I think I'll have a go at cleaning it !!

Does anyone have any pics so that I know exactly what Im looking for ??

Andy

 

Well I finally sussed the problem this weekend.

I reset the CEL and there appeared to be no problems with the speedo failing or a repeat CEL coming back on. I then turned on my A/C and the speedo immediately dropped to zero.

The only thing I could think of which I had done is connect the yellow box into the speedo signal cable in January. Obviously since then I didn't have any use for A/C so the problem has now only come to my attention.

After testing the 12V to the yellow box the negative connection lost its feed whenever the A/C is switched on. I've now connected the negative to the chassis, problem solved.

Thanks everyone for the input.

Andy