I think the RPM sensor is attached to the gearbox somewhere mate

 

The signal for the tacho comes from the engine ECU.

There are three things that could cause this problem: A defective instrument cluster, a defective engine ECU, or a wiring fault between the two.

The circuit would need further testing to ascertain exactly where the fault lies - it could get expensive to start guessing!

 

if the ecu was defective woudnt it make the car run crap or am i being a numpty!!
the car is running perfectly well with no issues what so ever

also could a diagnostic check show up anything?
and what is the system of diagnostics this one uses its got a white eobd plug but only pins 3to7 12 and 16 are contacts

 

Diagnostics also means using a test meter to manually check the wiring between the two parts involved, and that the correct signal is being sent out by the ECU. TECH2 (the official Vauxhall diagnostic tester) wouldn't help much with this sort of fault, other than carrying out a test of the instrument panel to make sure the motor that drives the tacho needle actually moves.

The ECU can still control the engine without any problems, even if the output to the tacho failed completely.

 

do a pedal test and check no fuses have gone?

 

found if i smack the binnicle the needle goes back to normal!!!!
must be a loose connection at the back, before i pull binnicle out and have a look is there anything i should be aware of

 

UPDATE
ive removed clocks and put them back in and rev needle went round to 7k and stayed there
pulled clocks back out and rev needle went back to under 0k
started engine and needle is still just vibrating occasionaly when i rev it will only go up to 2k even then it stutters on the way up then back down

so does this mean the binnicle is knackered and needs to be replaced
my speedo is 130mph but ive seen others on ebay that are 140+mph and they say they are from the same spec of car,,,1.4 16v manual,,,has mine been changed before i wonder
any help would be appreciated

 

UPDATE

fitted replacement clocks(used) everything working correctly BUT,,,, i have no oil pressure light! anybody got ideas, light illuminated in old clocks

i opened up back casing and cant see any bulbs in the area of where the oil light is is
there something else i should be looking for

 

Strange - all clusters should have the oil pressure light present.

I can't remember if these are a separate bulb or an LED soldered to the circuit board. Was there space for a twist in bulb in the position of the oil pressure light?

 

there is no space for a twist bulb, not even on the old on either
so i guess it must an led in there somewhere