So I just picked up a 1990 Iroc. The body harness behind the dash was fried when I got the car. I pulled all of the interior out and replaced the dash harness with the one from a 1991 z28 I had years ago. I retained the original VATs module, ECM, etc from the iroc. The car is still all apart, aside from the dash and wiring. No accessories plugged in. The first problem I am having is that it will not crank over. I have checked the key and set up some resistors to match the keys and installed them just in case it was a VATs problem. Still nothing. The purple wire to the starter is not sending any power to the started. When I checked the purple wire, it is acting as a ground when i use a multimeter. No fuel pump is coming on, but when I check the gray wire to the pump, it sends power to the pump for a couple of seconds when the key is turned on. The car has sat many years, so I assume the pump is bad. It will also pop the acc fuse when i plug in a connector near the ECM. The acc wire in that harness looks to go to the ALDL port. I really am at a loss here and very frustrated. The harness I put in came out of a 91 z28 that I drove for many years and never had a problem with it. I only pulled it out when I did an LS1 swap. Is there any difference the way the 1990 and the 1991 harness may have been pinned at the bulkhead or anything? Any input is greatly appreciated!

 

I also forgot to mention that I have replaced the ignition switch above the column. It has 12v in and 12v out to the starter relay when the instrument cluster is out of the car. Once I put the cluster in, it still has 12v in, but only 6 volts out to the starter relay...
Thanks!

 

The car will also crank over when I jump the big positive and the purple wire on the starter with a screw driver....anyone???

 

Obviously you need to fix the 6 volts out to the starter before you are going to get anywhere. Did you try jumping 12v to the purple wire at the ign switch? Every diagram I see has a yellow wire for the starter but, since this car isn't stock, it's hard to go by that I guess.

The popping ACC fuse, there has to be a short in that harness somewhere. Shorts aren't always fun to find. Take a good look at the connectors. Make sure they aren't shorted somehow. Then you just have to follow the wires. There are tools that are supposed to help. I have never used any of them though. Here is one interesting example. http://realfixesrealfast.com/realfix...it_Tester.html

 

Including key? The resistance value to vats has to be from the original key, not your current one.

 

I haven't had time to mess with it in a few days, but I think there is a short in the purple wire, between the neutral safety switch and the bulk head connector. I will try and get back to the shop tomorrow and try and ohm the wire and see what I come up with.




I kept the original pass key box behind the dash with the car as well as the original column and key.



Thank you guys for the input so far!

 

Ok, I found the small (purple wire) to the starter was grounded somewhere in the engine bay. Spliced in a new wire from the bulkhead connector to the starter and it cranks over now (with starter enable relay bypassed). I just replaced the fuel pump in the tank and its getting fuel up to the rails but the injectors are showing no fire with a noid light plugged in. Does the VATS disable the fuel pump too, or just the injectors?
Thanks,
Adam