Massive electrical issue, had this before?
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Tuned
Joined: Aug 2017
Posts: 337
Likes: 179
Massive electrical issue, had this before?
Hi all,
Been struggling with an electrical issue with my 79 F150 302 autoC4. Here is the concern:
Hard or extended crank on cold and hot start. Then when running, all major electrical systems run at a reduced speed or cut out all together. Lights flicker, HVAC cuts off or blows low on high, wipers go super slow, no radio, temp gauge bounces all over the place as does the fuel gauge, etc. The alternator gauge reads normal while running and is probably about 8 years old but could be bad, may test that today. The neutral safety switch is probably bad as I need to start in neutral often, but was fine before this concern began. My thought is that a body ground is off or cut somewhere. Here is the current service history to help eliminate the obvious:
Brand new within last 3 months:
battery (700 CCA) (today)
battery cables and terminals
starter
starter solenoid
plugs, wires, cap, rotor
ign coil
ign switch
ign box
fuse box passes visual inspection for burns
Motor has 40K on it and has all new service parts around it, belts, hoses, carb, etc.
I have owned the truck for 20 years, dash has never been out of it.
Thanks all for your help on old blue.
Been struggling with an electrical issue with my 79 F150 302 autoC4. Here is the concern:
Hard or extended crank on cold and hot start. Then when running, all major electrical systems run at a reduced speed or cut out all together. Lights flicker, HVAC cuts off or blows low on high, wipers go super slow, no radio, temp gauge bounces all over the place as does the fuel gauge, etc. The alternator gauge reads normal while running and is probably about 8 years old but could be bad, may test that today. The neutral safety switch is probably bad as I need to start in neutral often, but was fine before this concern began. My thought is that a body ground is off or cut somewhere. Here is the current service history to help eliminate the obvious:
Brand new within last 3 months:
battery (700 CCA) (today)
battery cables and terminals
starter
starter solenoid
plugs, wires, cap, rotor
ign coil
ign switch
ign box
fuse box passes visual inspection for burns
Motor has 40K on it and has all new service parts around it, belts, hoses, carb, etc.
I have owned the truck for 20 years, dash has never been out of it.
Thanks all for your help on old blue.
Senior User
Joined: Feb 2018
Posts: 108
Likes: 1
Had a similar issue on my 78. Check your grounds first. I ended up adding a ground from battery negative to the inner fenderwell. The ground from battery to engine was ok. Then I added a ground from engine to frame . Cured all my ills, including flickering lights, radio cutting out, blower motor drawing down. Ran better to boot! Before this I had already replaced headlight switch, dimmer, put in headlight relay. It was only after I added an aftermarket voltmeter that I could see what was happening. Every time I hit a bump, the voltage would drop to 9! After I added my grounds, I had 14.5 volts and it doesn't vary vary much.
Senior User
Joined: Feb 2018
Posts: 108
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Tuned
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Mountain Pass
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Had a similar issue on my 78. Check your grounds first. I ended up adding a ground from battery negative to the inner fenderwell. The ground from battery to engine was ok. Then I added a ground from engine to frame . Cured all my ills, including flickering lights, radio cutting out, blower motor drawing down. Ran better to boot! Before this I had already replaced headlight switch, dimmer, put in headlight relay. It was only after I added an aftermarket voltmeter that I could see what was happening. Every time I hit a bump, the voltage would drop to 9! After I added my grounds, I had 14.5 volts and it doesn't vary vary much.
Thread Starter
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Tuned
Joined: Aug 2017
Posts: 337
Likes: 179
I figured out the issue, when I put the new battery terminals on, it didn't have the additional ground lead from the neg terminal to the body. It is amazing how much a bad ground can cause so many issues!
Senior User
Joined: Dec 2018
Posts: 152
Likes: 3
From: NEPA
I got battery to engine, battery to fender, engine to cab, cab to hood, cab to frame and cab n frame to bed. Prolly overkill but everything is working. I get really nice stainless braided ground straps through work so might as well splurge.
Senior User
Joined: Feb 2018
Posts: 108
Likes: 1
You got it fixed before I could respond lol. Good job!
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