QUIZ: 78 ground wires
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QUIZ: 78 ground wires
Okay, pop quiz. How many grounds wires are on a 78 and where are they?
I seem to recall reading someplace that there were 5. I also think my wiring is not stock. There was a ground attached to one of the valve covers when I bought it and the wipers stopped working when I removed it. I also have SIX tail light sockets!
I seem to recall reading someplace that there were 5. I also think my wiring is not stock. There was a ground attached to one of the valve covers when I bought it and the wipers stopped working when I removed it. I also have SIX tail light sockets!
Le Mans Master
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
The main ground is from the battery negative post to a crossmember under the drivers seat, make sure that one is good first.
The wiper motor and heater fan ground wire is a black wire and connects to a bell housing bolt next to the starter.
Almost every circuit has it own ground, are you having trouble with the rear lights?
http://www.vetteprojects.com/bmv/mis...tte%201978.pdf
The wiper motor and heater fan ground wire is a black wire and connects to a bell housing bolt next to the starter.
Almost every circuit has it own ground, are you having trouble with the rear lights?
http://www.vetteprojects.com/bmv/mis...tte%201978.pdf
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Peterbuilt,
Thanks for the info and wiring detail. I have nothing except the "gen" idiot light and the battery gage when I try to start it. No lights, no clicks, no wipers. No radio but I took that out so I understand why it doesn't work.
Do you know where the grounds are. I can see they in the schematics but, it doesn't say where they are on the car.
p.s. love Peterbilt trucks!
Thanks for the info and wiring detail. I have nothing except the "gen" idiot light and the battery gage when I try to start it. No lights, no clicks, no wipers. No radio but I took that out so I understand why it doesn't work.
Do you know where the grounds are. I can see they in the schematics but, it doesn't say where they are on the car.
p.s. love Peterbilt trucks!
Le Mans Master
Joined: Aug 2006
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Are you sure that you have a ground problem?
The positive from the battery connects to the top post of the starter solenoid, two other wires also connect to that post.
A red and a red/white, they are listed on the schematic as 'thermo'.
They are fusible links and if they blow no power gets to the rest of the car.
Yes Peterbilt trucks are real nice, here's one I drove for a while.
The positive from the battery connects to the top post of the starter solenoid, two other wires also connect to that post.
A red and a red/white, they are listed on the schematic as 'thermo'.
They are fusible links and if they blow no power gets to the rest of the car.
Yes Peterbilt trucks are real nice, here's one I drove for a while.
Le Mans Master
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From: Myrtle Beach SC
There is an engine ground located on the passenger side near the starter but grounded to the frame. It is about the size of the ground off the battery on the driver's side. I found this ground dangling by a few strands and replaced it.
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Peterbuilt & Hunt4cleanair, you are both correct! Thanks for the help. It's page 476 in the AIM in case any future newbies need to know. I was looking at page 452 which is a little less helpful. Once the starter was all wired up, grounded to the bell housing and frame I have parking lights, dash lights and horn. At quarter to 11 last night I had the epiphany about the clutch safety switch.
If I'm stupid enough to start the car in gear, then that's my right! Don't need GM double checking me. The switch is in my basement so I'm pretty sure there's a gap in the circuit. Need to find the purple wires and bypass the switch. This is getting exciting!
If I'm stupid enough to start the car in gear, then that's my right! Don't need GM double checking me. The switch is in my basement so I'm pretty sure there's a gap in the circuit. Need to find the purple wires and bypass the switch. This is getting exciting!
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HA! I found the clutch safety switch and bypassed it. Worked great. Now I just need to know what the little gizmo that I thought was the switch is? It was connected to the church pedal by a small chain. Like a keychain or light socket pull chain.
Safety Car
Joined: Dec 2012
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From: Summerville SC
there is also a ground behind the front wheel, driver side going from the frame to a piece of steel atttached to the birdcage. Almost like it was added in case there was not a good connection through the front body mount.
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Rather than bypass, put a toggle switch in it and hide it somewhere. It is now your secret Theft Deterrant!