Trailer Electrics. Problems when unhooking

May 29, 2010 7 Replies

I have a Grand Cherokee 2004 with a factory fitted towbar and electrical hookup. I tow my Williams horse trailer with no problems, but when I have unplugged the electrical hookup, I use my indicators and they flash at double the speed. You know how they flash when a bulb goes?



I have rectified the problem in the past by making sure the indicators are in use as i unplug, but this doesn't seem to work now.



Maybe if I disconnect the battery or something?



Has anyone got any Ideas?



Thanks



Bruno


are ALL the indicators actually working at double speed? there may be a switch in the socket that disconnects the rears on the car when the trailer plug is inserted.

Yes All the indicators on the Vehicle are flashing at double speed when the trailer has been dixconnected. No signs of a switch in the plug

Also try the flasher relay, the electronics may have be overloaded causing it to fault.

The thing is, as soon as I plug in the trailer, They flash at normal spped again

Faulty combination flasher then. Unplugging it & replugging it may cure it temporarily, IIRC it's integral to the hazard warning switch.

I think car elecronics have got too clever by half. It's probably got "used" to having a trailer and now is confused by not having one. ;-)

Probably a silly idea but have you tried turning the ignition off and then on again to reset the system? Works for my VW when I get silliness in the electrics.

Tim

Bruno formulated the question :

If this has been wired correctly via the CAN-bus - then I would suspect the CAN-bus is becoming confused. It thinks the trailer is still connected and flashing the indicators at double speed to warn you it has noticed a lamp failure on the trailer.

I have just fitted a full tow pack (proper CAN-bus type)on my Rover and its CAN- bus initially became quite confused. Part of the installation process is to disconnect the battery, to get the CAN-bus to notice the new controller module for the trailer is fitted.

Once installed I plugged it into my caravan to test it, found everything worked as it should then unplugged. After which my reversing sensors didn't work. The CAN-bus seeing a trailer connected turns off the reversing sensors, then is supposed to put them back on when you unplug.

Everything went back to normal the next day and has worked absolutely fine since then.

I would be inclined to suggest disconnecting the battery and leaving it off for 30 minutes to reboot the CAN-bus.

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