Grounds?

[83swb]

I'm working on reassembling my truck, and over the course of 3 years I've forgot what grounds I need, and which ones go where. Not to mention wiring is rocket science to me.

The frame and harnesses are original for an 84 C10 (mildly hacked), but the cab and internals are from an unmolested 87' R20.

I know the basics, negative cable to block, tank sending unit strap, taillight grounds, and headlight/marker grounds. I vaguely remember there being a strap between the cab floor and the frame on the drivers side, but I can't find one on the 87' cab, should I run one?

Is there anything I'm looking over? I like pictures and schematics.

[Just call me Sean]

You can't have too many grounds.

[Dead Parrot]

On my 75, there is one from the firewall to the passenger side back outside valve cover bolt. Now would be a good time to replace both battery cables. Get one for the negative side that has both the main cable for the block and also has a smaller short wire and connect the smaller wire to the fender.

[hatzie]

I have several grounds... Stock???
All of the squares with the Delco SI alternators run the battery ground to the alternator bracket.

I have a 6.5L transplant.
I ran the heavy battery grounds to the frame rails near the motor mount.
Heavy braided straps from the motor mount bolt on the block to the frame stud attached to the battery cables on both sides.
From both batteries to the inner fenders. (Small Gauge wire direct to battery)
Braided strap from the frame to the radiator support.
Braided strap from the rear of one cylinder head to the firewall.
Braided strap from the inner fender to the heater fan retaining bolts.
Braided strap from the frame to the bed on both sides.
I've seen braided straps from the inner fenders to the hood dangling along the hinges on some HAM operators trucks. I didn't bother with those.

[Bigstevex4]

There are grounds for head lights park lights on each side front 1 in rear under tail light.

[gmachinz]

The front lighting harness has a ground on each side of the core support. The RH ground location also has a 10ga ground to frame and to negative terminal of the battery. There are two ways to make sure you have a good ground-use either grounding ring terminals OR if using regular ring terminals make sure to also use a grounding washer underneath it. The grounding terminals and washers have teeth to "bite into" the metal for good contact through the paint.

[Bigstevex4]

Originally Posted by gmachinz

The front lighting harness has a ground on each side of the core support. The RH ground location also has a 10ga ground to frame and to negative terminal of the battery. There are two ways to make sure you have a good ground-use either grounding ring terminals OR if using regular ring terminals make sure to also use a grounding washer underneath it. The grounding terminals and washers have teeth to "bite into" the metal for good contact through the paint.

Do you think those star like washers make areal good ground? I grind paint off put dialectric grease and bolt surface to surface . i couldnt get my Road Glide to make agood ground with them.

[gmachinz]

Yes....they break into the surface and bite. Its better than laying flat.

[rich weyand]

Grounding is easy to think through. The battery, the engine, the frame, and the cab are all isolated from each other by rubber mounts and the like. Their grounds all need to be hooked together for electrical stuff to work. Four things need to be hooked together, so there are three grounds required to hook them together.

1) The big one that handles the starter current connects from the battery to the alternator bracket. That connects the engine and battery together.

2) That battery cable also includes a smaller gauge wire for connection to the radiator cross-member right by the battery. That handles the frame connection to the battery.

3) A copper braid connects from the passenger side outboard rear valve cover bolt to the firewall. That handles the cab connection to the engine. You can use a 12AWG wire instead of the braid if you want. The valve cover bolt is where many are connected; better is to hook to one of the accessory mount holes on the back of the head.

So you can see the ground connections are frame to battery to engine to cab. Only the one from the battery to the engine needs to be a really big wire, as it handles the starter current.

In addition, every item that uses electricity has to connect to the battery, the engine, the frame, or the cab to complete the electrical circuit. The starter only has the hot wire to it; it grounds through the engine. The heater blower motor only has the hot wire to it, it grounds through its own frame to the firewall of the cab when you bolt it down. The front lights need a ground to the frame on each side, the tail lights use a ground connection to the frame on one side, with a ground wire traveling across to the other side. (Note: I think some years had tail light grounds on both sides.) There are things in the cab/dash that ground to a multi-bladed ground bar up under the dash next to the parking brake pedal bracket.

That's it really.

Oh, and do replace both battery cables. At some point after 10 years, they corrode internally and give hard starting with no outward sign of anything being wrong.

[83swb]

Thank you very much for that, definitely cleared it up.

[rich weyand]

Glad to help. Sometimes we over-think things, and make them harder than they need to be.