Does anybody know what relay powers the box lights on a 1996 FL 70.I have never had problems with the top marker lights until I had the rear door sanded ,painted and made to look nice so FDX would extend my lease for 1 more year. I was stopped by the GA DOT for a class 1 inspection and the all of the marker lights were out. I played with relays,wiring fuses and could not get them back on.Today I took the truck back to the trailer repair facility that did the door and while me and the mechanic were looking at the top of the box the damn lights came on. He did some wiring checks,all looked OK so you can!t fix what is working. I think it is a relay but the Medium Duty Manual has about 3-4 relays that all say Trailer and marker lights. I am not certain which one it is , but if I find out , I will change that one just in case. MP do you remember from your FL 70 days which one they used,if all else fails I just may pull relays until the lights go out. Could the Headlight switch also be at fault? Don!t we all love intermittent problems?
FL 70 Box lights
- Thread starter RichM
- Start date
On most FL70's the box marker lights are on the same relay and breaker as the cab marker lights. You most likely have a supply or ground wire that is intermittently becoming open somewhere- is't most likely the supply one as they tend to get brittle from the small amount of heat they generate and break, but not all the way at first so it works sometimes. If it were shorted it would kick the braker on and off about every 10-15 seconds.
Seeing its all the box lights, start tracing the power from the source cable- it starts at the cab, and usually into the box at the passenger side rear by the taillights there. The marker power wire is most often the brown one in the cable. While the lights are still on, wiggle every connector you see under the truck first- they rot out the fastest from water and salt. You'll probably come across the culprit quicker than you think. Try it at night too- easiest then as the intermittent wire will spark a little bit. Once you find the bad spot, you can make an easy crimp jumper to fix it, then seal it off from water. Also look at the wires around the area on the box that was worked on. Someone might have inadvertently moved a weak spot, and cracked the wire open there.
Good luck!
-Weave-
Seeing its all the box lights, start tracing the power from the source cable- it starts at the cab, and usually into the box at the passenger side rear by the taillights there. The marker power wire is most often the brown one in the cable. While the lights are still on, wiggle every connector you see under the truck first- they rot out the fastest from water and salt. You'll probably come across the culprit quicker than you think. Try it at night too- easiest then as the intermittent wire will spark a little bit. Once you find the bad spot, you can make an easy crimp jumper to fix it, then seal it off from water. Also look at the wires around the area on the box that was worked on. Someone might have inadvertently moved a weak spot, and cracked the wire open there.
Good luck!
-Weave-
Freight_Shaker
Expert Expediter
lo guys
I had thew same problem with my 97 fl-70 and it took me a month to find the problem the relay for the box lights is in another fuse panel located in the the tool box compartment of your sleeper on the drivers side that little door that you put all the junk in......just inside on the right hand side there should be a litle flap there with snaps on it thats where mine is anyhow my bunk is made from alumi-bunk and in there will be all the fuses for your inverter and bunk heater and stuff not to mention your box lights.Mine kept burning after i decided to turn my box into a christmas tree filling in every possible space with clearance lights so i'd glow going down the road at night if you dont have that second fuse panel in there then just ask any dealer where the second fuse panel is and they should be able to help you out on mine they soldered the wire together without a fuse and put a relay on the line so it wouldnt burn the fuse all the time hope this helps you in some way.
I had thew same problem with my 97 fl-70 and it took me a month to find the problem the relay for the box lights is in another fuse panel located in the the tool box compartment of your sleeper on the drivers side that little door that you put all the junk in......just inside on the right hand side there should be a litle flap there with snaps on it thats where mine is anyhow my bunk is made from alumi-bunk and in there will be all the fuses for your inverter and bunk heater and stuff not to mention your box lights.Mine kept burning after i decided to turn my box into a christmas tree filling in every possible space with clearance lights so i'd glow going down the road at night if you dont have that second fuse panel in there then just ask any dealer where the second fuse panel is and they should be able to help you out on mine they soldered the wire together without a fuse and put a relay on the line so it wouldnt burn the fuse all the time hope this helps you in some way.
streetsweeper
Expert Expediter
hey gang!
open your rollup against the stops, vise grip it in place so you can see all of your tee wiring harness. alternately and only if you have a side door since you may be working alone on it, secure the rollup in closed, remove the panel adjustment bolt from each top roller, lay the top panel down. viola! you have much easier access to the wiring that way.
check for those 'scotch connectors' the lil blue clamp things. most shops use them for quicky repair. not worth the money you pay for them by the way. my bet is the painter nicked the power wire and did a poor splice repair job to it for the lights to 'suddenly work'.
look for a new butt connector, blue or clear color.....14-16 ga. is the only other connector i think of being used there. don't let them charge you for repairing the lights either. if they worked before the paint job, they'd best after the job too...
open your rollup against the stops, vise grip it in place so you can see all of your tee wiring harness. alternately and only if you have a side door since you may be working alone on it, secure the rollup in closed, remove the panel adjustment bolt from each top roller, lay the top panel down. viola! you have much easier access to the wiring that way.
check for those 'scotch connectors' the lil blue clamp things. most shops use them for quicky repair. not worth the money you pay for them by the way. my bet is the painter nicked the power wire and did a poor splice repair job to it for the lights to 'suddenly work'.
look for a new butt connector, blue or clear color.....14-16 ga. is the only other connector i think of being used there. don't let them charge you for repairing the lights either. if they worked before the paint job, they'd best after the job too...