charging problems

[meenkeene518]

Hello all,

Ive done some searching on the boards to find an answer but it inst exactly the info i was looking for, so ill see if it can be answered. I have an 86GN with the LT1 alternator on it, and with all the stuff running ( a/c, fan on high, lights i get 13.5 at the battery, but i only show 12V at the fuse box. My gauge is getting that from the acc on the fuse box directly, so its accurate. how does the fuse box get its power, from the voltage regulator on the alt or the battery its-self? and also i found wierdness with the brown wire coming off the alternator, it has the 4 wire connector instead of the standard one brown wire. The brown wires are spliced together off the alt (there's 2) then down to one wire, then into 2 ceramic block looking resistors at 10 ohms, then spliced into the brown wire on the 4pin power master that is not being used (its vacuum brakes) I have the giant service manual but i cant read it well enough to see if the brown wire is just direct form the alt to the C100 on the firewall or it goes to other places. I know it isnt right, but i cant figure out how to make it factory or at least get me 13.5 like it should. Any help will be appreciated! :biggrin:

 

[Mark E.]

Are you checking both places with the same hand held voltmeter? It was not clear to me in your post.

I know the LT1 alt uses 2 hots to the plug and the stock GN uses only one. But the resistors do not make sense to me. Maybe to bump up the voltage?

If you have 13.5 at the battery and only 12 at the fuse block, I believe you have a fusible link issue.

 

[Mark E.]

The brown wire at the powermaster should work ok. It is a switched 12v. Stock goes through your charge dummy light.

 

[meenkeene518]

yea the battery itsself has 13.5 as does the alternator. 12V only at the fuse block which i checked with an acc then grounded to the battery, then grounded to chassis closer not much change. Which fuseable link would be the problem? i did replace the starter about 2 years ago so most of that near there is new.

 

[Mark E.]

There are a few fusible links feeding different circuits. You should be able to isolate it that way. But if I was going after one bad 23 year old fusable link, I would change them all.

This is a little strange. Usually the go open all together. But this is all assuming unmolested wiring. I think yours has been molested.

 

[Mark E.]

Looks like there are 3 fusible links.

1 goes to the fan relays. Red wire.

another goes to lights and cig-clk fuse. Check at cig-clk fuse.

last goes to ign switch and theft det option. Check at stop-haz fuse.

Check voltage at those 3 places.

 

[meenkeene518]

cool thanks for the locations. i have the gigantic service manual but for whatever reasons the sections in that lelectrical portion are missing somewhere. I assume then if i have a low voltage at any one of those 3 then that fusable link is bad and needs to be replaced?

 

[Mark E.]

Thats the idea. Its a place to start.