2.0 Turbo Rev Counter Stopped Working

[pugdamo 111 2 Cars]

Iv recently put my 2.0 turbo 309 on the road,i did about 300 miles with no trouble then one day i was on the dual carraigeway,i noticed the rev counter was dropping down to zero then popping back up to 3500rpm it did this for about 5 minuites before dropping off all together,now all i get from the rev counter is everytime i start the car from cold the rev counter briefly flicks up then stays at zero.

I have used the diode method to get the rev counter working,im a bit lost on how to fault find it,any advice greatly recieved.

[Slo 283 1 Cars]

How have you connected the diode mod? Did you buy one pre made or did you fathom your own up? Is it soldered into place? Can you remove it to test the diodes? Probably just a diode popped.

Edited December 3, 2013 by Slo

[pugdamo 111 2 Cars]

I used the wiring diagram from on here,2 diodes on the coil triggers,these go off to earth through a 1k resistor,then the wire that goes up to the tacho has a zener diode in it.

I made my own loom up and its all soldered together,im guessing its the zener that has popped but wanted a way to test it,

[Slo 283 1 Cars]

Get ya multimeter on it easy peasy depending on how well you've hidden it in the wiring looms.

[pugdamo 111 2 Cars]

only just realised i havnt posted that i had cured this,one of the legs on the zener diode had broke,where it was taped to the loom it was on a bend and had just broke,fitted a new zener made sure it was nice and straight when it was secured to the loom and has been fine for over a year