Im having a problem that's been driving me nuts for 4 years now. I got a 90 camaro with the 3.1 in it as an every day driver/road trip car. When the original engine started getting weak, I pulled a 3.1 out of a 92 camaro and threw some new rings on it, and rebuilt it and put it back together, then put it in the 90. Right away I started having weird problems. When the cooling fan, or the blower motor was turned on, the car would completely flat-line and die.

What I thought had happened was there must be a part in the wireing harness that was causing problems, maybe a stretchered cable or something causing a short. Well I wanted to visually inspect the entire wireing harness anyways and repair other bad spots in the harness so I gutted the whole car and checked the whole harness, but I did NOT find any obvious problems with it that would cause such a bad short.

I got reason to believe now that the donor car had the problem before I swapped the engines. So Im wondering if it is a sensor/cooling switch problem. I don't have the original 90 engine anymore, so im not sure where the 90's sensor/switches should be located. I'm not even sure they would be different between the 90, and the 92 but there is obviously some issue going on here. Anyone got any ideas on this?

P.S. The new 3.1 runs spectacular, but it does eventually kill the engine computers...