Flashing Indicator Problem

[Johndouglas]

It's four or five months ago since I fitted my towbar with 12N & 12S wiring on bypass relays. Since then I've done three towed journeys with the first two being uneventful. The last one however wasn't. After hitching on and plugging into the sockets, all the lights worked correctly before moving off. Ten minutes or so into the journey when the n/s indicator was switched, after seven or so clicks the flash rate went into double quick time with the trailer's flashers ceasing to work. Also the car's rear indicator stopped at the same time. Thereafter only the front indicator worked - at double speed. After stopping and switching off the engine, all the lights work again - till next time. During the week on site, the solo car's indicators worked perfectly. I managed to complete my return tow by ensuring that I allowed the indicators to flash no more than four times. My thoughts are that I need a new Smart7 relay, but before I rip out the old one, does anyone else have some ideas. I don't understand why a faulty caravan relay should effect the car's rear flasher.

[coastline taxis]

Yours will have a can bus sysytem on it john. have a bit play with lexia to see if you need to tell it you have a towbar on it

[Johndouglas]

But I thought the whole idea of using bypass relays was so that the car didn't need to know that a trailer was attached.

[coastline taxis]

Not sure but i will check. cant help thinking the ecu will detect that the indicators are using more power than they should and confusing it  Then when you switch the ignition off and back on the ecu resets itself till the next time. See if it does it with the hazzards on

[Johndouglas]

See if it does it with the hazzards on

Once the flashers have gone into their 'funny' mode, they don't work. I've been looking into whether or not the trailer flasher takes power from the canbus system. Apparently it doesn't. The relay has a 12 volt supply direct from the battery. When the flashers are switched, the relay picks up the signal to the lights on the rear of the vehicle and sends its own 12v feed which it has from the battery and so there's no extra load on the canbus. I'm pretty sure my relay is crackered so I have a new one on order.

[Parkesie]

How are the tow bar electrics fitted? A straight plug in fit or the old blue scotch locks of awfulness?

[Johndouglas]

Each light is connected with a Scotchlock.

[Parkesie]

Double check all the connections are good and that the scotch locks havent had ago at completely cutting the wires. If they are all good id suspect a duff relay giving the bsi a ***oops*** fit. If you can id think about doing soldered joints and insulating them properly instead of scotch locks. As a quick fix they do the job but over time if they get knocked or wet they deteriorate or cut the wires and cause no end of trouble.

[Johndouglas]

Yes - scotchlocks do have a reputation for failing but I've never found them so. I've used them for many years, the most recent in 2005 when I got my Mk2 C5. All were still good when I parted with it just a few months ago.

 

But I have a new relay to go in now and if the rain stays off, it should be in by this evening.

[Johndouglas]

A new relay looks as though it's solved the problem.   I've been running the car for a couple of days with a trailer board plugged in and all the rear lights are working as they should.

[Parkesie]

Happy days