Originally Posted by
JOHNDQ
Ok two whites are the heater, one will be a earth the other a 12v feed! If the black is the signal don't prope into it, the grey will be the earth for the sensor! If you are getting only 4 volts you must have a wiring fault! Do a voltage drop test, put muti meter reading volts onto the 4volt wire then to battery live it should read 8volts (4v+8v=12v) this would show you have a "voltage drop"
Ok so both the white ones should be 12v as they are the heater wires, sorry you say put the meter to volts then on the 4v (use the red lead of the multimeter) then the other lead (of the multimeter black) to the battery live? If they are both lives (positives) I won't get a reading as there is no earth involved, ? Or am I missing something? Thanks again for the reply.