HRW electrical problem

i hope somebody can help with this electrical HRW problem, i fitted a hardtop to my mgtf, fitted HRW switch and relay. nothing happens checked for power to the switch. the switch lights up when main lights are on but nothing else. so i checked and replaced the relay, no clicking sound when switch is pressed. but there is power going to the relay. my last point of call was to check if there was any power going to the wiring that connects to the screen , and theres nothing. could it be a fault in the earth ?
i have tried it with the engine running
changed both switch and relay
changed connecting loom that fits to the rear window
checked fuse and replaced
apart from taking all the interior out to check the loom is there something else i could check

I may be following this thread with interest! My HRW kit arrived in the post yesterday, so I'm hoping to try it this weekend! Good luck... :broon:

First thing to know is that the HRW will only work with the engine running.
Secondly, there are more fuses involved than you think.
Third, here's the wiring diagram.

Next thing is:- do you have a mutimeter?
Do you know how to use it?

Yeah , start the engine, put nthe switch ona nd then stick multimeter over the two connections on the window...it should be either -12 or 12 V. Switch etc all light up, relay clicks etc wihty engine off but I don't think the actual heater works when engine is off.

David Aiketgate wrote: First thing to know is that the HRW will only work with the engine running.
Secondly, there are more fuses involved than you think.
Third, here's the wiring diagram.

That is why there is a MGF electrical manual its only £25 :bust:

I've tried to enlarge the wiring diagrams by posting in two sections. It might make them clearer. You need to check all the fuses in the circuitry and then it's a case of checking each wire in turn.