Tach Not working

[jcostarakis]

Ok, so my tach USED to bounce when the battery was low, but has never worked.

Lately, I replaced BOTH of the crank/reference sensors. Now the needle doesn't event jump when the battery is low. I have tested the gauge itself and it does work. (tested by putting into another car!)

Any suggestions?

[curtisr]

Wiser men than I will tell you to clean your grounds, grounds, grounds.

There will be a connection at the coil you can check.

Lastly, it's easy to access the gauges whereupon you can clean the connections with deoxit. Gauges - Removing Late 944 (1985.5 and newer) Gauge Cluster

[DannoXYZ]

Does the car run? If so, speed/ref sensors are fine.

The tach is driven by the DME. Check the wire going through a 4-pin connector between the DME and tach.

[jcostarakis]

Originally Posted by DannoXYZ

Does the car run? If so, speed/ref sensors are fine.

The tach is driven by the DME. Check the wire going through a 4-pin connector between the DME and tach.

Car runs like a scalded dawg!

I will check 4 pin connector at DME tomorrow - Thanks

[jcostarakis]

Originally Posted by curtisr

Wiser men than I will tell you to clean your grounds, grounds, grounds.

There will be a connection at the coil you can check.

Lastly, it's easy to access the gauges whereupon you can clean the connections with deoxit. Gauges - Removing Late 944 (1985.5 and newer) Gauge Cluster

I am sure I have missed a ground..... someplace...... but can check again.

The gauges have been in, and out, a few times - especially when I recovered my dash. That's also when I checked the gauges on another car and found the tach worked,

[911tracker85]

I gave up trying to find the wiring problem on my DE 951 tach. and rarely look at the tach with the shift light flashing telling me when to shift.

had this little tach intended for another purpose.

[jcostarakis]

Originally Posted by 911tracker85

I gave up trying to find the wiring problem on my DE 951 tach. and rarely look at the tach with the shift light flashing telling me when to shift.

had this little tach intended for another purpose.

Its not that I need it, or would even use it per say - just nice that if its in the car, it SHOULD work.

My OCD I guess.....

[DannoXYZ]

If you have scope, check the signal come out of DME #21 a green/black wire. It should be open most of the time with a grounding pulse when the coil is fires. Re-check this signal at the instrument-cluster connector to make sure that the wiring is OK in between.