Stock tachometer not right!

[opeltwinturbo]

My stock 87 GN dash tachometer is screwed up. I am looking for some suggestions. With the ignition on and engine not running the stock tach reads 1,000 RPM. At idle (800 on the aftermarket tach) the stock tach reads 5,000. The stock tach goes immediately into the red zone when engine RPM is increased.

Help !!!

 

[03FatBoy]

Casper's can rebuild yours, and the boost gauge as well

 

[ELLISDALLASWE4]

Check and see if the two wires (one is green) with male and female plugs located behind the alternator are plugged into each other. If they are .....unplug these two wires and you tach will work... leave them unplugged....

 

[djj624]

I know this is an old thread but I just picked up a T with the same issue. Are these writes not supposed to be connected?

N6 running Nexus Project X

 

[Turbotre]

I know this is an old thread but I just picked up a T with the same issue. Are these writes not supposed to be connected?

N6 running Nexus Project X

They are not supposed to be connected,one is the fuel pump prime wire,one is tachometer signal .

 

[djj624]

Thanks for the quick reply. I'll check mine later today.

 

[GNVenom]

Common problem with the module:

http://www.installationinstructions.com/FYI/tachboost.pdf

Eventually, they all fail the same way. Genetic defect.