Need help with rear lights!
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Need help with rear lights!
Hi guys,
have an 02 f350 XL.
the other day it rained and all of my rear lights went haywire.
all problems are out back.
-step on brakes, high mount, and lic plate lights light up with brakes.
-turn on marker lights and the high mount lights up and the tails and lic plate lights dim.
-marker lights on, apply brakes, and the tails and lic plates lights go out on bed, high mount activates.
-use turn signals with markers off and all of the rear lights including high mount flash..
-reverse lights dim or dont work at all.
i have tried a new MF switch, checked all fuses. cleaned rear frame ground. took apart brake switch and cleaned it. non tilt column but checked wires. replaced flasher. unplugged brake light switch and headlight switch, problem is still there. removed trailer relays, no help. checked all chassis plugs. disconnected TRS.
i should mention i have 12v cummins swap and a pcs with standalone harness. no problems over the last few months since swap until it rained last monday.
need help/suggestions!!
have an 02 f350 XL.
the other day it rained and all of my rear lights went haywire.
all problems are out back.
-step on brakes, high mount, and lic plate lights light up with brakes.
-turn on marker lights and the high mount lights up and the tails and lic plate lights dim.
-marker lights on, apply brakes, and the tails and lic plates lights go out on bed, high mount activates.
-use turn signals with markers off and all of the rear lights including high mount flash..
-reverse lights dim or dont work at all.
i have tried a new MF switch, checked all fuses. cleaned rear frame ground. took apart brake switch and cleaned it. non tilt column but checked wires. replaced flasher. unplugged brake light switch and headlight switch, problem is still there. removed trailer relays, no help. checked all chassis plugs. disconnected TRS.
i should mention i have 12v cummins swap and a pcs with standalone harness. no problems over the last few months since swap until it rained last monday.
need help/suggestions!!
New User
Joined: Oct 2011
Posts: 17
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From: Lebanon
Hi guys, have an 02 f350 XL. the other day it rained and all of my rear lights went haywire. all problems are out back. -step on brakes, high mount, and lic plate lights light up with brakes. -turn on marker lights and the high mount lights up and the tails and lic plate lights dim. -marker lights on, apply brakes, and the tails and lic plates lights go out on bed, high mount activates. -use turn signals with markers off and all of the rear lights including high mount flash.. -reverse lights dim or dont work at all. i have tried a new MF switch, checked all fuses. cleaned rear frame ground. took apart brake switch and cleaned it. non tilt column but checked wires. replaced flasher. unplugged brake light switch and headlight switch, problem is still there. removed trailer relays, no help. checked all chassis plugs. disconnected TRS. i should mention i have 12v cummins swap and a pcs with standalone harness. no problems over the last few months since swap until it rained last monday. need help/suggestions!!
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Plug is clean. Had dielectric grease in it since spring b
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i also found that when markers are off and hazards/turns are on i have 12v (flashing) going to both wires for bulb on drivers side and 12v to one wire on pass side.
i should mention that i had a relay hooked up for a reverse light wired as follows. 12v from trailer tail harness, switched from truck reverse circuit, ground from rear chassis ground. is it possible that if that relay got wet (it was wrapped well) that it shorted at the fuse block (cjb)? i pulled all of that relay and wiring out and the problem still persists.
the trans range sensor appears to be wet with some atf (i assume) thats why i unplugged it to make sure it wasnt grounding to the tcm harness. ive been working on this for days, its my dd and i dont want a ticket or accident from faulty equipment.
FTE Remembers
Joined: Apr 2012
Posts: 27,307
Likes: 549
From: Spanaway
In the CJB are some hidden relays. That is why the stupid thing
costs so much to replace. Well that and the fact that from Ford only.
If you find it wet look up to the front glass. Some years had a leaking
problem. You may want to put the truck in and add some heat to dry it out.
The only way to keep things dry is to seal them up. Wrapping with tape is
not always a good thing. Water will find a way in. The heat shrink with the mastic
will keep things dry so long as your able to get it around all the wires and create
a seal. The down side it's a real bitch to remove.
Sean
costs so much to replace. Well that and the fact that from Ford only.
If you find it wet look up to the front glass. Some years had a leaking
problem. You may want to put the truck in and add some heat to dry it out.
The only way to keep things dry is to seal them up. Wrapping with tape is
not always a good thing. Water will find a way in. The heat shrink with the mastic
will keep things dry so long as your able to get it around all the wires and create
a seal. The down side it's a real bitch to remove.
Sean
Thread Starter
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New User
Joined: Mar 2011
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In the CJB are some hidden relays. That is why the stupid thing
costs so much to replace. Well that and the fact that from Ford only.
If you find it wet look up to the front glass. Some years had a leaking
problem. You may want to put the truck in and add some heat to dry it out.
The only way to keep things dry is to seal them up. Wrapping with tape is
not always a good thing. Water will find a way in. The heat shrink with the mastic
will keep things dry so long as your able to get it around all the wires and create
a seal. The down side it's a real bitch to remove.
Sean
costs so much to replace. Well that and the fact that from Ford only.
If you find it wet look up to the front glass. Some years had a leaking
problem. You may want to put the truck in and add some heat to dry it out.
The only way to keep things dry is to seal them up. Wrapping with tape is
not always a good thing. Water will find a way in. The heat shrink with the mastic
will keep things dry so long as your able to get it around all the wires and create
a seal. The down side it's a real bitch to remove.
Sean
Its a perexing problem. The only thing the highount and the rear lights have in common is the brake light feed pre mfs.
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In an XL model truck i think the VSM is built into the cluster. I unplugged it and the dome light shut off like it should. But the rear lights still act up. Im going o have to just bite the bullet and start pulling harnesses.
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Yeah i have alldata through work. Been staring at diagrams for a week lol. Im adding ground straps right now
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I got it figured out just no idea why took so long for the problem to surface. I cummins swapped the truck and never grounded frame to cab. Been three months running it daily. I put in a 4ga ground from core support to the steering box bolts. Perfect, lights are ten times brighter! Thanks everybody!
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