1999 VR4 Galant ECU fuse keeps blowing

[jjw001]

Okay, so I've got a car that blows the ecu fuse as soon as the key is turned. I've followed the wiring from the fuse box to the ecu, no evidence of shorting. I then thought there was a few things I should replace anyway and replaced the fuel pump plus related relays, the cam crank angle sensors, pulled the ecu and took to a tech head friend who said there's no evidence of damage to the ecu. After all of this it's still doing the same thing so I'm about to pull the ignition and trace the wires back in a search for a short. Has anyone else gone through this with their own Galant/Legnum and can suggest something else to look at? First of all it was just a fuse that blew on the way to work which went for another 7-9k's after the fuse was replaced. Since then it goes as soon as you turn the key to start. Any suggestions would be appreciated (keep in mind my auto electrician abilities lie somewhere between almost completely useless and almost acceptable). Cheers, Jamie

[GalantOnly]

You must be more specific about what fuse is blowing. There are two fuses, that feeds engine ECU...

[jjw001]

Sorry didn't realise there were two (I haven't got any diagrams). The fuse is in the fuse box under the bonnet no.13 20amp with a picture of an engine. Like I said, I could know a lot more than I do!

[Nick Mann]

Alex is the electrical guru on our cars. Hopefully he can offer some advice. I'd suggest that it sounds exactly like a wire shorting on something. Often the first thing to consider is anything after market, radio, ebc, turbo timer, alarm, gauges etc.

[jjw001]

The head unit is about the only non stock electronic part on the car. I was thinking I'd have to go through the wiring to find a short but thought I should ask if there was something I hadn't thought of yet. Thank for your reply! Cheers,
Jamie

[GalantOnly]

This fuse feeds almost everything inside the engine bay...
Red wire goes to: engine control relay, engine ECU, TCL solenoids, injectors, idle stepper motor, cam- and crank shaft sensors, lambda sensor, MAF, boost and fuel pressure solenoids.
White/black wire to: A/T relay, A/T ECU and A/T solenoids...
So first take a multimeter and check for continuity between chassis and red wire and then chassis and white/black wire. So you know if it's engine ECU circuit, or A/T ECU circuit that shorts...

[GalantOnly]

But if the car is really 100% stock, look around engine bay for wires, that lost it's isolation because of the age and heat. The plast become glass-like because of enormous temperatures under VR-4 hood...

[jjw001]

I've got it all back together after finding an earth had dislodged (still no evidence of a short anywhere). I turn the ignition on and the fuse doesn't blow now.......but, now the engine just turns over and doesn't fire. I've checked fuel but need to check spark when someone is gets home. Anything I can check before then?

[jjw001]

No spark! I may have to pull the engine covers off again and see if I installed the cam and crank angle sensors properly (read something about the sensors clicking into place which I can't recall happening).