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View Full Version : no alternator lamp.. possible problem?



fujioko
01-12-2007, 11:15 PM
My bimmer suffered an electrical malfunction last week. I was cruising along and I noticed the ABS lamp was on. Shortly thereafter all the gages went dead.

The car barely made it home. Latter that day I charged the battery and started the car up. My DVM indicates the battery is not getting a charge ~12.00 volts engine running. The voltage drops further when I turn on the headlights.

Sounds like an alternator problem, however there is NO generator/alternator lamp on the dashboard. Curious…so I shut off the engine and then switched the ignition back on without starting the engine. Still no idiot light for the alternator. Hmm. … I guess I never noticed the lamp before, so I don’t know where to look on the IPC. (instrument panel cluster).

Keep in mind this car has covered 281K miles. I guess its possible for the lamp in the IPC to finally fail.

As I recall, some alternators require the idiot lamp to function in order to complete the circuit for the regulator. I’m not sure it this is the case for BMW. It certainly was true for GM cars of the 70’s and 80’s.

Ok, here is the stupid question.. where on the IPC is the alternator lamp supposed to be?. Also, dose anyone know if the lamp is required for the alternator to work?

BTW the car is now in storage for the rest of the winter. I’ll miss it for now.

Morgenster
01-13-2007, 04:08 AM
Mine didn't give me any warning except that during driving my battery light was faintly glowing.
Looks like you're in for some alternator fixing or replacement.

Ross
01-13-2007, 04:16 AM
The warning lamp for the charging system is the battery symbol.Look below the fuel gauge, it's the one furthest left next to check engine.
The Bosch alternators can often be repaired by replacing the voltage regulator which includes the brushes. This is easy to do and saves a lot of $$.

Paul in NZ
01-13-2007, 05:24 AM
when you turn on the ign befre you start do you see a Battery symbol?

Barry
01-13-2007, 07:25 AM
My 535 had the problem of not charging..found the plug in the alternator harness from the engine to body was corroded badly..pulled the plug,cleaned up properly and its worked well ever since...
Sometimes not seeing the woods for the trees....

fujioko
01-13-2007, 08:29 AM
With the “key on”, (engine off) there is no battery symbol light. Hmmmm… something not quite right.

I just gave the Bentley a look and discovered the alternator lamp is in series with one of the unloader relays. Bentley indicates the lamp must function before continuing with the diagnostics on the charging system… I’ll give this circuit a good look over.

Anyway I fully intend to replace the regulator or brushes if that is all that is wrong. It could be a cheap and easy fix.

Something else.... I didn’t mention before, however it could be important. When the charging system was functioning, the headlamps would pulsate when the car was idling.
The car did this ever since I bought it. Perhaps one of the diodes has been bad? Is the diode rectifier assembly part of the regulator ?

632 Regal
01-13-2007, 08:57 AM
no it isn't, thats an internal alternator part but it can be replaced.
Is the diode rectifier assembly part of the regulator ?