1976 C3 Tachometer

[8DJA]

Hi,
I’m having issue with my 1976 C3 tachometer.

Should I be getting power to the pink wire?
I have tested with a multimeter and the black earth cable is fine, I get 12v on the brown wire which increases to 13 or 14v when I start the engine but nothing on the pink wire.

Thanks

 

[teamzr1]

The brown wire is the TAC output from engine bay to meter
Yes you need to follow that pink wire as it is the 12 volts needed for TAC

Most common failure is the TAC filter in engine bay or the electronics board bolted to the back side of TAC
You can buy replacement for that board

 

[8DJA]

I have checked the brown wire via a continuity test and that does go to the tach filter.
Any idea where the pink wire goes to so can test continuity between both ends.

 

[teamzr1]

The Ign switch feeds 12 volts to several functions
You need to follow the pink wire from that switch to where it connects to several pink wires, one is to the TAC

 

[teamzr1]

Should be easy to debug as many pinks connect together and if the others connected there work than the pink
from TAC to the multi connection point is a problem

 

[8DJA]

Thanks, I will have a look to see if I can fine the wire.
I’m wondering if that wire might be an issue as don’t think the other gauges are working either. I checked the fuse and that seems fine but needs a bit more investigating.

This is a restoration so just finding the issues as I go.

 

[teamzr1]

If the fuses are good and most or all dash not working than must find from ign switch to the place all the pink wires are spliced together

 

[Emc]

Simple You will have a bad tach board end of

 

[teamzr1]

Without 12 volts and also stating other gauges do not work, and they all are on the same pink circuit
there is no way knowing the tach gauge also has a circuits board problem

Must debug where all those gauge pink wires are connected to pink wire going to ign switch

 

[8DJA]

Issue now sorted by a new tach board.
Old one looks like it was shorting the positive and negative connections across it.