tachometer not working

icelandic · Post by **icelandic** » 04 Feb 2011, 14:41

The tachometer in my 95 stopped working. Sometimes it wakes up and workss normally but the working periods are becoming scarcer. I think that what sends the signal to it is the crankcase rpm sensor. However if that is the problem wouldn´t the engine stop working? would´t it trigger a check engine light? Engine is working fine, fuel comsumption is normal. Anyone can shed some light into it? Thanks

FCPEURO · Post by **FCPEURO** » 04 Feb 2011, 17:01

I bet the solder joints on the back of the gauge is wearing out. The car is 16 years old.

icelandic · Post by **icelandic** » 05 Feb 2011, 14:17

It is apparently a very uncommon failure. I do not recall seeing any osimilar on the board.
Do you think it might be the sensor?

Post by **Ozark Lee** » 05 Feb 2011, 17:22

On your '95 you can put the cluster into test mode via OBD port A-7.

Put the flywire into port A-7, key to position II, and press the button 3 times.

The gauge should respond by showing the gas at 1/2 tank, temp to the bottom edge of the red, speedometer needle vertical (12:00) , tachometer vertical (12:00), and the mileage should advance by .5 miles.

To reset out of the test mode just turn the key off and remove the flywire.

That test should help you figure out if the cluster itself is messed up or it is a signal problem.

...Lee

icelandic · Post by **icelandic** » 06 Feb 2011, 04:53

Thanks for the tip, Lee. However I just tryed it. Lead on A-7, Key to position 2, press buttom three times. Nothing happens at the cluster.
Icelandic

Post by **Ozark Lee** » 06 Feb 2011, 06:45

That should work. What happens if you just press the button once?

It could be that the lead is dirty or you may need to adjust the timing between "presses". When entering more than one button push I normally do it at about 3/4 second intervals.

...Lee

Free2drive! · Post by **Free2drive!** » 07 Feb 2011, 16:00

Ozark Lee wrote:On your '95 you can put the cluster into test mode via OBD port A-7.

Put the flywire into port A-7, key to position II, and press the button 3 times.

The gauge should respond by showing the gas at 1/2 tank, temp to the bottom edge of the red, speedometer needle vertical (12:00) , tachometer vertical (12:00), and the mileage should advance by .5 miles.

To reset out of the test mode just turn the key off and remove the flywire.

That test should help you figure out if the cluster itself is messed up or it is a signal problem.

...Lee

Well, my tacho is also messing about. Usually reads 2100 rpm, doesn't raise or lower!! So I am keen to see how the op resolves his issue.

Ozark...I tried your technique above and found the speedo reading 70 mph and the rpm reading 2100 rpm!! Both guages showing a line pointing at 11 am as if on a clock face. The other guages performed the way you explained.

Why does my speedo read 70 mph not straight up, and why is the tacho not working? Am I looking at an earth somewhere or a sensor?

Matt
94 turbo 855 auto.

Post by **Ozark Lee** » 07 Feb 2011, 16:57

Well, my tacho is also messing about. Usually reads 2100 rpm, doesn't raise or lower!! So I am keen to see how the op resolves his issue.

Ozark...I tried your technique above and found the speedo reading 70 mph and the rpm reading 2100 rpm!! Both guages showing a line pointing at 11 am as if on a clock face. The other guages performed the way you explained.

Why does my speedo read 70 mph not straight up, and why is the tacho not working? Am I looking at an earth somewhere or a sensor?

Chances are the zero level on the gauges got messed up when the odometer gear was changed. That part really needs to be added a bit more prominently to the Odometer Gear Tutorial. Before putting the cluster back together the gauges need to be re-zeroed which is done by moving the needle all the way to full scale and then releasing it. It may take several times before it comes to rest at the zero mark on both the speedometer and the tach. At that point the face and the backplane of the cluster can be re-assembled.

Does your tach stay stuck on 2100 even with the key off? If so the needle is just stuck.

...Lee

Free2drive! · Post by **Free2drive!** » 09 Feb 2011, 02:18

Ozark Lee wrote:
Well, my tacho is also messing about. Usually reads 2100 rpm, doesn't raise or lower!! So I am keen to see how the op resolves his issue.

Ozark...I tried your technique above and found the speedo reading 70 mph and the rpm reading 2100 rpm!! Both guages showing a line pointing at 11 am as if on a clock face. The other guages performed the way you explained.

Why does my speedo read 70 mph not straight up, and why is the tacho not working? Am I looking at an earth somewhere or a sensor?
Chances are the zero level on the gauges got messed up when the odometer gear was changed. That part really needs to be added a bit more prominently to the Odometer Gear Tutorial. Before putting the cluster back together the gauges need to be re-zeroed which is done by moving the needle all the way to full scale and then releasing it. It may take several times before it comes to rest at the zero mark on bot the speedometer and the tach. At that point the face and the backplane of the cluster can be re-assembled.

Does your tach stay stuck on 2100 even with the key off? If so the needle is just stuck.

...Lee

Thanks, I will pull out the cluster and strip down as if replacing the odo gear. Do I wind the speedo needle and tacho needle by hand and let go until they rest at zero?
Matt

Post by **Ozark Lee** » 09 Feb 2011, 07:17

Do I wind the speedo needle and tacho needle by hand and let go until they rest at zero?

That is correct.

...Lee