Electrical Demons continue

Reply Subscribe

Thread Tools

Search this Thread

Dec 6, 2018 | 08:42 AM

'79BabyBlue

Thread Starter

Freshman User

Joined: Nov 2018

Posts: 26

Likes: 0

Electrical Demons continue

So, on my 1979 F150 custom... I have all lights brake, tail lights, turn signals, markers.... untill I pull on the headlights.

Then; I loose some of the lights. I'm not an electrician.....

Do I continue to replace each bulb and fuse? Or is there a better way to troubleshoot the exact cause. I have checked the physical wiring and can't see anything worn, broken, or melted.

Dec 6, 2018 | 08:49 AM

meangreen92

Logistics Pro

Joined: Jul 2005

Posts: 4,217

Likes: 154

Inspect for proper grounding. There should be a ground for each headlight. I think they go from the headlight connector harness to the radiator support where they are secured with a bolt.

And inside each taillight cavity is an identical ground which is screwed to body metal inside there. Gotta pull the tail light out to see it.

Then there is a ground which goes from the back of your engine to the firewall.

Lastly there is a ground from your instrument panel harness which is screwed to the steering column brace.

Definitely check those first five grounds I listed. I'm not sure if the IP ground can cause that.

And double check any dual-filament bulbs to make sure they're not installed 180º out of phase.

Dec 6, 2018 | 10:55 AM

84espy

Fleet Mechanic

Joined: Nov 2009

Posts: 1,398

Likes: 6

Since all your lights are working BEFORE you turn on the headlights, I would replace the light switch. It sounds like something is amiss internally on the switch.