Mk2 Heater Wiring HELP PLEASE

Not 100% on this, but from memory the black wire should be 12v+.
The orange and red (which were not that colour in mine) are grounds. 
One should be a straight ground with very little resistance and another will have a large amount of resistance, this is how the fan runs at different speeds.
Measure both of them and see if what I say checks out but I know on that switch with my 76 mk2 there was 12v grnd and grnd 

Checked all that, no power from black line. Any other ideas?
 

thanks mate, looks to be a later model heater unit than i have.  The same as a mate of mine.  On my heater, there are only two wires coming out, but the red/grey and the orange/black are the same as the loom I have... so thats one thing!
Cheers for your time on this.
 
Alex
 
 

Have had similar probs, with my hacked wiring, some spades, as in your pic looked oxidised, 
i put a little White Zinc Cream on the spades. (from local chemist) removed connector from spade,
with a small artists brush, put some cream into the connector, when replacing connector, wriggled 
the connector sideways (just a little) while pushing slowly onto spade. Prob gone, also fixes bad earth
connections, a dull bulb restored to bright by a scrape to see bare metal on body, a little cream 
applied, connect earth wire and tighten connection, where this has not worked, the hacked wiring 
has been found to be the problem.  Cheers Geoff,     (won't work through paint,  Bare metal Only)