Taco meter not working ZX 19D

btwellz · Post by **btwellz** » 03 Jun 2003, 21:54

Hi can any one help. My rev counter in not working at all. I have changed the clocks and still no joy! There are no other problems on the dash just the rev counter. Where should I start. ZX D 1.9 1994.

Post by **Jon** » 03 Jun 2003, 22:03

The rev counter gets its information from a sensor which measures flywheel (engine) speed. The sensor is found in the gearbox bellhousing with a lead coming off it.(black on my car) It is likely that the sensor is either contaminated or broken which would cause this problem.

btwellz · Post by **btwellz** » 03 Jun 2003, 22:22

Thanks for your info.

btwellz · Post by **btwellz** » 04 Jun 2003, 14:20

I have found the wire and all seems to be intact. Is the sensor inside the gearbox bell housing and thus difficult to replace?

Post by **Jon** » 04 Jun 2003, 18:26

OK,
The sensor will have either a grey or a brown connector on the end of the wire. You will find the connector usually in front of the oil filler neck.
N92534 grey connector
N92535 BROWN CONNECTOR
The sensor pickup end is a push fit (inference). Its very difficult to access, and is best done from under the car. Must admit I've never changed one.
Anyone else??

algieuk · Post by **algieuk** » 04 Jun 2003, 21:49

Done them on a BX and a Xantia. Not too hard. They are held in a plastic clip that is secured by one bolt (10mm) screwed through the gearbox mounting flange at the rear of the engine right by the oil level sensor. On a BX it is best to remove the hydraulic pump, but on a Xantia that isn't necessary. It is MUCH easier if you pop the top gear linkage rod off the ball joint. Not a difficult job to do. Takes around 15 minutes on a Xantia. (I am assuming there are no extra "nasty" bits on the turbo as mine was n/a.
There is another sensor in the tdc position on my car but I don't know what that one is for. There is also another connector right by the tacho sensor whcih the pick up will fit into, but that one doens't work the tacho.

btwellz · Post by **btwellz** » 05 Jun 2003, 01:08

Thanks Jon. I can see the push fit connector going into the gear box housing at the rear, once the push fit connector is disconected how is the sensor removed if faulty. I think on looking the sensor may differ from the BX, Xantia but stand corrected.

Dave Burns · Post by **Dave Burns** » 05 Jun 2003, 02:23

The sensor is held in a plastic split clamp, a 10mm headed bolt pinches the clamp shut, gripping the sensor while at the same time securing it to the block.
Loosen the bolt a couple of turns and spread the clamp with a screwdriver, pull the sensor out.
When you refit it, it must be very close to the flywheel, within a few thou or it will not work correctly if at all.
My experience is that the sensor is very long lived, in fact not had to change one yet, but have had to swap a small circuit board on the back of the tacho when it stopped working recently.
You can test the sensor in situ if you have some type of audio equipment that has an auxiliary input, such as a cd input on a car head unit.
When connected it will give an audible signal via the speaker if it is good.
I think you will find that these sensors don't differ for XUD engines, wether it be bx, zx or xantia.
Dave

btwellz · Post by **btwellz** » 05 Jun 2003, 03:06

Thanks all I can now see the light!!!!!!!!!!

Bob Smith · Post by **Bob Smith** » 05 Jun 2003, 13:35

If the sensor is the same as the ones on a BX the resistance will be about 70 ohms. Measuring the voltage output of the sensor alone will not give an accurate answer as a bias current is required and is provided by the 'clock'
Bob

algieuk · Post by **algieuk** » 05 Jun 2003, 13:43

I put a BX sensor on my Xantia, and it worked fine, but you have to change the connector.