OK, I finally decided to tackle the wiring mess on my 83 suburban. The guy I bought if from said that he had replaced a blown fusible link with a couple of fuse holders, and, it looks like that's just what he did.
Well, I've been having trouble with low voltage at idle, especially with the front and rear A/C running. I figured I was just overloading the alternator, so I picked up a 135amp unit and tossed it in. That didn't help. I pulled out the trusty DMM and started feeling around. It appears that I'm getting a 2-3 volt drop between the battery and the power lug on the firewall. After peeling off a 1000 or so feet of electrical tape this is what I found. It looks like he came off a 10ga power feed, split it in to 2 fuse holders (to replace the FL I guess), then ran the two wires back to the same point at the solenoid. He had 30 amp fuses in each of the holders. I had one of the two fuses blow (the melted socket), and I lost all power inside the vehicle, so I would have to guess the holder or one of the wire crimps is bad.

So, here are my questions.

What should the rating of the fusible link be? I'm guessing 60 amps, but my (not so) trusty chilton manual doesn't tell me squat.

What does this 'fuse looking' (That’s a technical term btw) power lug on the firewall feed? It splits off in to the firewall from the passenger side, and appears to feed the fuse block on the driver’s side. Is this correct, or does that one on the firewall feed the ignition switch, and the one near the battery feed the fuse block? My wiring diagram says the ignition is fed from a battery fusible link, but I don't see a connection in the diagram.

http://home.earthlink.net/~ekronsprint/wiring/fusablelink.jpg

Also, my Chilton shows terminal 2 of the alternator tied right back to the batt connection on the alternator. If I remember correctly, shouldn't that be fused so the field isn't always charged resulting in battery drain? I was considering rewiring this whole circuit. Whenever I converted from an external regulated alt to an internal, I always ran the 'Batt' terminal straight to the battery and the #2 to a switched source. Is there any reason that wouldn't work in this scenario?

http://home.earthlink.net/~ekronsprint/wiring/diagram.jpg

The fuseholders:
http://home.earthlink.net/~ekronsprint/wiring/fuseholders.jpg

Any help is appreciated.

I used to work for a school bus company that had all kinds of wiring problems at the starter due to the amount of heat generated by the engine and the exaust manifold. This is a fix direct from GM. They actually recommend using a ford starter solenoid. Mount the soleniod somewhere on the inner fender. Using a minimum of 2 ga. wire for battery cables. Hook them up appropriatly. At the starter use about a 5-6" piece of 10ga. and loop from where the batt. cable bolts to the S term on the solenoid. Up top, you will have to extend the factory wires to the ford solenoid and hook them to the batt. side of the solenoid. The factory purple wire goes to the S terminal on the solenoid. At the alt. you can loop the wire directly to the output post. And from the output post if you have a 135a. I would recommend 8ga. to the battery or the solenoid. The junction block on the firewall, cut the metal piece, so that it does not extend to the other post. This is where you connect your fusible link which should be 12ga. about 4-5 inches long. and of course from one post to the other. Have fun, not really that difficult just timle consuming to do it right, It also makes it nice if you have to crank the engine over for service work under the hood.

I have tore apart MANY GM harnesses and they all are pretty much the same. (Got to love the commonality stuff, engine, trannys, wiring etc...) Anyway, the power comes from the battery to the starter. It then goes up to the junction block, (technical term for the black plastic piece with the studs sticking out). From the junction block, it goes to the alternator and the fuse panel under your dash. The actual switching of power comes from the key switch on the column. This is where all the other large powered wires comes from like the starter wire, (starter wire - large puprle wire).

You can take out the fusable link without too many problems BUT!!!!! here is the big BUT, make sure that you are not having any other wiring problems like grounding out somewhere!!! I have had wiring harnesses which have been butched including the fusabile links. I fixed them by soldering them back together without any problems.


As for the alternator, you are correct. The alternator powered wired is switched. It comes from the ignition switch under your dash. There is no reason that you can not correct "his" wiring by hooking up the alternator BIG RED wire to the junction block and the #2 to a keyed switch wire.

Originally posted by mnstr_fx
You can take out the fusable link without too many problems BUT!!!!! here is the big BUT, make sure that you are not having any other wiring problems like grounding out somewhere!!! I have had wiring harnesses which have been butched including the fusabile links. I fixed them by soldering them back together without any problems.


I finally found a MAXI fuse holder that wil take a 60A fuse, so I am going to replace the crappy little ones the other guy installed so it will sta fused. I'm also going to solder all of the connections where he used crimp connectors. I'm also going to re-end all of the ring terminals. Solder and shrink wrap are my friends tonight! Hopefully this will cure part of the voltage drop.

Originally posted by mnstr_fx
As for the alternator, you are correct. The alternator powered wired is switched. It comes from the ignition switch under your dash. There is no reason that you can not correct "his" wiring by hooking up the alternator BIG RED wire to the junction block and the #2 to a keyed switch wire.

I'm going to fix this circuit too. I have some 8ga but I think I'm going to do a straight shot to the battery rather than the Junction Block, and I'm going to makw sure the current connection to the #2 term is switched.

The worst part of doing all this is getting the electrical tape off of everything. The tape on there now has dried up in to a very tough casing that I literally have to crack and break off. Damn cheap tape! When it's done it will all be in looms and zip ties rather than tape.

Thanks for the info!

your # 2 wire is NOT a switched wire, it is a direct battery 12v to the regulator. The #1 wire is the switched wire from the ignition switch [ the small BROWN 18ga. wire]. It is not necessary to take the extra time and add an unnecessary and more mess under your dash unless you think it is going to 'help' things. If you look at the wiring harness you posted, it hooks directly to a batteery source that's why it is red in color. Why GM added 7 feet of wire to a harness that it didn't need still remains a mystery even to some of the GM techs.

Originally posted by KWTMECH
your # 2 wire is NOT a switched wire, it is a direct battery 12v to the regulator. The #1 wire is the switched wire from the ignition switch [ the small BROWN 18ga. wire]. It is not necessary to take the extra time and add an unnecessary and more mess under your dash unless you think it is going to 'help' things. If you look at the wiring harness you posted, it hooks directly to a batteery source that's why it is red in color. Why GM added 7 feet of wire to a harness that it didn't need still remains a mystery even to some of the GM techs.

I did it right. I was mixing up #1 and #2 in my head. I jumped the #2 term back to the battery post then fed those straight to the battery via 8ga.

It seems to be better now, and the lights are brighter, but the guage still reads a bit low. It's better than it was, but I'm gonna pull the dash apart one more time and actually get a reading off the posts the guage fits on and see how accurate it is.

Thanks for the help!