Electrical issues
 

I'm transplanting an engine from one car to another identical car. A shop wired it up for me so as best as I can assume the wiring was alright for them, and I or a previous person have wired poorly somewhere.


When the ignition on the car is turned on, the body/ground starts to read a slight voltage, which i assume should really be reading 0.0v? It used to be around 0.1v when I first noticed, now it's reading around 0.02v.

I kept the engine loom on the engine, and have replicated their wiring at the fuse box (and alternator/starter). It's difficult to pinpoint what could be wrong, most of the wiring seems to make sense. The positive battery terminal, starter/alt feed and fuse feeds all interconnect. Negative terminal just grounds to the engine and body. There's only 3 or 4 other wires on that loom which are modified.

I've cut all the stereo wiring so it can't be that. Immobilizer is a possibility. I haven't modified any other wiring inside the car.

Any ideas on what could cause these situations?