Voltage Regulator - 2004 Marquis Garnet - CAT C12

[Rick Vyncke]

Both dash gauge and Aladdin indicate alternator is charging at over 18volts.  Prior to that happening, the volt meter would bounce between 13 and 15 volts and dash and headlights would dim and brighten in cadence with the volt gauge.

Probably safe to assume the voltage regulator has failed.  Where is it located?   Is it inside of the alternator or is it separate?  If inside of the alternator, does anybody have specifications for it… make, model, amps?

Aladdin indicated it was putting out just under 190 amps when it was charging at 18 volts.

Thanks

[Richard Davis]

Rick
I "assume" you have the standard Leece/Neville alternator.  The voltage regulator is screwed down as a top plate on the alternator.  You can replace it yourself but it is a little tricky to get the springs and carbon brushes back in place.  (You have to depress the brushes on the springs and hold them down with small diameter wire through holes in the alternator below the regulator.  And you have to be very careful that the two wires go into the slots when you screw the regulator back down.)  I replaced the regulator on mine first, but the diodes failed in the alternator a few months later (they may have been failing earlier that caused the regulator to fail).  I took the alternator off and took it to a rebuilder.  You may want to do it that way and be done with it at once.  DO NOT take a rebuilders off-the-shelf unit in place of your original.  Have yours rebuilt.  There have been many horror stories about replacement units not really being compatible.  (Search the Forum for DUVAC.)  Good luck.
Richard   

[Bill Lampkin]

Voltage is controlled by the alternator. 190a at 18v is way too much!, When my alt failed last year, it failed low. that is, it wasn't putting out enough juice. If you are in the Eugene Or area, this shop will have the right alternator. JNS Alternator and Starter.
My alt was a Leece-Neville alt that has a voltage sense lead, (12 ga wire). If yours has this sends lead, make sure to replace with a like alternator, don't try to shove in a Alt from a Chevy or Ford (or whatever).

[Rick Vyncke]

If anybody knows of a reputable company that rebuilds alternators in or around Colorado Springs or Denver…. Please let me know

Want original equipment… not some cheep replacement.  If I can have it rebuilt…

Thanks

[David T. Richelderfer]

This firm gets great reviews, 61 reviews.

Speedometer and Alternator Service Co. Inc.
449 E Kiowa St
Colorado Springs, CO

719-632-3165

[Rick Vyncke]

Thank you Dave!

[Rick Vyncke]

Speedometer and Alternator Service Co. Inc. in Colorado Springs stopped servicing/rebuilding alternators in August 2021. 

I did find Quality Alternator in Colorado Springs who can rebuild Leece Neville alternators....

Thanks Much!