Evening people,after making a new loom up from my speed sensor i need to wire it in somewhere,obviously i can adapt the old connections which i believe to be yellowblue(sensor input) and black(earth) or can i go direct to the screws on the pcb,or... as an option, is it possible to earth the sensor directly to the interior of the car with no ill effects? cheers in advance y`all.p.s thanks for all previous replies certainly helped, now know it not to be the sensor,got to be a dodgy head.

IIRC the speed sensor wire to the back of the clocks is blue/yellow as you have said

 

you can also take an earth of the series of screws on the back of the clocks (pcb) use a multimeter though as a couple of the feeds on the pcb have a +12v feed ;)

Cool,read that part of the wiring diagram correctly then,now i`m assuming that the other wire from the sensor is an earth or negative to complete the circuit, on my 91 uk looks like yellow black but hard to see on the online manual,will check with meter, looking at the rear of the cluster this appears to leave the head via the black wire to body earth so i`m thinking maybe just go direct to a good grounding point.I`m teaching myself all about the components in the pcb at mo, not that mysterious at all..i will cure it ..i will damn it!!