Tail light / turn siginal problems
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Tail light / turn siginal problems
I have a 1986 F-250 4x4 460 4 spd. I removed the bed to change both fuel pumps in the fuel tanks. After replacing the bed and reconnecting the plug for the lights they don't work.I have replaced the bulbs. Checked for power at the plug and there is power.I have checked for power at the sockets and there is power there also. Reinstall the bulb, no light. One thing that is odd is when I touch the tester to the brass on the bulb the tester comes on. The lights all worked fine prior to removing the bed.
Thanks in advance to all who might respond.
Thanks in advance to all who might respond.
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I'm sorry, but when the tester comes on when you touch the brass on the bulb, what is the other side of the tester connected to? And, when you are testing for power at the socket, what are you grounding the tester to?
I think the problem is that you don't have a ground going to the bulbs. I don't remember where the ground wired that goes to the bulbs really is supposed to be grounded, but I'll bet it isn't, that you either took it off when you replaced the bed or somehow disturbed it. So, while you have power at the socket I'll bet you don't have ground there.
I think the problem is that you don't have a ground going to the bulbs. I don't remember where the ground wired that goes to the bulbs really is supposed to be grounded, but I'll bet it isn't, that you either took it off when you replaced the bed or somehow disturbed it. So, while you have power at the socket I'll bet you don't have ground there.
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And, the proof is that when you touch the test light to the brass it comes on. You found that odd because you expected that to be ground, which wouldn't light your test light. But, since the ground wire is not grounded, your test light saw power through all the tail lights due to them having a common "ground", albeit not at zero volts. The tail light filament is a much lower resistance than your test light, so it looks like a pretty solid wire to +12 volts.
Go follow the ground wire from the socket and figure out where it is supposed to ground, probably on the frame by the bumper.
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To prove that is the problem you could jumper the brass from one bulb to the bumper. At that point all lights will work because you've grounded the ground wire they share. May take several hands and another pair of eyes, but it will work - I am sure.
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Does the ground run through the 4 pin connector? Would the pins be running lights, left, right turn and ground?
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That sounds right, but I'll confirm in a couple of hours when I get back home and can look at the wiring diagram.
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The tail light & stop/turn light ground was located in different places during the years. On my 1980, there is a ground wire visible with the light assembly pulled out, it attaches to the bed right behind the light. Later years had it running back to the frame. I do not know if this ground runs thru the 4 pin plug, or is a separate plug, as there are also reverse lights to deal with. I've heard this ground wire is attached to the frame as far forward as the front fuel tank location.
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- Brown - Tail lamp
- Light Green - Left stop/turn
- Light Blue - Right stop/turn
- Black - Ground
Somewhere, and I can't find where, the bed has to be grounded to the frame. I think that is the real culprit, so were it me I would run a ground wire from bed to frame and, assuming it works, be done with it.
Thanks! Glad to help.
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