wire goes to the inner terminal towards the block. Put it on the outer terminal and you get exact symptoms you are having.

 

Had the same issue - power on acc but no start. Traced all seatbelt and neutral safety switches - nothing. Turned out the ignition switch on the top of the steering column needed adjusted. There are 2 screws you can loosen, pull the switch toward the steering wheel, and then the "throw" on the switch makes proper contact. It wears out over the years.

 

Hey guys. Sorry to necro my old thread but I'm just now getting around to replacing the switch. While I was disassembling the steering column mounts I found a relay that had become disconnected under the dash. It is right near the fuse block, just to the left of it, and it is a black box about 2" x 2". There is a 2 prong spade connector and the connection that obviously goes to it has an orange wire and a green wire. Any idea what this is? I can't find reference to it in any fuse block diagrams. Thanks!

 

I have tried jumping the css to no avail i currently have it disconnected with alligator clips and a lead jumping the posts of the connector. As to the start relay my Test light shows (-) on pins 30, 85, and 86 no reading (+) or (-) and 87a is unused. As to the yellow wire leaving the ignition switch i found no (-) on said wire with any ignition position. unsure of where to turn.

In relation to the fuse-able links there are a few in my car that have some sort of rubber barrel on them one being about 8 inches away from the connection of the smaller gauge wire on the motor side of the starter along with the large direct from battery wire. is this barrel a feature so that when the fuse-able link gives in it shorts inside of that rubber barrel or does it serve some other purpose. to test the fuse-able link can i run continuity from the connector ring to a pierce probe on the other side of the barrel?
!990 corvette l98tpi zf6 transmission

 

You may want to start your own thread on this since this thread and the last post was 5 years ago. Jus sayin'.