Alternator Overcharging

[dac69er]

Hey Jay...we re in the mix trying to find out what the fault is. That pdf seems to be different to the wiring of my car...thats for a mk1 where as my car is a 1994 model. We have a thick white wire coming from the the main 50amp and 80amp fuses. Its showing as a earth/ground on the multimeter. Is this correct? My electrician is convinced that this is the problem as you should not have an earth going to a live fuse?

Thanks

Sounds like you may have a wire that has rubbed though and goes to ground causing your issue.

 

[Jay]

Sounds very much like it. Best option is to trace the wires back looking for any signs of scorch marks or heat in the looms. Double check any areas that past close to metal (bulkhead holes for example) in case it's as Duncan says and a wire has rubbed through on a sharp edge.

 

[Djaniero]

Its the bane of my life right now! It was strange how it happened. Turned on the car, the battery warning light came on and the alternator belt began to squeel slightly...then as I drove further....my wideband died....I turned on the lights then all the electrics died.

I'll have a hunt for any damaged wires and let you guys know.

 

[Djaniero]

Quick update guys.

Ended up taking the dash out today and having a proper look at all the wiring to see if we can find a fault. Then something interesting happened.

We removed the earth off the alternator, then the wires 2 fault wires stopped earthing. So now the electrician is convinced that the 2 earths connected to the alternator should not be going directly to the 80a fuse??

I tried to explain to him that, to my knowledge the wires have been always like this. But I have never seen any other Gt fuse boxes to compare it too.
Any thoughts on this?

 

[dac69er]

its been a while since i have removed a GT alternator, but i thought there was just the main power connection to the alternator and the plug connection, no separate ground?

you sure the wires arent the power wires that come from the alternator?

you are saying that with the wires disconnected the fault went? this would point to an alternator fault if everything was connected correctly in the first place.

 

[Djaniero]

I'll double check with the electrician again. Just just like you said, theres a plug connection on top of the alternator and 2 other wires that form as ring terminal that you then attach to the alternator.

But as soon as we disconnected it, the wires at the fuse box end (which we're certain are the same 2 wires) were no longer earthing.

If they are power wires, would they be going from the alternator to the main fuse Dunc?

 

[dac69er]

I'll double check with the electrician again. Just just like you said, theres a plug connection on top of the alternator and 2 other wires that form as ring terminal that you then attach to the alternator.

But as soon as we disconnected it, the wires at the fuse box end (which we're certain are the same 2 wires) were no longer earthing.

If they are power wires, would they be going from the alternator to the main fuse Dunc?

yup, they are the ones. if you are saying these were going to ground, then it sounds like you have a bad alternator if the wiring itself is ok.

 

[Djaniero]

So with a good working alternator, once these wires connected to the fuse, they no longer will be showing as earths? The electrician wasn't having any of it lol...He was like no....you can't send an earth to a fuse.

 

[Djaniero]

Sorry to Pester guys, but could I get an answer on this before I go and get my alternator reconditioned?

Thanks

 

[Jay]

I'll openly admit I'm pants with wiring but if you tell me what wires to check I'll try at the weekend.

 

[Djaniero]

I'm the exact same man....Havent got a clue when it comes to these things...hence the 101 questions lol.

I just need to know if the 2 white wires that come from the alternator, go to the main fuse in the engine bay.

Thanks Jay