Golf Mk5 Tow Bars - Q&A - All you need to know Guide!! Advice, Tips...

[nc35]

Richard.

You need a multiplex bypass relay. The exact instructions are in the research thread which is link to from the how to guide.

Hi Richard

Can you please post a link for us less able

Cheers

Lee

[richard@thebrae]

Link for multiple bypass relay:- http://www.towingelectrics.com/relays_bypass.php

If you need help to get at the wiring just ask.
The reversing wire is easy to get at over the rear nearside wheel arch, howto is posted on hear,If you do need diags , PM me with an email adress that will accept attachements. Good Luck

[nc35]

Link for multiple bypass relay:- http://www.towingelectrics.com/relays_bypass.php

If you need help to get at the wiring just ask.
The reversing wire is easy to get at over the rear nearside wheel arch, howto is posted on hear,If you do need diags , PM me with an email adress that will accept attachements. Good Luck

Just found out the hard way that I can PM - not enough posts

Well can anyone please help????

Spent all afternoon wiring up a Ryder Smart7 Relay.

Haynes manual and a lot of reading on the forums I think the following is correct:

Rear LH as you look at the car from the back:

Indicator - BLACK/WHITE
Tail - GREY/BLACK
Brake & Tail - BLACK/RED

Rear RH

Indicator - BLACK/GREEN
Tail - BLACK/PURPLE
Brake & Tail - GREY/GREEN

Reverse - BLACK/BLUE

Got everyting Scotch Locked and the cable from the towing bracket wired in the other end of the relay, earthed and live feed too.

The reverse from the relay is switching a reversing camera.

Well the reversing camera works, so I have done something right.

The relay clicks for everything, Lights, Brakes, Indicators, reverse and Hazzard Lights.

But nothing on the trailer or a tow board?????

Anyone any idea what I have done wrong?

Going to borrow a multimeter tomorrow. Will this be of any use detecting a current from the relay?

Thank you all again

Lee

[Ben]

yes, the multimeter is a godsend when wiring a relay, i used one when triple checking all the wires.

[j3ggo]

multimeter 4.99 from maplin. worth every penny

[PFJones]

make sure that the white wire from the towbar wire is going to earth and is a good on any bad earths will throw a spanner in the works also check the 12v in a good one and not a time managed one

[skard]

hi everyone

this thread makes for very informative reading.
i was wondering if anyone can shed some light on a problem i had with my golf mk5?

when i purchased the car it had a witter towbar fitted (no idea how long it had been on for). after a few months of ownership (out of dealer and trader warranty), my engine ECU basically packed in and the car wouldn't start, resulting in a very expensive replacement.

i immediately disconnected the 7 wire relay that had been scotchlocked into the rear light cluster.

as obscure as it may sound, is there any logic in my belief that this way of connecting the electrics has damaged the engine ECU? my other car (206 HDi) uses the CAN-VAN multiplexing system so i know all too well how fragile these systems can be, especially when sending voltage pulses down a cable when it may be expecting a data pulse.
however, i am not sure that the golf light cluster is part of the multiplexed network?

my bro in law has a multiplexed astra van with a towbar using a similar relay box, and he recently had a failed ECU.

i would just like to hear what others may think about this as i really hope it doesn't reoccur and would like to pinpoint the causes of the failed ECU.

by the way, the towbar and rear valance with cutout has been removed as has the electrics box so testing it now isn't possible.

many thanks and happy new year,
Davie

[martin1810]

The reason for using a bypass relay, is it bypasses the can-bus system. Power comes from the 12V feed that has been added, so not part of the existing wiring. Connections to lights are only to trigger electronic relays. Current draw is so small the car circuits are not affected. So basically if this type of wiring is installed correctly you cannot harm the can-bus wires or ecu etc. ECU's becomming faulty are fairly rare. Most ecu faults turn out to be bad connections.

[richard@thebrae]

Martin1880 is correct with his reply, the golf lights are on the canbus for bulb failure, and you can take comfort that thousands of bypass relays correctly fitted to vehicles with canbus systems do not give any canbus problems or affect the car management systems.

[skard]

thanks guys, i always thought it was a long shot that the towbar install was at fault. i guess it would have been nice to pinpoint the reason why the ECU packed in as VW offered no insight.

on that note, i have the towbar but no detachable ball (i believe it is witter part ZQ3003 i need) - other than the manufacturer is there anywhere i can get a used one?

thanks