Volvo Repair: Speedometer not working, volvo 740 gl, volvo 740

Question
Dear Sir,

I have a 1989 Volvo 740 GL with near 200K-mile on the engin. I use it everyday fine. About a week ago, the speedometer and mile counter stopped working. I check the instrument cluster and the speedometer sensor cable that are OK. I do not know how to check the sensor and the signal to the speedometer. I also found 12V DC is sent to speedometer on the 4-wire connector for speedometer after ignition swith on. I am really appreciated you can give the detail instructions to troubleshoot.

Thank you


Answer
we have a special tool the can check these signals.I would check the connector at the rear axle speed sensor.ata the speedometer it will be a digital hertz signal.and at the sensor it is a analog sigal.the volvo special tool can check this easily it can provide a speed signal to the speedometer and check the speed signal from the rear axle sensor.if possible I would have the dealer fault trace it with this tool it is easy to do.

Rege