Alternator Wiring Question

[jeremiahm]

Hello all, first non-intro post. I have been crawling the site and google in general for this answer. I have a 1990 suburban with TBI. I have the serpentine belt system. My main battery is draining overnight. It was fine, then just started draining. Have not had time to chase wires yet, but I think my wiring on my alternator may be a bit "fuzzy". Here is what I have and can anyone tell me if it is correct to stock:

1. Wire from battery to big lug on alternator.
2. 3 Wire harness from loom:
-2 small wires to plug
-1 large wire to big lug

I think this is a 3 wire alternator and cannot figure out why or if the second wire to the big lug is there. If i disconnect it the truck wont start, same if i disconnect the battery lead.

Thanks all, Jeremiah

 

[4xcrazy]

Get the battery tested. A lot of times when they won't start the next morning is due to a bad cell.

 

[ktmoutfront]

^^^This. Then let us know what y8u find. If it is good, hit me up. I am in Falcon. You could run it out here and we could start testing.

 

[MrSchaeferPants]

Get the battery tested. A lot of times when they won't start the next morning is due to a bad cell.

Just happened to me yesterday. Been noticing crank-lug-crank-fire up for a few weeks, attributed that to not driving it often. Went on a 4 hour road trip three days ago figure it'd get the battery fully charged up and the engine good and hot.

Started it up yesterday morning, went to the store, got back. Few hours later it was just straight DEAD. And I didn't leave anything on. Looked at the sticker 5/10, so 5 years old, its probably toast.

 

[diesel4me]

I'd recharge the battery and put a test lamp between the positive cable and the positive battery terminal--if it lights up,something is drawing current,and will drain and kill the battery...this could be due to a short circuit in the wiring,a bad diode in the altenator,etc...it'll kill the new battery if you dont make sure there is no draw on the battery this way..

 

[jeremiahm]

I have tested the diodes on the alternator and they are good. Batterty was tested a few weeks ago when this started. I have a dual battery setup with a solenoid between them. i can always light up the solenoid and have and jump myself. i did have to replace the first battery and i moved this one into the stater spot. it tested perfect as it has had an easy life as a second battery.

My main concern is that the alternator is wired wrong. can anyone tell me how theres is wired? I would appreciate it.

KTMOUTFRONT I may take you up on that offer! thanks.

Jeremiah

 

[jeremiahm]

Hello all, i figured it out. I was my headlight switch. Started doing crazy stuff like turning the radio on and off with the dimmer function! I think it is the dimmer circuit. Pulled the tail light fuse and she stays charged all night.