Accidentally short-circuited my tach meter. Please help

Hello,

While reinstalling my motometer (including MFA) from a VW Golf MK1 Cab 93, I accidentally touched the circled area while the car was running. I felt electricity on my finger and I instantly saw my rev meter falling to zero.



I took it out again, checked continuity from pin 5 to the connector, checked the 14v to 10v 3pin regulator as described in this forum, I checked earth, all is good.

Symptoms are the following:

• Tach meter does not work (stays at zero)
• MFA Rev meter also shows zero, when doing the key on-off-on procedure to access the "hidden menu".
• MFA AVG lt/100km does not work as well
• The rest all work fine.

Below is a pic of the car running, with lt/100km and rev meter not working


Any help would be greatly appreciated.
Cheers,
 

It is unfortunate I didn't get any responses. So I will share my current progress and maybe you can guide me because I am not good with electrical diagrams.

All the continuity of the 4-pin connector to the tach meter is fine. They go to 12v(pin 14), ground (pin 2), red/black cable (pin 5) comming from the engine bay, and the fourth pin is also well attached.

The question is: Signal to the RED/BLACK cable comes from Digifant ecu or from the igmition coil? On Haynes manual is on diagram 97-9190, the G5 index.

The tach has 3 inputs, one 12VB+ one earth, and the signal is red / black  which is from the ignition coil, it also feeds the fuel pump relay on sircuit path 1, so I suspect that you have burned out your tach.

thanks for the reply. Is there a way to test it out of the car? I will take it apart and try to debug, but how do i test? what should I feed to imitate the red/black input?

You would need a sign-wave or chopped wave signal generator I would imagine as it is the pulsing wave of the various cylinders firing of the coil that produces the signal.  

Never took one apart.