Ignition dead short :(

[Humby]

Hi,

I have two Hummers I am doing some major work on. We unplugged the wiring loom and took out the dash and all units and steering wheel. Just as a test, to turn the engine over (BEFORE we did any work on the car at all) we put back all the stuff.

Now, the 40 amp fuse on the main ignition under the hood blows as soon as you try and start the car. Basically it is shorting direct to Earth. This is on both our cars.

Other than disconnect the plugs on the loom and take out the wheel we aint done nothing. Honest!!

Any ideas what we did wrong? We have spent a week on this with a meter getting nowhere.

[Humby]

Hi,

I have two Hummers I am doing some major work on. We unplugged the wiring loom and took out the dash and all units and steering wheel. Just as a test, to turn the engine over (BEFORE we did any work on the car at all) we put back all the stuff.

Now, the 40 amp fuse on the main ignition under the hood blows as soon as you try and start the car. Basically it is shorting direct to Earth. This is on both our cars.

Other than disconnect the plugs on the loom and take out the wheel we aint done nothing. Honest!!

Any ideas what we did wrong? We have spent a week on this with a meter getting nowhere.

[Humby]

Hi,

I have two Hummers I am doing some major work on. We unplugged the wiring loom and took out the dash and all units and steering wheel. Just as a test, to turn the engine over (BEFORE we did any work on the car at all) we put back all the stuff.

Now, the 40 amp fuse on the main ignition under the hood blows as soon as you try and start the car. Basically it is shorting direct to Earth. This is on both our cars.

Other than disconnect the plugs on the loom and take out the wheel we aint done nothing. Honest!!

Any ideas what we did wrong? We have spent a week on this with a meter getting nowhere.

[Klaus]

You must have done something!

You said you did "major work" on them. What exactly did you do?

[PARAGON]

I think some more details are needed. You did say that you have plugged everything back up and it's blowing the fuse?

Is blowing the fuse when you turn the key to on or is only when you attempt to crank?

Did you remove or change anything under the hood?

I am no mechanic or expert or anything but I think you have done something that is affecting the Hummer's Class 2 databus system. I think I remember somewhere that the databus system is short circuit protected to ground which is probably why you are blowing the ignition fuse.

[DRTYFN]

Humby,
You must be a Jaguar mechanic.

[Klaus]

Come to think of it... I wonder if they installed any Lucas electrical equipment on it!

That would explain it!


"Lucas - The Prince Of Darkness"

Why do brits drink beer warm? Because Lucas makes refrigerators too!

[PARAGON]

You might be on to something Klaus, being from the UK maybe Humby picked up a harness made by Lucas, after all he is known as the inventor of the short circuit.

[Hummie2]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> Now, the 40 amp fuse on the main ignition under the hood blows as soon as you try and start the car. <HR></BLOCKQUOTE>

Which 40A IGN fuse blows, IGN A or IGN B?

[Humby]

I solved the problem.

I rewired the entire car after a major re-build. Two of the plugs were identical and I did not have the original wiring diagram, so... bang.

Sorted now though, thanks for all the helpful replies.