Wiring
Thread Starter
|
New User
Joined: Dec 2009
Posts: 16
Likes: 0
From: Oak Grove, Kentucky
Wiring
Brake lights work, turn signals work, until I turn on the lights as soon as I do that nothing in the rear end works. I was told it was a short somewhere but I have checked everything but I can't find anything that might cause it. Any ideas?
Senior User
Joined: Sep 2003
Posts: 238
Likes: 0
From: Bridgeville,CA
It sounds more like a dirty connection to me. A short should cause a fuse to blow. If one of the connectors is corroded then when you turn on a heavy current draw like the headlights the voltage drop across the connector would cause the voltage of everything past there to be lower than normal. What is the voltage at the stoplight without the headlights on vs with the headlights on? The best way to find the problem is start walking through the system from where you have 12v until you find a drop. Do you have a wiring diagram?
Laughing Gas
Joined: Jun 2007
Posts: 811
Likes: 4
I think the headlights are a red herring. When the headlights are turned on, you are also turning on the tail lights. You said all of the lights in the back go out. The tail lights, brake lights and turn signals are all part of the same harness. I would bet that you have a bad ground somewhere in the tail light harness.
Senior User
Joined: Sep 2003
Posts: 238
Likes: 0
From: Bridgeville,CA
I am not sure that it is a ground issue. Everything is grounded thru the frame so there is no common ground, but what hp246 said is still valid, a bad connection somewhere. I have had this kind of problem on both my 69 F100 2wd and my 73 f250 4wd and it has always been one of the harness connectors. They look like several bullet connectors in one unit. There is one on the left side near the rear that carries everything to the rear. (4 wires) Try unplugging it and plugging it back in several times. Couldn't hurt. It is behind the left rear wheel and gets bombarded with everything (water, salt, dust, etc.) that the wheel throws at it.
Laughing Gas
Joined: Jun 2007
Posts: 811
Likes: 4
When I say bad ground, it could be a million things. A broken ground wire, a dirty connection. Could even be in the switch.
One other thought. I saw this once. Have the tail light bulbs been changed recently? I saw a case where the wrong bulb was used. A single filament parking lamp bulb was put in instead of the tail light bulb with two filaments. Had a similar problem.
One other thought. I saw this once. Have the tail light bulbs been changed recently? I saw a case where the wrong bulb was used. A single filament parking lamp bulb was put in instead of the tail light bulb with two filaments. Had a similar problem.
Thread
Thread Starter
Forum
Replies
Last Post
bjceleste
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
3
Jan 9, 2013 10:31 AM
