R33 alternator replaced --> weird warning light

[savage1987]

I replaced the alternator on our R33 today because the battery light was coming on at idle.

I installed a Bosch item that was recommended as a replacement. It all fit OK, and it's a 14V 85A unit, compared with the (12V?)80A old one.

The warning light at idle was gone

Mrs drove it to work, it still starts and drives OK, but now whenever the car is OFF the batt warning light comes on, and remains on,


Any ideas??

Thanks,
Sam

[wamboin23]

bxn1231a i'm guessing?

never had a problem like that before, but sounds like possibly a dodgy regulator or diode. the warning light has ignition on one side, and a circuit to the reg on the other side. when the alternator is not charging, the regulator earths this circuit to bring on the warning light, and 12v when charging to turn out the light (12v on both side, no current flow).

what it sounds like is happening, is that when the ignition is off the warning light is getting an earth through other ignition components (radio, clock etc), and the regulator is for some reason giving the warning light power as if it is charging, which illuminates the light.

[savage1987]

BXN1231A indeed.

That thing is such a pain in the ass to change, I really need to get my hands on a multimeter and learn how to use the bloody thing, test as much as I can before pulling it out again

[wamboin23]

thats would be the best bet.

with ignition turned off, you should have power on only one wire going to the regulator. if there is power on both, well thats confirmation there is something wrong. disconnect the regulator plug, and if the light goes off, definatley alternator.

did you get it from a shop with warranty?

and make sure you disconnect the battery, don't wanna flatten the battery.

[savage1987]

Aaaaaaaaaand here's the awesome development that has me really hating the car


Forgot to disconnect battery last night, battery light was still on this morning

Jump started the car..


Didn't sound like it was too happy idling, I hopped in the driver's seat:

Speedo going all over the place, was at 100kph idling, I gave the throttle a tap and it jumped off the top of the scale
Stereo flickering on and off as though there's a short somewhere


that's all i noticed before I turned it off to hopefully avoid doing too much damage to stuff.


I have no idea how to even approach this, which is the really awesome thing.




In other news, when I unplug the 2pin on the back of the alternator (with the car off) the battery light goes away. Internal fault for sure??? What would have happened if SOMEHOW the little conversion plug they give you was wired backwards? At the moment it goes

[SKYLINE HARNESS-------BOSCH ALT]


light green-----------------------black
white----------------------------red


which I don't know but seems weird to me

[wamboin23]

which plug is on the alternator?

same as a 5litre alternator?
or same as LS1 alternator?

[savage1987]

Unsure but it looks like it's the same as an injector plug with its little spring clip thingy ... haven't seen a 5L one lately (thankfully)


Bosch's auto sparky want to have a look at the car on Tuesday, they seem happy it's a dodgy alternator (or at least regulator) and they will also fix any further damage the faulty alt has caused, if any.

[wamboin23]

yeah same as 5litre.

good outcome.

[savage1987]

well it seems the reason the reg is ####ed is because it was the wrong one. Amazing. Thanks very much Bosch

getting it back (repaired/replaced) tonight, will throw it in and hope the rest of the system is all ok.. otherwise off to the auto elec tomorrow for further warranty fixes.