Electrical Issue

[Racer2172]

So I have discovered I have some electrical issues on my 68 C-10. Question is what have you all found as your most common electrical issues on your projects or these trucks. So far I have a headlight switch that is itermittent and now when i turn the headlights on the turn signals quit working and the radio turns off. Which the radio I just rewired the previous owners nightmare of power and clock wire, wired to a wire nut straight off the terminal board next to the battery. Im thinking that the fuse block has some corrosion or bad grounds. Also the battery tends to be drawn in after a day or two sitting if left connected. Any inputs?

[garyd1961]

I'm no expert on electrical stuff but I do know most of the electrical problems on these old trucks are caused by bad grounds. I would check every ground wire I could find and even add a few here and there. I have my battery grounded to the engine block and a ground from the engine block to the frame. I also have the the motor grounded to the firewall. Also from the bed to the frame, you can't have too many grounds. All electrical stuff needs a clear path back to the negative on the battery.

[dmjlambert]

Most common that I've observed on my truck or read on the forum:
1. Switches gone bad. My turn signal switch, hi-lo beam switch, headlight switch, A/C fan switch were all inoperative.
2. Rat eaten wiring. Rats made a meal of the wires going under the bed to the back of the truck for the tail lights, and the wires going through the driver side front fender to the headlights and alternator, and the wires at the passenger side headlight and turn signal light. I replaced all those sections of wire with same or bigger gauge wire sections soldered in with heat shrink tubing, and re-wrapped the harnesses with non-adhesive black vinyl tape. Then inspected every inch of wire everywhere else for damage.
3. Previous owner damage. I think this is a common one, because Junior just had to use scotch locks, wire nuts, and butt connectors, to cut into the wiring of Dad's truck in the 80's and add big speakers, more stereo, equalizer hanging under the dash, KC lights in front and back, and trailer connector for the boat he shouldn't have bought, and do what he thought was fixing things the farm rats ate, etc.
4. Removal and replacement of things such as engines, carburetors, alternators, regulators, battery wires, and body parts for body work, and then when those items go back on, the wires are left over, "what the heck is that for?" is uttered as it gets tossed on the floor and forgotten about. Or the helper friend says during a mechanical job "just cut that wire, you don't need it." That's probably what happens to most grounds, as I don't think grounds go bad very often. Just what the rats eat. Most of the grounds are attacked by people doing work (or trying to).
5. Corroded fuse block. Disconnect the battery, remove the fuses, use very small wire brush or dremmel to clean up the rust, inspect the back of the fuse block. Put back together. Use a thin layer of bulb grease on the fuse holder terminals. No grounds are in the fuse block.

Battery tends to be drained while sitting could be many things. There are troubleshooting methods you can find here on the forum to figure that out. It starts with disconnecting the crud Junior added, such as stereos, under dash stereo power boosters, accessories that are not stock, etc. Bad alternator or regulator can drain the battery. A bad battery can drain itself.

You can turn off everything and disconnect the negative battery lead, then attach a multimeter set on amps between the negative battery cable and the negative battery post. Your multimeter probably has a 200 mA range on it for you to use. You should get 0 mA or very few mA if you have accessories like a clock or radio with memory and clock. If you have a higher reading, remove the fuses one at a time until you find the circuit that is causing trouble. If trouble not found after disconnecting the fuses, and disconnecting radios and clocks, and disconnecting the alternator and regulator terminal plugs, then ask questions here.

[HotWheelsFan]

Just worked on my 1970 C20.

It had a wire burn recently. Caused by wrong gauge wire and rusted fuse box terminals.

Also had bad grounds and poor connections to bulbs.

Bad headlight dimmer switch. Headlight switch works, but kinda sloppy.

I have had to modify the engine harness in the past for updated electronics. Halogen headlights, HEI distributor, integrated alt regulator, secondary starter solenoid, and previous owner damage.

50 year old wiring can be questionable and sometime problem causing. Remember wiring problems can start fires, cause engine to lose power, and lighting failures.

Bob

[Racer2172]

Thank you everyone for the input, time to dig in and start working the bugs out.

[toolboxchev]

Start by cleaning, wire brushing all the grounds all the way around the vehicle. You will fix and find more problems easier that way.