Alternator Light On

[vwlover77]

This problem has developed over the past few weeks:

Early symptoms: Start bus, Alt + EGR lights sometimes stay on briefly (1 second) after the engine is running.

Recent symptoms: Start bus, Alt + EGR lights stay on until engine is revved above idle.

Sunday: Started bus, Alt + EGR lights stayed on until the engine was revved above idle. Drove for five hours at 65-70mph. Shut off engine, restarted, and Alt + EGR lights stayed on regarless of engine speed, although dimmed a little with higher engine speed.

I removed the cover of the voltage regulator to have a look. The wirewound resistor inside is burnt crispy with the internal windings showing, but the wires appear to be intact. Everything else (relay contacts, etc.) looks OK.

I replaced the voltage regulator, but the problem continues.

I have verified with a voltmeter that the system is not charging.

Alternator bad? If yes, rebuild or replace?

Inside the regulator:

[Amskeptic]

This problem has developed over the past few weeks:

The wirewound resistor inside is burnt crispy

I replaced the voltage regulator, but the problem continues.

Alternator bad?

I think. Blown diodes, for example?
Check wiring harness between the alternator and regulator as well, especially at tin holes.
Colin

[dingo]

Test for bad diodes...which put out an AC ripple

Take a digital meter and set it to AC mode. Select a voltage range to
read approximately 2 volts. Start engine and let idle. Negative lead to ground and
positive lead to BATT+ lead on the back of the alternator. You should have less than 0.1
volt AC.

[vwlover77]

I replaced the alternator with a Bosch rebuilt unit. That was fun, in a twisted way. The wiring was in good shape thanks to the rubber grommet.

Problem solved.

[glasseye]

Are the diodes part of the alternator assembly?

[vwlover77]

Yes, internal to the alternator.

[jcbrock]

That was fun, in a twisted way.

Shoot, I know people that do it by the side of the road near Nowhere, Montana.

[aopisa]

That was fun, in a twisted way.

Shoot, I know people that do it by the side of the road near Nowhere, Montana.

I would be found as a skeleton with its legs poking out from underneath a bus if I attempted the things that Colin does out in the wild .

He just helped me change out my alternator. No more glowing light.

Fortunately, we did not have to use the "Amskeptic Jaws of Death Pulley Mangler".

[Amskeptic]

That was fun, in a twisted way.

Shoot, I know people that do it by the side of the road near Nowhere, Montana.

I would be found as a skeleton with its legs poking out from underneath a bus if I attempted the things that Colin does out in the wild .

He just helped me change out my alternator. No more glowing light.

Fortunately, we did not have to use the "Amskeptic Jaws of Death Pulley Mangler".

Hey. You should know we also have the Florence Nightengale Tender Ministrations Pulley Visegrips N File Repair Kit to make the alternator pulley mostly straight-like and kind of not-too-wobbly almost sort-of.
Colin