Alternator Wiring burnt up. I need so help

Does it have spark? And other questions...

Moderators: Greenleaf, BC847, Richie O

Alternator Wiring burnt up. I need so help

Postby Collers9640 » Mon Feb 12, 2018 5:36 pm

I was coming back from lunch today and all the sudden The ammeter started to peg then about a minute passed and smoke filled my gauges, so I pulled over and turned off the truck.
Before I start my with what happened does anyone know what would cause amps from the alternator to jump up and stay high enough to burn up the wire harness?
(My truck is a 77’ Power Wagon cummins Conversion)
I popped the hood and checked the alternator wiring. The black charging wire that runs through the bulkhead connector to the ammeter was burnt up as well as the green wire that runs to the voltage regulator. However the red wire that runs that also runs to the voltage regulator Looked fine.
I continued looking around and the the red wire that comes from the ammeter and connects to the starter relay was burnt up very very badly and oddly the fusible link didn’t blow. Next I pulled the cluster and saw that the black wire that comes from the alternator to the ammeter was burnt and the red wire that goes from the ammeter to the starter relay had shorted to the black (that explains the smoke) but what cause it the heat up in the first place?.
What would cause the amperage to shoot up and stay there?
77’ W200 Cummins- Auto, BHAF, 4” Exhaust
91.5 W250 Cummins Conversion- PS I/C, pump maxed, Red Oak Diesel Injectors, Coolertubz, pump advanced 1/8", 3" elbow, 3200 Spring, Piston Lift Pump, KDP fixed, DennyT pin, HX35, 4in Downpipe, BHAF, Heater Grid Delete, Alcan springs, Bilstein Shocks
1984 D350 Crew Cab (Future Cummins Project)
Collers9640
fuel screw!!!!
 
Posts: 159
Joined: Wed Feb 24, 2010 4:25 pm
Location: Charleston SC

Re: Alternator Wiring burnt up. I need so help

Postby BC847 » Mon Feb 12, 2018 8:48 pm

What you describe is a dead-short to ground.

Look for evidence of a hot (12vdc) conductor shorting to the metal of the truck. Trace all the burn't wires to where the burn stops. Then look hard there. Most likely downstream of the ammeter.
David

1993 12mm VE Fueled W250 CC, Green
12.67 @ 103.35
Your basic farm truck ;)
BC847
Administrator
 
Posts: 1973
Joined: Wed Jan 03, 2007 5:22 pm

Re: Alternator Wiring burnt up. I need so help

Postby Collers9640 » Fri Apr 13, 2018 1:20 pm

The charger wire coming from my alternator burnt up my dash and engine harness about a month ago. So I pulled my Dash Harness and Engine Harness and rebuilt them. I also bypassed the ammeter in the Dash by following the instructions on http://www.madelectrical.com/electrical ... uges.shtml .
Everything was fine for about a week and a half then it burnt up again. So this time I used a 6 awg wire and flipped the the field wires on the alternator (the ones coming from the Voltage Regulator) and it burnt up in about 5 minutes.
I can’t see it being anything but a direct short to ground but its its odd like the short is intermittent.

Today I pulled the plunger out of the EFS so that I can keep the motor and be able to isolate different parts of the electrical system. I post what I find if anything. Also if anyone has any guidance on possible culprits it would be greatly appreciated.
77’ W200 Cummins- Auto, BHAF, 4” Exhaust
91.5 W250 Cummins Conversion- PS I/C, pump maxed, Red Oak Diesel Injectors, Coolertubz, pump advanced 1/8", 3" elbow, 3200 Spring, Piston Lift Pump, KDP fixed, DennyT pin, HX35, 4in Downpipe, BHAF, Heater Grid Delete, Alcan springs, Bilstein Shocks
1984 D350 Crew Cab (Future Cummins Project)
Collers9640
fuel screw!!!!
 
Posts: 159
Joined: Wed Feb 24, 2010 4:25 pm
Location: Charleston SC
Top

Re: Alternator Wiring burnt up. I need so help

Postby Collers9640 » Sat May 26, 2018 7:57 pm

Just to let everyone know it turned out to be the alternator itself. I don’t know how but the fields on the alternator would randomly max out to 35+ volts and hold there. Freaking weird.
So after rebuilding my Dash Harness & some of my engine bay harness
Replacing voltage regulator with a high dollar one and the starter relay and the battery it turn out to be the dam alternator. EVEN THOUGHT THE ALTERNATOR CHECKED GOOD!!!
77’ W200 Cummins- Auto, BHAF, 4” Exhaust
91.5 W250 Cummins Conversion- PS I/C, pump maxed, Red Oak Diesel Injectors, Coolertubz, pump advanced 1/8", 3" elbow, 3200 Spring, Piston Lift Pump, KDP fixed, DennyT pin, HX35, 4in Downpipe, BHAF, Heater Grid Delete, Alcan springs, Bilstein Shocks
1984 D350 Crew Cab (Future Cummins Project)
Collers9640
fuel screw!!!!
 
Posts: 159
Joined: Wed Feb 24, 2010 4:25 pm
Location: Charleston SC
Top


Return to Electrical

Who is online

Users browsing this forum: No registered users and 4 guests

cron