Speedo an rev counter not working since i purchased the vehicle an need help too fix the problem

Low battery voltage can do strange things to the electronics of your vehicle.

There could be several reasons why the rev counter of your 1992 Opel Monza is not working. One possible reason is a faulty instrument cluster. The instrument cluster is responsible for displaying various information, including the speed and RPM of the vehicle. If the instrument cluster is faulty, it may not be able to display the RPM accurately or at all. Another possible reason is a faulty RPM sensor. The RPM sensor is responsible for sending signals to the instrument cluster, which then displays the RPM on the rev counter. If the RPM sensor is faulty, it may not be able to send signals to the instrument cluster, resulting in a non-functional rev counter.

To fix the issue, you can start by checking the instrument cluster and RPM sensor for any signs of damage or wear and tear. If there are no visible signs of damage, you can try resetting the instrument cluster by disconnecting the battery for a few minutes and then reconnecting it. This may help reset any electronic glitches that may be causing the issue.

If resetting the instrument cluster does not work, you may need to replace either the instrument cluster or RPM sensor. It is recommended to take your vehicle to a certified mechanic or dealership to diagnose and fix the issue properly.

In summary, a non-functional rev counter in a 1992 Opel Monza could be caused by a faulty instrument cluster or RPM sensor. Resetting the instrument cluster or replacing either component may help fix the issue.

Riding without a speedo is not legal.
If a speedo is fitted, it must work but if you ride sensibly, I expect you will be OK.
My XLCH 1000 had a rev counter and no speedo.

Have it checked for DTC'S - diagnostic trouble codes . The speedo information comes from the PCM - engine computer . There is a VSS - vehicle speed sensor , which is an input to the PCM . May have a code stored that will point you in the right direction . Most all parts stores will do this for free . How does the truck drive , run , shift etc...?

The speedometer gets its signal from the Vehicle Speed Sensor (VSS). It is usually on the transmission. The RPM gauge is a separate signal, from the engine controls.

The cluster is really a computer module, so what needs is first make sure the signal for this gages are reaching the cluster if they are then the cluster needs repair, if not you may have a defective fuel level sensor and a problem with the vehicle speed sensor. Flip a coin, the sensor issues will be the most costly as the fuel tank must come out for replacement of the level sensor, that runs many hours of labor.

S reg so is this a 1977 built vehicle ,please excuse my ignorance but when i left the Uk T reg was the latest plate so please state the year as i think this may be sensor type and not a cable

vehicle speed sensor at transmission or bad wires/loose connector

It's unlikely you may have a loose instrument cluster connector unless someone was previously working around that area behind it. If no activity before hand then I'm guessing you may have a deteriorating instrument cluster that needs replacing. You can find people selling in ebay (lower price) or directly from the dealer.

My 04 Ford Focus the battery light keeps coming on & going off, have fitted a new alternator belt but it didn't solve the problem. The battery connections are good. Also the rev counter, speedo & mileage clock keep going haywire when the battery light is on. Do you think it is the alternator? Or is it some other common problem?