Weird electrical issue 4th gen BB1-FIXED

Post by **vanzep** » Fri Mar 10, 2023 3:47 pm

Bit of a weird electrical issue with my BB1 so thought i would post up and see if anyone has had similar issue.

Problem/symptoms:

dimming dash and intermittent warnings lights coming on. car not starting - clicking sounds just like nearly dead battery.brand new battery just fitted.
today i went to reset the idle as it is sitting at 1100rpm - followed the procedure in the manual but when i unplugged iacv car would not start - when i plugged iacv back in car started. then got dimming dash, flickering warning lights and speedo went dead after about 5mins of driving - car still drove fine. When i parked up all electrical items such as sunroof and winding windows up all very slow.....

My thoughts/possible problem areas:

distributor fault but car runs fine
ecu fault but nothing on dash and no stored codes
icm fault
wiring fault
alternator fault
main relay fault

I am not very good with electrical issues and all i can think to do is start blindly swapping parts out.
So any suggestions welcome.

arif_manji · Post by **arif_manji** » Sun Mar 12, 2023 1:31 pm

vanzep wrote: ↑
Fri Mar 10, 2023 3:47 pm
Bit of a weird electrical issue with my BB1 so thought i would post up and see if anyone has had similar issue.

Problem/symptoms:

dimming dash and intermittent warnings lights coming on. car not starting - clicking sounds just like nearly dead battery.brand new battery just fitted.
today i went to reset the idle as it is sitting at 1100rpm - followed the procedure in the manual but when i unplugged iacv car would not start - when i plugged iacv back in car started. then got dimming dash, flickering warning lights and speedo went dead after about 5mins of driving - car still drove fine. When i parked up all electrical items such as sunroof and winding windows up all very slow.....

My thoughts/possible problem areas:

distributor fault but car runs fine
ecu fault but nothing on dash and no stored codes
icm fault
wiring fault
alternator fault
main relay fault

I am not very good with electrical issues and all i can think to do is start blindly swapping parts out.
So any suggestions welcome.

@vanzep I would start with the alternator first mate.

Scott560 · Post by **Scott560** » Sun Mar 12, 2023 1:56 pm

Most likely to be the alternator, but before swapping it out do a good physical check of the main components.

That is, check the earth cables are not fractured within their insulators, check they are making good contact. Especially the one on the slam panel.

Check the fusebox similarly, reseat the fuses and check the fat ones to see if they are cracked or show any burning/hotspots.

Also, check the voltage. At the battery terminals it should be over 12.5v when resting (leave it a bit after running before measuring). And over 14v when the engine is running. Check the voltage at the alternator main stud (under the rubber protector), the battery positive terminal, and at the fusebox junction. Check it whilst the car is running. If the voltages are differing massively whilst the car is running, then you probably have a bad cable between alt/battery/fusebox.

Slow running windows sounds like a flattening battery, most likely caused by failure to charge, which could either be alternator or associated wiring.

Also check the main earth strap/wire to the gearbox, this is where the alternator earths mostly to.

Post by **vanzep** » Sun Mar 12, 2023 5:49 pm

thanks for the suggestions

it does remind me of previous alternator issue - was a bad connection at the main stud

Post by **Drax** » Mon Mar 13, 2023 8:52 am

i agree, similar to an issue i had on the 4g where the cable end connecting onto the alternator broke

Post by **vanzep** » Tue Mar 14, 2023 5:31 pm

Yes it was the alternator - so swapped in an old one that i had spare and all is good.

There wasnt a connection issue at the binding post contact just seems it stopped working so guessing it was the rectifier that failed.

Andyjess666 · Post by **Andyjess666** » Tue Mar 14, 2023 7:58 pm

You could get that reconditioned then you have basically a new one just in case don't cost alot either

Post by **vanzep** » Tue Mar 14, 2023 11:46 pm

do you have a link to where i can get it reconditioned

Post by **Drax** » Wed Mar 15, 2023 10:47 am

viewtopic.php?f=4&t=31417
knowing your skillZ you can source the parts yourself and rebuilt it

Andyjess666 · Post by **Andyjess666** » Wed Mar 15, 2023 1:28 pm

There be somewhere near where you live that will do it in Edinburgh or Glasgow mate just have to Google it