Tow bar electrics

jtaw45 · Feb 26th, 2021, 10:28

Hi, I've recently put a tow bar on my 2008 S80 D5 and the dedicated electrics from Volvo. When I've tested it the brake is triggering the indicator lights on the trailer, not flashing just lit solidly. Is this due to it needing software update from Volvo? Thanks

Ian21401 · Feb 26th, 2021, 19:17

Could be.
Is it a Volvo towing wiring harness or another brand dedicated for Volvo? they are not the same thing.
Some harnesses require a software update some don’t.
Likewise some car’s require a software update and some don’t.
Did you fit it yourself? If installed by someone else, contact them.

Tatsfield · Feb 27th, 2021, 00:36

If it wasn't fitted by Volvo you might have problems. I bought my XC70 from a Volvo dealer under a Selekt warranty and it came with a tow bar. Recently I took it into the dealer for a recall and while there asked them to check why the rear screen demist didn't seem to work. They discovered that the tow bar was not a Volvo item and had been fitted by a cowboy who butchered the rear fusebox for the tow bar electrics. It required rewiring and a new fusebox for which I didn't pay a penny as Volvo said that although the Selekt warranty expired over two years ago, they accepted that they should have discovered the bodged electrics in the pre Selekt inspection and that the car should never have been sold in that condition and they did the work and didn't charge me. Sometime main dealers can be decent traders and are worth doing business with.

A lot of tow bar electrics are bodged so it's worth having it looked at.

Whyman · Feb 27th, 2021, 03:14

Could be as basic as a poor earth on the trailer brakes with the brakes finding an earth through the indicator circuit.

Or it could be LEd lights on the trailer which sometimes the Volvo system does not work well with. It is usually a trailer problem Sargent do a replacement module for Swift caravans to overcome this.

jtaw45 · Mar 1st, 2021, 09:53

Thanks for the responses. It was a genuine Volvo kit. The car needed a software download to enable the trailer module and all works fine now.

Feb 26th, 2021, 10:28	#1
jtaw45 Senior Member Last Online: Feb 13th, 2024 10:42 Join Date: Dec 2004 Location: Hull	Tow bar electrics Hi, I've recently put a tow bar on my 2008 S80 D5 and the dedicated electrics from Volvo. When I've tested it the brake is triggering the indicator lights on the trailer, not flashing just lit solidly. Is this due to it needing software update from Volvo? Thanks

Feb 26th, 2021, 19:17	#2
Ian21401 Premier Member Last Online: Feb 11th, 2023 20:32 Join Date: May 2010 Location: Blyth, Northumberland	Could be. Is it a Volvo towing wiring harness or another brand dedicated for Volvo? they are not the same thing. Some harnesses require a software update some don’t. Likewise some car’s require a software update and some don’t. Did you fit it yourself? If installed by someone else, contact them. __________________ Ian. Since 2005: 1992 Volvo 940 estate 2.0L. Manual. Daily driver and workhorse. Last edited by Ian21401; Feb 26th, 2021 at 19:19. Reason: Add text.

Feb 27th, 2021, 00:36	#3
Tatsfield Premier Member Last Online: Today 10:10 Join Date: Nov 2015 Location: Poole	If it wasn't fitted by Volvo you might have problems. I bought my XC70 from a Volvo dealer under a Selekt warranty and it came with a tow bar. Recently I took it into the dealer for a recall and while there asked them to check why the rear screen demist didn't seem to work. They discovered that the tow bar was not a Volvo item and had been fitted by a cowboy who butchered the rear fusebox for the tow bar electrics. It required rewiring and a new fusebox for which I didn't pay a penny as Volvo said that although the Selekt warranty expired over two years ago, they accepted that they should have discovered the bodged electrics in the pre Selekt inspection and that the car should never have been sold in that condition and they did the work and didn't charge me. Sometime main dealers can be decent traders and are worth doing business with. A lot of tow bar electrics are bodged so it's worth having it looked at. __________________ 2012 XC70 SE Lux Polestar 230 bhp D5 Auto Oyster Grey

Feb 27th, 2021, 03:14	#4
Whyman Premier Member Last Online: Today 11:10 Join Date: Nov 2013 Location: Newark	Could be as basic as a poor earth on the trailer brakes with the brakes finding an earth through the indicator circuit. Or it could be LEd lights on the trailer which sometimes the Volvo system does not work well with. It is usually a trailer problem Sargent do a replacement module for Swift caravans to overcome this. __________________ XC60 2013 D5 215 SE Lux Nav geartronic

Mar 1st, 2021, 09:53	#5
jtaw45 Senior Member Last Online: Feb 13th, 2024 10:42 Join Date: Dec 2004 Location: Hull	Thanks for the responses. It was a genuine Volvo kit. The car needed a software download to enable the trailer module and all works fine now.

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