Andy1

It occurred to me (unless I misssed something) that the PCM +12V signal wires are not fused. Take for example the fuel pump signal wire which sends +12V to the fuel pump relay. What happens should this wire short to ground? How are these circuits protected? Does the PCM have an internal circuit breaker?

Thanks,
Andy1

bczee

iTrader: (12)

I would fuse mostly everything that can cause a various load. Better to be safe than fry something.

Take a look at the Fuse box from where the donner came from and you can see which circuit are fused and go from there..

Coil, Injectors, Trans are a few others (Pink wires).

BC

gofastwclass

iTrader: (2)

Coming from the PCM to accessories nothing is fused however, power going to the PCM (+12 constant and ignition) is fused. If memory serves me correctly, the fuse for the fuel pump is on the constant power side, not the pump or PCM side.

I've never seen one fail so honestly I never put that much thought in it and duplicated what the factory did.

Pocket

iTrader: (22)

The PCM has two 12v constant inputs shared with the fuel pump relay battery line under a single fuse. It also has a single 12v IGN input shared with the MAF 12v IGN, also fused

The misc 12v, 5v outputs from the PCM are not fused. Taking one to ground (dead short) will only cause the PCM to code and disable the circuit. No circuits are at risk, so there is no reason to fuse

Andy1

Pocket,

Yeah, no one seems too concerned with the +12V PCM outputs. I frankly never thought about it before which was the reason for my question. So the PCM turns-off the shorted circuit?

Andy1