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wiring for reverse lights


PEIFamily

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Does anyone know what the wires for the reverse lights on a gen2 Volvo route too? Or what wire heading to the backend I can tap into?

 

Started removing my rear lightbar the other day and as I was about to disconnect a few wires, it slipped and disconnected the wires for me.. I wired up all the rest of the lights, but getting errors on the dash regarding my reverse lamps and they are not working.. I have a red wire, black and white coming from the lamp, I am guessing a few of them are wired up into the existing lightbar, but one side of the bar had a spare wire on the reverse lamp not wired into the lightbar and not sure where that routes too.. It was on the white on the light connector.

 

Anyone have a rear wiring diagram?

 

Thanks

 

 

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Thanks, I had them all working. I had attacked some of the rear wiring last fall and cleaned up the rats nest of wiring a bit, but cleaned up a bit more now.. seems the previous owner loved chopping wires and taping things together without using any crimps or anything.

 

4ways, all brakes and parks are working, just the reverse won't work.

 

Thanks for your help :)

 

Jason

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The reverse lights should be fed by the wire in terminal A on the connector Carl mentioned--it should be along the left frame rail, near the rear axle. If you unplug that connection, and look at the female plug, the terminal labels are molded into the connector face. If you can't read those, terminal A is on the end, in a group of 4 pins. The last terminal, E, is the ground and there's a slightly bigger space between D and E than there is between the others.

 

You might also check the LCM to see which codes it is showing. Either an open circuit (nothing connected, or possibly a very poor connection) or a short circuit should generate a fault. Also make sure all 6 LCM fuses are good--I'm not sure which one feeds reverse, and they're not labeled such that you can tell.

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Thanks

 

I will check all my fuses.. Most of the terminal connection at the rear of the truck were hacked up and rewired before I got the truck, the other day when I was cleaning up the harness there was only one wire still not bypassed through it.. I will check the fuses and then do the crossover on the trans switch as a test before checking for power in any of the lines.

 

I have a digital meter reader and I was told the other day by a guy at the campground here not to use it on the truck as it could cause issues with the computer?

 

Thanks

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I'm sure you've figured this out, but just in case...did you start the truck, put it in reverse, then shut it down, then turn the ignition back on. (You have to physically move the transmission internals to get the reverse switch to work. Moving the shifter alone won't get 'er done) That kills everything EXCEPT reverse lights. Take your trusty continuity probe (ice pick on one end, alligator clip on the other) and poke around a bit on the truck side of the broken wiring. Shouldn't take too long to find a hot wire, and that should be the reverse wire. To check, start the truck, take it out of reverse, shut down, and turn the ignition back on. Check the wire again. If it's not "hot", you just confirmed that that's your reverse wire.

 

On our 2001 Volvo 770 the factory ground at the rear of the tractor used a white wire. Running lights & such used a black wire. Don't remember the rest.

 

Good luck!

 

Paul

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Hi,

well, played around with it more, the error I am getting is the reverse lights/marker ICC trailor fault.

 

I ended up rewiring all the 11 lights since a few wires looked questionable in the light bars.

 

I still have no reverse lights, but I ended up hooking the white light from them to the all one ground vs each one having its own questionable ground and then ran another black wire and another red wire for the reverse lights so i didn't need to mess around inside the lightbars anymore.. I tried the truck in reverse, start, shift and leave in reverse and shut off and no real power going through them. I got one with 2v but it has it without reverse being on.

 

Soon as I find a live reverse wire, I will wire them up seperate from the other ones. Also, the white on the reverse is ground, there are two others, red & black. One is for the reverse wire, what is the other wired to?

 

I should be able to find one that has a full 12v from it right?

 

I think I will test a spot a few feet further up and see if I get any power.

 

Next option would be to test the transmission one? Anyone know where the switch is located on a 13 speed?

 

Thanks
Jason

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Before you "test a few feet further up", be aware that if you puncture a wire with the ice pick, you just made a place for corrosion to start. Don't ask how I know.......

 

Rather, find a connector further upstream and test the terminals in the plugs. If you find anything fishy, do and ohm test and look for a broken wire.

 

If you have a manual 13 speed, there can't be that many wires going to it. Perhaps the reverse switch would be the only connection.

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Hi,

well, played around with it more, the error I am getting is the reverse lights/marker ICC trailor fault.

 

I ended up rewiring all the 11 lights since a few wires looked questionable in the light bars.

 

I still have no reverse lights, but I ended up hooking the white light from them to the all one ground vs each one having its own questionable ground and then ran another black wire and another red wire for the reverse lights so i didn't need to mess around inside the lightbars anymore.. I tried the truck in reverse, start, shift and leave in reverse and shut off and no real power going through them. I got one with 2v but it has it without reverse being on.

 

Soon as I find a live reverse wire, I will wire them up seperate from the other ones. Also, the white on the reverse is ground, there are two others, red & black. One is for the reverse wire, what is the other wired to?

 

I should be able to find one that has a full 12v from it right?

 

I think I will test a spot a few feet further up and see if I get any power.

 

Next option would be to test the transmission one? Anyone know where the switch is located on a 13 speed?

 

Thanks

Jason

If I remember correctly from my rats nest cleanup, one is the reverse light power and the other is nothing, it's a standard plug for light modules.

 

Alan

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Switch is at the bottom of the shift tower but on the backside of the rear support spring.

 

 

Thanks!

 

I tested that one the other day and wanted to make sure it was the right one.

 

With truck off and truck in reverse, I am getting about 8volts through it.

 

When I pull the switch, and jumper it with a paper clip or wire, I loose power to it.

 

I am guessing it is grounding out somewhere from there?

 

Would it be possible to cut the one that has no voltage and run a wire from that to the rearend incase the original one has a broken wire somewhere else in it? Or is it teed into the wiring harness more after it leaves the tranny?

 

 

So when the reverse is engaged, the wire transfers the voltage to the lights?

 

Batteries are all charged and all fuses are good. I pulled all the fuses in the truck one by one and inspected.

 

Thanks

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  • 1 month later...

A local shop worked the whole day on it a few days ago (only charged me for 2.5 hrs), They were confused by what was going on with it.. They could get 11.2v at the switch, soon as it is crossed over, it died out.. They ended up swapping out the switch and still same.. They ran a new line to the fuse panel, down to the switch and back to the lights.. It got them working but still have the LCM error.. They think the LCM is shorted out.. I am hoping a volvo dealer can disable that perimeter for the reverse lights to get rid of the annoying warning message when starting..

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