Hello!  I've been reading the forum for some time now to help inform my recent pruchase of an '08 Octavia Estate Scout...which I'm very happy with!  However, I was seeking some advice regarding the towbar.

 

I bought the car from a dealer some distance away and whilst he was getting it ready (valeting etc) I asked that he got a trade price for fitting a towbar...a normal flange towbar (for me to add a caravan stabiliser and a Witter bike rack adapter) and a detachable towbar.  He emailed me the two options (£240 or £470 +vat respectively) from a local towbar fitter.  When the work was done I had to call the fitting company and pay directly.  When I rang I enquired whether the parking sensors would be switched off etc - which I was told they would be.

 

However, after driving the 100 miles home and reversing into the drive I get a ~3 second beep (the reversing sensor fault beep according to the manual)...and this occurs on the first instance of reversing every time the ignition is switched on.  Plus the car fog light is lit up when connected to a trailer.

 

I have spoken to the towbar company who state that they were simply asked by the dealer for the cheapest options so a dedicated wiring loom (an extra £140) was not fitted.  I did state about my clarification prior to paying but they seemed to gloss over this point.

 

So...I doubt I'll get anywhere with the towbar firm (but I may try again once I get local quotes), but;

 

1.) Can the reversing sensors be deactivated via VAGCOM? 

2.) Can anything be done about the fog light without a dedicated wiring loom?

3.) Can the two innermost reversing sensors be switched off (i.e. those causing the fault beeping due to the presence of the towbar) and the outer two remain on via VAGCOM?

4.) Presumably if 3 is an option I will getting beeping when I am reversing a trailer (I presume that they are only active when in reverse?!)?

5.) Is there anything on the market to narrow the beam of the two central reversing sensors so that they don't see the towbar?

 

I don't tow a lot (maybe a dozen occasions per year - and I think I've only towed once in fog!!), so a little hassle isn't too bad...but it's now a case of minimising that hassle/annoyance for minimal cost!

 

Many thanks and looking forward to the replies!
​Cheers,

Oly

Edited 28 June, 20169 yr by Oly

You certainly need someone with VCDS to scan the car and see what the faults are.

 

Correct wiring and coding of the vehicle will enable and disable certain features when a lighting board is connected - for example, disable parking sensors.

 

Because the towbar installer hasn't used dedicated and specific wiring loom, I suspect they have merely spliced into the existing wiring, and perhaps incorrectly if the fog light is permanently on.

 

In answer to your questions:

 

1) Yes (but could be dependant on correct wiring)

2) Dependant on wiring

3) No, it will be all or nothing

4) If trailer and lighting connected, all the reverse sensors will be disabled

5) I don't believe there is

 

HTH

They will have fitted a bypass relay...

 

This means the car doesn't know when it's towing something so you're stuck with it's current behaviour unless you fit the proper kit. Sorry :(

 

A scan will show any faults with the reverse sensors

Spoke to a car electronics guy today who said to simply find either the sensor control box, or the sounder, and unplug it...simple!!

 

Any downsides? 

 

Does anyone know where in the boot (presumably) they are located?

Edited 28 June, 20169 yr by Oly

Would it be possible to simply physically disconnect the inner two parking sensors so that the system is forced to rely on the outer two sensors only?

Would this work or would the electrics still be looking for the disconnected sensors?

 

I've also found that you can buy fog light cut off relays such as this - http://www.towingelectrics.com/relays_fogcutoff.php

 

In which case would the above disconnection and relay solve all issues?

 

Any advice on how to locate and remove the trim to get at the sensor control unit would be appreciated!

Edited 28 June, 20169 yr by Oly

Don't see why your fudging the car to switch the reverse sensors off. Contact the dealer and get them to fit the dedicated electrics to perform what you had requested or give you are a part refund so you can purchase it and do it yourself.

The dedicated electrics as well as turning off the reverse sensors and fog light it extends the alarm so it goes off if the electrics are disconnected. Also adjusts the traction control and stability programs depending on what you have

I paid the towbar firm directly. It was poor communication that let me down. However we are where we are, so I'm just trying to resolve it as easily as possible.

Apparently a dedicated loom is another ~£140 and still I'd have issues with the reversing sensors picking up the towbar, so there's little to gain.

I presume the fog light cut off relay could also be used to disable the parking sensors when reversing with a trailer connected...

 

 

Apparently a dedicated loom is another ~£140 and still I'd have issues with the reversing sensors picking up the towbar, so there's little to gain. 

 

I have dedicated electrics on mine and no reversing sensor issues when something is connected as it automatically disables them along with the fog light. When nothing is connected to the tow bar then the sensors work as normal and are not triggered by the tow bar itself.

A fog cut off relay is going to cause more problems. Unlike older cars, your Octavia monitors the bulbs so if a fog cut off relay disconnects the fog light, you'll get a bulb warning on your dash.

 

I believe if any single component of the reversing sensor system has problems it disables the entire system. Therefore, if you disconnect the centre sensors or remove the speaker, then none of the sensors will work. You can disconnect the reversing sensor module or find it's fuse which will obviously disable them completely.

 

I'm afraid to say, if you want the correct behaviour you'll need the extra wiring and electrical module. Anything else is a hack and may or may not function correctly.

From what I have read there is nothing that the dedicated loom does to take into account the actual presence of a fixed towbar (although that would be good!). Unless you know differently?

Please also bear in mind that I have a Witter bike rack and caravan stabiliser on the fixed flange towball ... so it is sizeable!

Parking control module is behind boot trim panel on N/S of boot. I have a faulty sensor on mine so just unplugged it. Job done, no sensors

From what I have read there is nothing that the dedicated loom does to take into account the actual presence of a fixed towbar (although that would be good!). Unless you know differently?

Please also bear in mind that I have a Witter bike rack and caravan stabiliser on the fixed flange towball ... so it is sizeable!

 

The dedicated electrics has it's own module in the boot that when activated via VCDS detects when you plug something into the tow bar electrics. This is then displayed on the radio screen and the rear parking sensors and fog light are switched off. 

 

I assume the bike rack is the type that sandwiches between the flange mount and towbar frame in which case it shouldn't trigger the reverse sensors unless you had bikes dangling from it. The bike racks that clamp onto the tow bar ball would trigger the reverse sensors the same as a trailer or caravan would hence but these type have a lighting board built into the them so when plugged into the electrics with a dedicated system the sensors are swtiched off.

The stabiliser again is again usually sandwiched between the flange and tow bar frame so shouldn't trigger any reverse sensor if nothing is connected to it. 

You have assumed right about the towbar fittings, but on occasion the car doesn't go straight to parking sensor error beep and does show an obstruction (i.e. the towbar). As such I'm still unsure as to the benefit of the cost of dedicated electrics...

That fact it occasionally works suggests the towbar fitter may have damaged some wiring or not fully seated one of the connectors. With the towbar in place it should work even if it beeps wildly to show the towbar as an obstruction.

 

If you don't care about parking sensors, unplug the control module. Ignore the fog issue as it'll only become apparent on the rare occurrence of towing in the fog.

 

I believe the dedicated kit should add the following on the FL, not sure about T-ESP on the pre-FL:

- disable fog light when towing

- disable rear sensors when towing

- T-ESP when a suitable ABS pump is fitted (trailer electronic stability program, takes the trailer into account when using ESP)

- bulb monitoring on the trailer/caravan

- alarm will go off when trailer/caravan electrics unplugged

 

None are truly essential but generally nice to have. Only you can decide if it's worth it as you're quite right, the sensors may still detect the towbar when not towing

The car is pre face lift (FL? )

Can anyone direct me as to how to remove the trim to get to the control module? I believe it's on the nearside rear wheel arch?

Many thanks

If you don't have a boot CD player it's easy. Just remove the shopping and the boot net hooks then the side panel should more or less fold down.

 

If you have a boot CD player that might get in the way :/

Unfortunately I do have the boot CD player! And how do the boot hooks come off?

Should be a couple of torx screws, one on each side for the shopping hook, a single one in the middle for the net hook.

 

You might be able to get your arm behind the trim with just the shopping hook removed to unplug the sensors.

That's great thanks. I've figured out how to get to the torx too now!

Is it behind the CD player part or the wheel arch?

I'm just wondering if I can get just one half off if it's not the CD player end!

You can see it in the centre of this picture

 

Thats brilliant many thanks!! Unplugged it and everything seems happy!!

For others reference, I was able to get to it without having to remove the CD player by just working from the other end and folding up the covers. But the covers did need to be loose from the entire side which also requires the removal of the plastic trim around the boot catch.

It requires a little unseen fiddly work but it is possible!

For others reference, I was able to get to it without having to remove the CD player by just working from the other end and folding up the covers. But the covers did need to be loose from the entire side which also requires the removal of the plastic trim around the boot catch.

It requires a little unseen fiddly work but it is possible!

I have recently been thinking about this again and talking to my electrician. 

 

Going back to the start...

1) I viewed the car the first time and the reversing sensors worked fine. We agreed a price including having a towbar fitted. 

 

2) A week later I collecting the car and drove the >2hrs home and notch when reversing into the drive the reversing sensors beeped solid for a couple of seconds before going off. 

 

The towbar has been fitted with a simple PF Jones kit, spliced into the reversing light. At the time I assumed it was because the sensors can constantly see the towbar. As such I just disconnected the sensors brain box and driven the car without the sensors. 

 

However, having recently been thinking about this some more I have taken the sensors out (all are ticking, so working) and even if pointed up at the sky the same fault sound occurs. 

 

I was thinking I have two cheap options (presuming the alternative towbar kit is £££?), to reuse the existing sensors with a cheap retrofit reversing sensor kit off ebay, or install the whole cheap retrofit reversing sensor kit (inc new sensors, although they don't fit the same holes) off ebay. 

 

But recently my electrician suggested it may be a marginally bad earth. The extra cable installed for the towbar may have been enough to drop the voltage enough to cause the fault to occur if the earth isn't great. 

 

Thoughts? Where are the earth points?