amc91z

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!

amc91z

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!

amc91z

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

Rockguy

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

deadbird

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

amc91z

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!

amc91z

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