How to wire switch for heated fuel filter?

[Jim-Phillips]

I have seen Andy Cook's post on this but his heated fuel filter is different to mine... I haave attached a pic of my filter - any ideas anyone how I can add a switch to turn it on/off from inside the car?

I have given letters to the 3 wires that look like they control things..

[nero279]

Before i start, i'm not an auto-electrician, or mechanic or anything, all i'm qualified to do is drive...
Take what i say on face value.

Ideally you want to cut into the positive feed and run a new a new wire through one of the grommets in the bulkhead, to centre console or wherever you want your switch to be and back again. Easiest way to do it is to fold the wire in half before you run it then you only got to run it once and cut it where you folded it.

Looking at the picture, i would say A is the earth, so either B/C should be positive. Trace the wires back. Check that A goes to earth. I would hazard a guess that B is the positive and would go to fusebox (probably). And C is probably the one for the warning light on the dash that tells you it's time to drain the water out of the filter. (assuming a 3rd gen has this warning light?). I would recommend checking all this as it is only a guess from the picture. You can either trace all 3 wires back to check them, or test with a multimeter.

It's then just a case of joining the wires up in the engine bay. Taking one of the ends of the positive feed that you just cut, and joining it to one end of one of the new wires. Then the same on the other side of the bit you just cut. And then wiring the switch inside the car.

I would always solder to join the wires and looming tape to insulate them in the engine bay.

Make sure you use wire rated the same as or as close to what is already there. Easiest way is to see watt the fuse for this circuit is rated at and use the next highest rated wire. (ie) if it's a 5 amp fuse, i would use 8amp wire).

Again, i'm not an electrician, most of what i've learnt is by mistakes, either mine, or someone elses.

[andycook]

i used a wiring diagram to suss my wires out.
there were 2 wires to a vaccum switch
and another pair to heater element

i reckon the pair, which has one earthing on shell of unit - are the ones going to heater element - as that was how mine were