Rev Counter Not Working

[carlos85]

I know this has prob been asked before. I've read something on here about the coil pack controling the rev counter, is this true? i've had a look and there is some plugs missing from the pack (i.e. not plugged in). Could this be why they are not working?

[rubjonny]

rev counter comes from the red/black wire on coil, most mk2s have 1 spade plug on block wire side of coil spare, has what looks liek a snapped off plug on it, but its actually there to prevent you shorting anything out on that terminal as its ignition live.

[carlos85]

this is what it looks like

[squires]

http://www.golfgtiforum.co.uk/index.php?topic=112983.0

presuming yours is 90 spec, to get mine working i just unplugged fuse 21 a refitted anfter a few seconds.

[carlos85]

i've done that as the clock is working

[rubjonny]

yeah that is correct carlos, the front spade is unused on most mk2s, though you should have that p'snapped plug' i mentioned. not the end of the world though, just means be carefull when messin around in that area you dont short it!
to test if the rev signal is getting to clocks, disconnect the yellow wire from the big white sensor on top of the oil filter housing, then rev the engine over 2krpm. the oil light and buzzer should sound. if they do the rev signal is getting to the clocks but the rev counter is dead. if it makes no noise then either the rev signal wire is snapped, or there is damage inside the clocks that is stoppign the signal getting to both the rev counter and the oil pressure warnign circuit.

[carlos85]

i'll give that ago

when i got the car it was fitted with mk3 clocks & i think the rev counter was working on them. I've since changed the dash wiring and the speedo cable.

[rubjonny]

ah that could explain it, is it still runnign mk3 clocks? if not you'll need to check behind the fusebox, the mk3 clocks wont work with the mk2 rev counter signal, you have to splice it to pin 7 of the TCI-H unit.  My guess is there is some splicing behind the dash and this is why the mk2 clocks arnt working

[carlos85]

i took the mk3 clocks out for mk2 single pin ones. I've changed the loom, so it's all mk2 instead of mk3. The only thing is that the mk3 had an electric speedo that i changed, but the plug is still part of the engine loom.

[rubjonny]

ok, im thinking either clocks are bust or there is still a bit of dody loom behind the fusebox, have a look at the TCI-H unit check to see if it has any wires spliced into pin 7!