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Over the past year since I got this truck I've traced some electrical issues and fixed what I could and ran across a few plugs I couldn't ID. Let me know what you guys think:
Green Plug #1 (On the driver's side under the steering column)
Green Plug #2 (On the driver's side under the steering column)
Driver's side under hood #1
Driver's side under hood #2
Emergency Brake Pedal Plug #1
Starter solenoid terminal..the red wire runs to a trailer brake/light system. Is this terminal stock or just a convenient way to wire things?
Plenty of our trucks come equipped with extra plugs for optional things like roof mounted clearance lights, CB radios, dual batteries and trailer power. I've seen the green plug discussed before I'm pretty sure. Might be for the clearance/running lights.
What color are the wires? I see Yellow, but are their stripes, and what is the other color?
Under the hood the double-square female looks like an old backup lamp switch for a manually shifted three-on-the-tree shifter. I'll see if I can find anything like that under my '79, but I don't remember one.
The oval/roundish one next to it is common for emissions control devices (many of which your '78 should have had), and other newer accessories.
That style of connector was used heavily for ignition and smog control stuff starting in '73 on some vehicles, and maybe earlier on others. Again though, what color wires are present? Maybe we can determine it's specific function that way.
I've seen the green plug discussed before I'm pretty sure. Might be for the clearance/running lights.
What color are the wires? I see Yellow, but are their stripes, and what is the other color?
Looks like a yeller with a black stripe, and a light blue. I don't see a red stripe on that light blue-looking wire, but I was thinking that that's the radio plug till I went back and read that it's outboard of the column.
Under the hood the double-square female looks like an old backup lamp switch for a manually shifted three-on-the-tree shifter. I'll see if I can find anything like that under my '79, but I don't remember one.
I think you're right.
The oval/roundish one next to it is common for emissions control devices (many of which your '78 should have had), and other newer accessories.
That style of connector was used heavily for ignition and smog control stuff starting in '73 on some vehicles, and maybe earlier on others. Again though, what color wires are present? Maybe we can determine it's specific function that way.
My truck might have that extra ignition module-looking plug too, but I can't remember for sure.
The black wire off the batt + side of the starter solenoid is routed to a circuit breaker (not stock), probably feeding the trailer wiring harness to the 7 pin connector on the rear hitch.
There are some Yellow w/black wires in the lighting circuits, but the radio power is also Yellow w/black. Given it's location then, and the color of the connector it's probably the radio like '77F250 said.
You could check for voltage on the Yellow w/black's connector with the key ON and in ACC positions. If it comes on with the key, it's the radio. If it comes on with the headlight switch, it's the cab clearance lights maybe.
Not sure what the light blue is at the moment.
There is also a Yellow w/black wire as part of the ammeter shunt. Does your instrument cluster have an ammeter, or only the CHG indicator lamp?
Either way though, it seems that this would be part of another connector, and not on it's own.
The green plug under the dash looks just like my 77 F-100 AM radio plug.
Two wires going into it: Light blue / red stripe is for the light for the radio, the black (if I recall correctly) is power for the radio.
I think the one on drivers side under the hood goes to your back up light switch. Mine is behind the wire clip and it leads under the steering sector to the top side of the transmission. You can see the wire clips attached to the flange.
Over the past year since I got this truck I've traced some electrical issues and fixed what I could and ran across a few plugs I couldn't ID. Let me know what you guys think:
Green Plug #1 (On the driver's side under the steering column)
Green Plug #2 (On the driver's side under the steering column)
Driver's side under hood #1
Driver's side under hood #2
Emergency Brake Pedal Plug #1
Starter solenoid terminal..the red wire runs to a trailer brake/light system. Is this terminal stock or just a convenient way to wire things?
Whats with all the red wires? Is it heatshrink or something? You also have a red marette connector you need to get rid of, as they are illegal on automotive electrical repair. Start by removing all the added on electric wiring, fix the actual problem, and cover or join splices with heat shrink butt connectors or covering small holes from clamp splices with liquid electrical tape. Hope my advice helps .
You don't need to repeat the pictures in a reply. I don't know what a "red marette" is but there's no such thing as an "illegal" auto electrical repair. Bad, yes.
