alterrnator & engine question

[Ronbo]

Gentlemen, I was driving home today and Gen 1 light just came on . It hasent had any issues , its starts fine etc . But Gen 1 lite stays on.. Cables are clean and tight , Your guess would be??? Alternator??
also I found someone with a used 6.2 running but knocking , is it worth $75 .00 ?
Thanks Guys for any help, I'm still working 2 jobs and cant have much down time... You are greatly appreciated !!!
Oh My vehicle is a 1986 1028....

 

[Matt65]

TM 9-2320-289-20 2-59

Check driver side alternator belt tension

6. GENERATOR LIGHT REMAINS ON OR TURNS ON DURING OPERATION (ALL EXCEPT M1010)​

Step 1. Check engine idle speed. (See paragraph 3-25)
Step 2. Disconnect connector from left alternator (if “GEN 1“ light is on) or right alternator (if
“GEN 2“ light is on). Turn key to “RUN” position.
If generator light is not on, trace circuit from alternator connector to generator
Iight in instrument panel. (See wiring diagram F-11) If circuit is good, replace
alternator. (See paragraph 4-2)
If generator light is on, trace circuit from alternator connector to generator light​

if instrument panel. (See wiring diagram F-9)

 

[Matt65]

Oh and for the $75 Running 6.2, I would buy it. Starter, Alternators, Injection Pump and a few other key parts would easily cover that.

 

[Ronbo]

Thanks Bro !!!!!
PS Matt I see you have a 4 inch lift , did you replece the front springs and use blocks in teh rear ? That is my next project ..and yes 37 humv tires ... ..

 

[Ronbo]

PS do you know if Gen 1 and 2 alternators are the same? also If I take them to a shop and have them rebuilt is there anything special they will need to know since it is a mil vehicle?

 

[Matt65]

No Problem. Exactly right on my lift. I ordered the parts from Off Road Design. The blocks in the rear were suitable for my needs, even though there are much better options for increased articulation. More lift information here: Link


Be sure to check back in and let us know how you fixed the GEN light. If the TM steps above lead you to replace the alt, have it tested at the parts store to confirm. If no good, You may want to look into an alt rebuild kit. This is probably what I will do when needed.

 

[Matt65]

PS do you know if Gen 1 and 2 alternators are the same? also If I take them to a shop and have them rebuilt is there anything special they will need to know since it is a mil vehicle?

No, they are different and this is an important point. The Passenger side Alternator MUST HAVE a isolated Ground. The Driver side does not.

 

[doghead]

No, they are different and this is an important point. The Passenger side Alternator MUST HAVE a isolated Ground. The Driver side does not.

Matt, that is a misleading/confusing statement. They are the same when built by GM and maintained by the Government.

They are identical. And they both have an isolated ground(but are not both used that way).

You can substitute a "readily available" alternator on the drivers side only, because in stock form it has a ground wire that essentially does the same thing as a standard case grounded alt.

They used the same alts for simple logistics.

The passenger side alt MUST be isolated ground.

 

[Ronbo]

Thanks for the info Guys.. I'll just take both to the alternator shop next week.. The shop works on just about every starter and alt. built.. I cant get the parts for what he rebuilds them for.... Thanks for teh help...

 

[Ronbo]

I just come in from checking the Gens. I cleaned all terminals, belts are tight..
I put a volts meter on gen 1 ( drivers side) and its putting out 31 volts, Gen2 27 volts. But at the batteries ( either one at Idle) I'm getting 12.7 ...
I did notice that as soon as the key is on that gen 1 lite comes on but not gen 2 .( key on before starting) is that normal?
I also was reading about dogheads starter relay and Think while I'm working on the truck I'll upgrade to the better relay. My relay and other Box thingys are just laying loose near the floor Not mounted.
also noticed a square box next to the relay that opens up and has some sorta curcuit board in it .. What is that????? Thanks

 

[1970amgeneral]

m35a2 alternator

hey guys. i have been trying to find some diagrams or info about the wiring on my deuce.. it didnt have an alternator when i bought it. i just bought one for it and dont have the wires. i can find the " wake up wire" on the truck but that is the only one. is there any way i can just run a wire to the starter and battery or is that a bad idea?? i would appreciate any help..

 

[85CUCVtom]

I would pay $75 for a knocking 6.2L. That kind of stuff is good to have hanging around. You never know when your gonna need something off it.