Rear tail light not working after towing converter installed

[ohemby]

I had a towing converter installed recently and while towing a trailer the "position bulb" message started coming up.

Sure enough the right tail light (and the front, orange light on the same side) are no longer working.

I tried replacing the bulb with a new one, but it didn't work. Has anyone run into this before?

[hoonk]

If both the front and rear parking (position) lamps are out on one side - they are fused left and right so look for a blown fuse in the c fusebox, on the left end of the dash, #31 is for the right side. (then look for a reason why the fuse would blow)

[ohemby]

That did the trick. Now to figure out why. It popped while I was towing so maybe I need a different converter.


If both the front and rear parking (position) lamps are out on one side - they are fused left and right so look for a blown fuse in the c fusebox, on the left end of the dash, #31 is for the right side. (then look for a reason why the fuse would blow)

[The Landshark]

I had similar problems with a towing relay that was installed in my '06 by the previous owners. i replaced it with the proper volvo unit, no problems since, trailer light indicators now appear on the dash and as it has the 13 pin socket i have power for my trailers which the old seven pin unit didn't have. Reverse lights are also handy. The parts guy at my local dealer said that the volvo box also tells the dstc system to adjust itself to accommodate a trailer when one is connected.

[ohemby]

That sounds great! Sounds like I'll be doing the same.

Thanks!

[Willy]

7372
The parts guy at my local dealer said that the volvo box also tells the dstc system to adjust itself to accommodate a trailer when one is connected.
I am not sure about that. When I connect a trailer (7 pin, nothing in between them except copper wires :cool:)
the small turn indicators also work. Perhaps the system simply sees a current flow.
Forgive my ignorance, but why is a convertor needed? I assume it has to do with 7 to 13 pins.
Isn't it possible to take a male and female connector, one 7 pin, the other 13 pin and cross-wire
the signals between them instead of using some electronic device (if that is what a convertor is)?
Or altenatively, raplacing the 7 pin connector on the car's side? If I am not mistaken, possibly
starting only from a certain MY, the connector near the spare tire is wired to accept a 13 pin connector.
See pdf for MY2005
Willy
7372

[The Landshark]

7372
I am not sure about that. When I connect a trailer (7 pin, nothing in between them except copper wires :cool:)
the small turn indicators also work. Perhaps the system simply sees a current flow.
Forgive my ignorance, but why is a convertor needed? I assume it has to do with 7 to 13 pins.
Isn't it possible to take a male and female connector, one 7 pin, the other 13 pin and cross-wire
the signals between them instead of using some electronic device (if that is what a convertor is)?
Or altenatively, raplacing the 7 pin connector on the car's side? If I am not mistaken, possibly
starting only from a certain MY, the connector near the spare tire is wired to accept a 13 pin connector.
See pdf for MY2005
Willy
7372

The car came with a relay box wired through the cars own tail lights.
I substituted the volvo module and harness. The seven pin or thirteen pin harnesses both just plug in. Nothing really different about them but the 13 pin has some extra functions like power and reverse lights.
Not too worried about reverse lights but power is useful. Both for the fridge in my caravan and the hydraulic pump in my tipping trailer.
Newer volve modules are supposed to be alright when using led trailer lights. Older ones apparently need a converter.

[Willy]

Some problems with LED's are caused by the very low current, making the system think that the bulb is out.
If so, a shunt resistor may solve that.

[Jacksonfam5]

You have to use a powered towing converter as there is not enough inline power to the converter from the bulb signal wires. Powered one works great in my XC70 though I am on the second one in about 7 years.

[The Landshark]

Some problems with LED's are caused by the very low current, making the system think that the bulb is out.
If so, a shunt resistor may solve that.

The newer volvo module is apparently ok.


You have to use a powered towing converter as there is not enough inline power to the converter from the bulb signal wires. Powered one works great in my XC70 though I am on the second one in about 7 years.

Yes but the canbus doesn't know the trailer is there, i think in our xc's its just the dstc and abs that likes to know if there's a trailer behind, apparently engine and automatic transmission are adjusted in the xc90 as well

[Willy]

You have to use a powered towing converter as there is not enough inline power to the converter from the bulb signal wires.
Do you mean for average power consuming trailer lights?
At least for MY2004 this is not the case, I have been towing a trailer through the years without lighting problems.

[Reverend]

I actually think I have a spare towing module in the garage. Never used. In original blue box.

PM me and I'll dig around in the garage.