Alternator and battery light

Post by **CycloneMike** » 30 May 2008, 18:33

This is nothing to do with my van, but I'm having a few problems with my other toy car.
Can anyone tell me how the battery charge light output on the alternator should work.
Am I right in thinking that it is earthed when the alternator is not spinning/charging, then switches to open circuit when spinning/charging or should it go live when charging??
Help please!!

Mike.

Post by **bigherb** » 30 May 2008, 18:56

Depends on what car some work through the engine ECU.

Post by **CycloneMike** » 30 May 2008, 19:22

No mate this has nothing to do with the ECU.
Its a basic old Bosch alternator which came off a Cavalier GSI, but its now in a kit car.
Its got two connections one for power and one for the charge light.
It switches from earth to live when running which is causing a back feed through the dash PCB which is keeping the engine running when the ignition is switched off. I expected it to switch from earth to open circuit but must be wrong.

Post by **bigherb** » 30 May 2008, 19:50

In that case it's working correctly. How have you wired the battery warning lamp.

Post by **CycloneMike** » 30 May 2008, 20:21

The light is part of the dash binacle. It's +ve fed via the PCB from the switched ignition feed and earths out at the alternator. It switches on and off as it should, only it caused other problems. Just need a rethink with the supply or put a switch relay in it. For some reason I got it in my head that the alternator would switch from earth to open circuit not to a live feed.
Cheers.

Post by **bigherb** » 30 May 2008, 20:34

Yes that's the way it should be wired.