rev counter goes dead with main beam

hi all i have a c reg 1985 convertable   when i put main beam on the rev counter stops working anyone know why? help needed

When ever there is a fault like that the chances are it is the multi-plug on the back of the speedo,just un-plug it give all the contacts a clean, I use a bit of white spirit on the plug and on the foil,then wipe off afterwards.  
Hope this does the trick.

cheers i,ll give it a try

Also try your earth lead that connects to the rocker cover, I had very similar symptoms and it turned out that the wire had snapped just behind the o crimp that bolts on to the corner of the rocker cover.

cheers for the tips boys did both of these to day and still no joy, the earth lead to the rocker box was cut so i put a direct earth from battery lead to the rocker box but no joy i then took the dash out cleaned the plug terminals up reconected and still the same.  could it be the printed plastic flimsy curciut board behind the speedo/rev counter?????  if not i,m thinking posible main beam switch????? anyone know.   it,s doing my head in, a box of matches is looking good lol

The earth from the rocker corner goes to the coil mounting bracket it earths the dash unit also.

So put it back to the mounting bolt that holds the coil in place.

Have you checked for a blown bulb or loose connection on the headlights them selves.

chortle said

The earth from the rocker corner goes to the coil mounting bracket it earths the dash unit also.

So put it back to the mounting bolt that holds the coil in place.

Have you checked for a blown bulb or loose connection on the headlights them selves.

   ok cheers will try this in the morning hopefully will make the box of matches redundent will report back

look for any brown or brown/white wires to the side of the head, on some mk1s the dash earths here

rubjonny said

look for any brown or brown/white wires to the side of the head, on some mk1s the dash earths here

hi all, not had chance to get out in the garage today hopefully tomorrow many many thank,s for all surgestions i,m sure we,ll get there in the end with all your help hope to report back tomorrow cheers.

worst case tap into the brown wire at the clocks and earth it direct to chassis

sorry for late reply chaps been busy but had a look today and ha presto sorted turned out to be the broken wire going to the rocker box  many thanks for all your help . one down many to go i,ll start a new post as i have a few other probs cheers all