towbar help

[highlander]

Im in the process of wiring in a second tow bar electrics for charging my caravan’s battery and running my fridge when im driving.
I need to connect one of the wires to a wire coming of the alternator that reads an output of zero volts when the ignition is on but not running!
When the engine is then running the output should be 12ish volts +.
Can any one tell me where to connect this wire as im having difficulty locating it with my volt meter???

[nero279]

not off hand but i can check tomorrow if that's any good to ya, i'm pretty sure there will be a pulsed 12v positive on it, which will be 0v until engine is started. I'll find out tomorow if noone else does it first.

[highlander]

That will be great im stuck at the moment i could just wire it to an ignition feed but then i would drain my battery if my ignition was on so im keen to do it the right way.
Jase

[nero279]

Been out with the multimeter to check it, i'm sure there is one on the alternator, but i was struggling to get the multimeter in there properly.

However, there is a thin yellow wire with red markings in the engine bay fuse box - where they all come in on the right hand side, there's 2 sets of connectors, the top left wire of the left hand connector is showing +12v only with the engine running, or the 7.5A charge fuse. I would think either of these could be used as relay triggers for the towbar electrics, and they're a damn sight easier to get to than the back of the alternator.

On the alternator it'd be one of the 3 wires in the multiplug on the back but like i said i was struggling to get the multimeter in there properly.

Hope this is of some help.

[highlander]

Cheers for that I will go and try that with my multimeter and connect up and see how I get on if the battery terminals on my caravan are reading 12v+ I will assume all is ok. Thanks for your help I will let you know how I get on.
Jase