Hi people, wondering if anyone can give me some advice. I've got a 1.8t in my mk1 and all has been ok until I broke the 2 pin plug in the back of the alternator, wires were plugged into alternator but the pins were touching as the engine was running. So I replaced the plug and started the car up and the battery light is staying on and the battery is not charging. I've checked the blue exciter wire back to the fusebox and all ok. I tried unplugging the blue wire and started up the car and battery light remains on, I even plugged in a spare instrument cluster and still no joy. Does it seem like the connection being bridged has killed the regulator on the alternator? Hope someone has an answer for me. TIA
if light stays on even when alternator is unplugged, the blue wire is shorted to ground somewhere. need to chase it till you locate the problem
Yes, it stays on if the exciter is unplugged from the alternator, with ignition on and also with engine running. So I isolated the exciter from the spade terminal near the battery to the yellow plug (ce1 fusebox) and no short to ground, done the same from blue connector to instrument cluster and again no short. Took my 2 clusters over to crazyquiff today and they both checked out ok with regards to the battery light doing its job. Alternator has also been tested and ok. Now for the strange bit, I had carried out checks on my mates mk1 and his wiring is the same as mine in both yellow and blue connectors, I put the female exciter spade direct to battery + and his light turns off as intended, I try the same thing on mine and it started the front wiper motor?? Now it could be the fusebox, however it’s a NOS item and the car has yet to hit the road and is stored in a garage, so no water ingress. Do you think I should swap the fusebox first? Thanks
post a piccy of all of your relays, maybe one is incorrect. also, double check your G spades, one of them is hooked up to the battery charge wire circuit so if something is wrong there that would explain it https://clubgti.com/forums/index.php?threads/fusebox-faq.219775/
G5 is being used by the the 1.8t brown connector for ignition live, and G2 has the mk1 black spade connector going to it. The rest are free
hmm.check D/4, if the loom builder is like me he may have added the alternator wiring into the engine loom, I put the MK4 alt loom plug on so its nice and easy for my customers
I’m also using pin 4 & 5 from the P section on the fusebox for constant live for the 1.8t wiring. I done the loom myself following your guide, the exciter wire has been left as it was prior to me going from megasquirt over to Bosch me7.5
I’m not with the car until this afternoon, so will check d4, just incase I’ve inadvertently wired something into that spare pin.
thats fine, P are all permanent live common to each other very odd indeed. what about if you unplug the headlight loom entirely, does the light stay off?
I de-pinned the blue wire from the cluster, and now this is the only time the battery light has gone off. If I give that wire a 12volt feed, the front wipers activate, the same as when I give the exciter wire in the engine bay a 12volt feed. I’ve just swapped over the fusebox and exactly the same issue
ok, theres a big brown on the white engine loom plug make sure that is earthed to the white 4 way spade plug on the headlight loom. this should also have a wire from dash loom and another from rear loom to it. out the back is another brown with spade, that needs to go to the claw
Problem solved, thanks RJ. Luckily I had another loom, plug on the white loom was slightly damaged, the pin 12 was contacting 12 and 4. Replaced and all good
