306 XSi intermittent speedo

[franster]

Basically the speedo on my 306 XSi only works when it feels like it. I had thought it may be the speed sensor, but when I was sitting in traffic the other day, the needle began to hover at around 10mph even though the car was not moving. I'm now more prone to think it might be a faulty speedo, but would like a bit of advice before I start guessing and buying parts I might not need.

Thanks in advance

[Peter.N.]

Could be a bad connection on the sensor plug, any varying resistance can be interpreted by the speedo as pulses. Is the mileometer working, if yes then it probably will be the instrument but if not more likely a signal path problem.

Peter

[franster]

Mileometer only works when speedo does, which is why I initially thought it was the speed sensor. I'll try and trace the wires and clean up connections as a first point of call.

Is the speed sensor on the back of the gearbox, near the driveshaft output?

[citronut]

Is the speed sensor on the back of the gearbox, near the driveshaft output?

yes the transducer fits were a speedo cable would normally plug into the diff casing just above the O/S drive shaft outlet,

and the wiring connector plugs straight onto the top of that

[franster]

Checked and cleaned the connections on the speed sensor and refitted. Still the same!

Any more ideas? Would the sensor itself work intermittently, and give false signals at standstill? Do I need to be tracing wires looking for frayed bits shorting to earth? Should I just leave it and put up with it? AAAARRRRGHH!

[citronut]

Any more ideas? Would the sensor itself work intermittently, and give false signals at standstill? Do I need to be tracing wires looking for frayed bits shorting to earth? Should I just leave it and put up with it? AAAARRRRGHH!

yes it is possible,

i have seen a transducer full of gear oil as the spindle O ring had failed, i took it apart cleaned it out and refitted it, then it worked fine fa quite a few thousand miles, the car went to meet its maker before i saw the cleaned transducer fail again

[franster]

Any more ideas? Would the sensor itself work intermittently, and give false signals at standstill? Do I need to be tracing wires looking for frayed bits shorting to earth? Should I just leave it and put up with it? AAAARRRRGHH!

yes it is possible,

i have seen a transducer full of gear oil as the spindle O ring had failed, i took it apart cleaned it out and refitted it, then it worked fine fa quite a few thousand miles, the car went to meet its maker before i saw the cleaned transducer fail again

Thanks. I'll give that a go.