HELLO, THE OTHER DAY I COULDN'T START MY 142s. SINCE THE BATTERY AND THE ALTERNATOR(REPLACED FROM GENERATOR TO ALTERNATOR SYSTEM) WERE OLD,I BOUGHT A NEW BATTERY AND HAD THE ALTERNATOR REBUILT. THE CAR STARTED UP FINE, BUT THE AMP LIGHT ON THE DASH REMAINED ON.I TOOK THE ALTERNATOR AND THE VOLTAGE REGULATOR BACK TO THE GENERATOR SHOP AND THE OWNER TESTED THEM BOTH AND SAID THEY WERE GOOD. REINSTALLED THE ALTERNATOR AND VOLTAGE REGULATOR, BUT THE AMP LIGHT REMAINS ON.COULD THE VOLTAGE REGULATOR BE BAD? THANK YOU. STEVE.

What type of alternator, Bosch, SEV or some other retrofit?

If you have a voltmeter, measure the voltage on the battery with the car running. If it is 12 volts or lower, the alternator or regulator (or something) is inoperative. If the voltage is more like 13 - 13.2 volts, then the alternator and regulator are working and the problem is with the connection of the alternator sensing light. However, if the alternator light is incorrectly connected, the alternator typically will not operate (it needs the trickle current through the alternator light filament to flash the alternator field).

The wiring for a SEV or Bosch alternator is:

Df connection on external regulator (normally the green wire on OEM installations) connects to Df connection on alternator.
D+ connection on external regulator (red wire on OEM) connects to 61/D+ terminal on alternator.
D- connection on external regulator connects to good ground.
Wire from charging light connects to 61/D+ terminal on alternator.
The big B+ terminal on the alternator is connected to the battery + terminal.

it's a bosch alternator. i don't have a volt meter to test with. i've already made sure that all connections were cleaned including the amp sensor light connection off the alternator. with the amp light on, i drove the car about 2 miles. i noticed that the turn signals seem to run a little slower than normal.

Looks like you are getting a new regulator. There is a good chance that is the problem if all the wiring is correct. If you had a voltmeter, there is a way to test and adjust the existing Bosch regulator; but, without a voltmeter you are SOL.

If the regulator does not fix the problem, then the next obvious candidate would be to check the field winding resistance; however, you need a multimeter tester to do that and if the alternator was rebuilt, the field winding and brushes should not be a problem.

Thank you for your advice.

I put a new Buco voltage regulator But the amp lite still went on. Took the car back to the generator shop and they tested the alternator. They replaced the diode/diodes and the the amp lite remains off and everything is good.

Its very unusual for the diodes to fail, unless it was a bad connection, or there was a short circuit that resulted in overheating of the diodes.

I thought way back at the start when the charge light was on that you took the alternator back to the repair shop and they said that the alternator was working fine?

Can you supply pictures of both the back of the alternator and of the voltage regulator focusing on the wiring?

FYI, SOME PEOPLE CONSIDER TYPING IN ALL UPPER CASE AS RUDE AND AKIN TO YELLING.

I don't really care either way, but still post pictures, IF YOU WANT!! :-) :-)
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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502

Hope you got the images.

I got the pictures.

Since you don't have a voltmeter, it will be difficult to diagnose the problem.

However, I think your voltage regulator is bad and I don't particularly like that brand of voltage regulator.

I prefer the Bosch electronic voltage regulators, but they are expensive, so I also sell and recommend the Beru brand which is a copy of the Bosch and they are a lot cheaper.

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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com

Eric, how much is shipping on the "Beru voltage regulator?" My area code is 95035. Thank you.

$7.50 for USPS Priority Mail.
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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502

thanks eric.