hi does any one no how to test the gear box speed sensor on a 1999 clasic,

 

Yes. Do you have a digital multimeter?

Mind you, if the sensor has failed, you should be getting a check engine light and code 33 error.

If you aren't getting that, likelihood is a fault in the wiring loom between the ECU and instrument pack, or a fault in the instrument pack itself.

If the speedo has stopped working, are the odometer/tripmeter still working as you drive the car?

 

hi i have got the fault 33 an d the odometer/tripmeter are not working ,

 

bttt

 

Sound like it's gone for sure. Also, does the tacho not go beyond 4500rpm?

 

rev counter goes all the way to the red when i reset the ecu but when the engine light comes on it goes in to limp mode.

 

As above if you have code 33 either the sensor's gone or there's a break in the wiring loom. If you already have a new/spare sensor, rather than fitting it into the gearbox immediately, just plug it in to the loom and, with the ignition on, spin the shaft round as quick as you can with your fingers while someone sits in the car watching the speedo needle.

If the speedo nudges upwards in time with you spinning the sensor over you can be pretty confident you found the culprit. If it's still dead, then you need to be checking the continuity in the loom and/or the function of the sensor - but you'll need that multimetr to do either.