2004 6.0 no reverse lights
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4wd Low
Joined: Jan 2014
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2004 6.0 no reverse lights
So I'm having trouble tracking this down... No backup lamps on either side. Manual says fuse #8 on diesel models, fuse tested 12v on both sides..
I pulled the main loom plug under the bumper and ID'd the pins at that plug on the lamp side. Tested the plug side (under bumper) going to the fuse panel and see no voltage on this pin when I put it in reverse., but found it had 170 ohms to ground on what I think is the positive pin - does this sound right??
I ran a visual on the loom from front to back, saw no evidence of damage, and under the dash and fuse panel looks clean, no evidence of rodent activity.... ideas??
I pulled the main loom plug under the bumper and ID'd the pins at that plug on the lamp side. Tested the plug side (under bumper) going to the fuse panel and see no voltage on this pin when I put it in reverse., but found it had 170 ohms to ground on what I think is the positive pin - does this sound right??
I ran a visual on the loom from front to back, saw no evidence of damage, and under the dash and fuse panel looks clean, no evidence of rodent activity.... ideas??
Fleet Owner
Joined: Nov 2003
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You should only have power at the reversing light connector (from Fuse #8) when the PCM commands (actuates) the control side of the "reversing lamp relay. In other words, the PCM needs to know that the transmission is in reverse before it sends power to the light. So if you tested for voltage when the transmission was not in reverse, or if the PCM doesn't know it is in reverse (for whatever reason), then you SHOULDN'T see power there.
Also, the ground resistance is too high ........ if it is simply from Pin 1 (ground) of the reversing lamp connector to system ground. If the resistance is between the negative and positive wires, then that is acceptable "isolation" I suppose. The reversing light's ground goes to the G400 ground (drivers side behind rear bumper). Sounds like some cleanup might be needed there.
Otherwise, possibly the reversing light relay which appears to be relay 211 in the Central Junction Box, or the CJB itself.
Also, the ground resistance is too high ........ if it is simply from Pin 1 (ground) of the reversing lamp connector to system ground. If the resistance is between the negative and positive wires, then that is acceptable "isolation" I suppose. The reversing light's ground goes to the G400 ground (drivers side behind rear bumper). Sounds like some cleanup might be needed there.
Otherwise, possibly the reversing light relay which appears to be relay 211 in the Central Junction Box, or the CJB itself.
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4wd Low
Joined: Jan 2014
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Ok, this one is solved, after getting a paint job (no body work), somehow some act of nature nicked the reverse wire, put a piece of tape on the dead end, and left the live end hanging in open air, it was so stubby it was hard to see as it was at the split just past the main plug under the bumper... or possibly this was in an effort to troubleshoot why some other lights were dead.
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