Tow bar fitting affecting start stop

chambersbob · Aug 23rd, 2017, 12:40

I have a V60 D5 and had a towbar fitted (Universal fitting), so should be good for the car! Not a Volvo towbar but a Witter one.
What I do notice is that even without something on the towbar (ie. bike carrier), sometimes my start/stop just disables and becomes unavailable - subsequently the mpg halves. Its been to Volvo and they keep telling me its the towbar affecting the battery, but why should the mpg reduce drastically.
As a reset I pull up and restart the engine, it may take 6 times for it to reset, and then the mpg is as it should be.
It's driving me bonkers!

kenny · Aug 23rd, 2017, 17:27

The make of the towbar sound not make any difference but if you have fitted aftermarket wiring take it out and bin it then fit a genuine Volvo wiring kit and get it programmed by the dealer. Volvo have spent millions designing this car and a trailer kit to match it. The wiring kit does a lot more than make the lights work these days. Your cat knows when it is towing and changes the way it brakes, changes gear and throttle setting to mention a few of the changes. What you fitter has done is fit a kit that is a cheap copy. Even if it is sold as a vehicle specific kit they just aren't as good as the right thing. There are loads of threads on the internet with people having problems after fitting aftermarket trailer kits and dealers are just laughing as it gives them a great escape when you have problems.

Simon Jones · Aug 23rd, 2017, 20:02

I would start by disconnecting the wiring and see if that is at fault. The car monitors the state of the batteries and if the stop/start voltage is low, it will disable the feature. When the wiring was fitted, was the main battery disconnected in accordance with the instructions in the manual which typically suggests waiting 10 mins or so after switching ignition off to ensure all systems are safely shut down.

If your fuel economy has halved it would suggest you must normally spend vast majority of your day sat in stationary traffic. The amount of fuel used when idling is minimal compared to same amount of time.

Aug 23rd, 2017, 12:40	#1
chambersbob New Member Last Online: Aug 23rd, 2017 12:40 Join Date: Aug 2017 Location: DERBY	Tow bar fitting affecting start stop I have a V60 D5 and had a towbar fitted (Universal fitting), so should be good for the car! Not a Volvo towbar but a Witter one. What I do notice is that even without something on the towbar (ie. bike carrier), sometimes my start/stop just disables and becomes unavailable - subsequently the mpg halves. Its been to Volvo and they keep telling me its the towbar affecting the battery, but why should the mpg reduce drastically. As a reset I pull up and restart the engine, it may take 6 times for it to reset, and then the mpg is as it should be. It's driving me bonkers!

Aug 23rd, 2017, 17:27	#2
kenny Master Member Last Online: Dec 16th, 2020 20:33 Join Date: May 2009 Location: kirknewton	The make of the towbar sound not make any difference but if you have fitted aftermarket wiring take it out and bin it then fit a genuine Volvo wiring kit and get it programmed by the dealer. Volvo have spent millions designing this car and a trailer kit to match it. The wiring kit does a lot more than make the lights work these days. Your cat knows when it is towing and changes the way it brakes, changes gear and throttle setting to mention a few of the changes. What you fitter has done is fit a kit that is a cheap copy. Even if it is sold as a vehicle specific kit they just aren't as good as the right thing. There are loads of threads on the internet with people having problems after fitting aftermarket trailer kits and dealers are just laughing as it gives them a great escape when you have problems.

Aug 23rd, 2017, 20:02	#3
Simon Jones Premier Member Last Online: Jan 15th, 2022 11:23 Join Date: Feb 2009 Location: Salisbury (ish)	I would start by disconnecting the wiring and see if that is at fault. The car monitors the state of the batteries and if the stop/start voltage is low, it will disable the feature. When the wiring was fitted, was the main battery disconnected in accordance with the instructions in the manual which typically suggests waiting 10 mins or so after switching ignition off to ensure all systems are safely shut down. If your fuel economy has halved it would suggest you must normally spend vast majority of your day sat in stationary traffic. The amount of fuel used when idling is minimal compared to same amount of time.

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