stumped on tail lights
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stumped on tail lights
I've got an 86 f150 4.9L 4x4. Great truck aside from I can only get one tail light to work. I have done all of the things obvious to me: change the bulb, check the grounds, voltage test, change headlight switch, check fuses. I even changed the dimmer switch and put in a different socket. Still the same issue...
Im really kind of out of ideas here
Any help would be fantastic. Thanks in advance!
Im really kind of out of ideas here
Any help would be fantastic. Thanks in advance!
Posting Guru
Joined: Aug 2005
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Voltage test is not a reliable way to test. Best method is with a test light. The ones with sharp pointed probe and bulb in the handle with a ground pigtail. With no bulb in socket, use the sharp test lite in middle of either contact and pigtail to ground which is the sides of bulb holder. One of the middle contacts is brake/turnsignal and other is running lites.
Moderator
Joined: Nov 2007
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From: Denver Metro Area, CO
You say you can get only one tail light to work but I need you to be more specific... the
running lights? Or the brake/turn signal lights? If the latter, there are many possible
causes, including the turn signal switch.
Moderator
Joined: Nov 2007
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From: Denver Metro Area, CO
Running lights are the brown wire. If you have battery voltage at the brown wire's contact in
the socket, and the brake/turn signals are fine yet the running light won't light, are you using
the correct bulb? I believe it's an 1157 and it should install in only one orientation.
Next thing to come to mind is the bulb isn't coming into contact with the electrical contact at
the bottom of the socket (different guy here recently had that problem with some fancy-
dancy bulbs he had gotten from someplace).
The test light is a good idea, you can fake it using a short piece of stranded wire to go
between the suspect contact in the bottom of the bulb housing to the correct contact on the
bulb, then ground the brass part of the bulb, it should light.
the socket, and the brake/turn signals are fine yet the running light won't light, are you using
the correct bulb? I believe it's an 1157 and it should install in only one orientation.
Next thing to come to mind is the bulb isn't coming into contact with the electrical contact at
the bottom of the socket (different guy here recently had that problem with some fancy-
dancy bulbs he had gotten from someplace).
The test light is a good idea, you can fake it using a short piece of stranded wire to go
between the suspect contact in the bottom of the bulb housing to the correct contact on the
bulb, then ground the brass part of the bulb, it should light.
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Ok, so an update on the situation: Took a test light to it the wires themselves. With just the headlights on, the wire to the passenger running light gets no power. When the brake is pushed, power is there.
Furthermore, to appease my curiosity. I took the socket and ran it straight from the battery. The bulb will light properly that way, which I assume means the socket and connection to the bulb are fine.
Furthermore, to appease my curiosity. I took the socket and ran it straight from the battery. The bulb will light properly that way, which I assume means the socket and connection to the bulb are fine.
Post Fiend
Joined: Dec 2007
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From: Lost
Got a trailer light connector on the truck? If so, trace those wires to where they join the wires running from the left frame rail, over towards the passenger tail light. Good chance you'll find the problem there, if it has the trailer connector added......
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Fleet Mechanic
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From: West Valley City
I had this same problem. Changed out the turn signal switch and that solved it. There was a wire getting pinched by the plastic column cover. Apparently the lighting system works in loop, so as to cancel another light out when its needed. Good luck and I hope you get it fixed.
Posting Guru
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I had this same problem. Changed out the turn signal switch and that solved it. There was a wire getting pinched by the plastic column cover. Apparently the lighting system works in loop, so as to cancel another light out when its needed. Good luck and I hope you get it fixed.
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Apologies for the long response time...The trailer lights indeed were the issue. While it appeared to be neatly wrapped...the wire connections and routing were trashed. I removed the trailer wiring and re ran the original wiring according to the diagram. Now the lights work fine. Figures something simple. Thanks a million to all of you for your help.
Elder User
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From: South Jersey
Apologies for the long response time...The trailer lights indeed were the issue. While it appeared to be neatly wrapped...the wire connections and routing were trashed. I removed the trailer wiring and re ran the original wiring according to the diagram. Now the lights work fine. Figures something simple. Thanks a million to all of you for your help.