94 Volvo 960 "No Speed Sensor Code 3-1-1"

[moodyblue426]

Greetings everyone:

For the past few months, the arrow and W and E lights have been flashing and when I read the trouble code, it is always the same - 3-1-1, which states there is no signal for speed sensor. The speedometer seems to register the speed fine and accurately but when this is triggered, I cannot put the car in W mode and it is a much needed feature on a RWD car in winter out here. Any idea what would constantly trigger this code? Could is be a loose connector on the speed sensor? If so, where is the sensor located and is it easily accessible? I also put in a US instrument cluster in MPH a few years back when I brought the car in the US while I was in school. It was originally in KPH only and now has the MPH/KPH style gauge. Could this also trigger that code? Car shifts fine, it isn't a faulty PNP switch (as I had it checked) and the transmission itself is also fine.

Any ideas would be helpful as every time I clear the code, it comes back on when driving or the next day and it is annoying. Is it possible to disable to diagnostic computer completely or would that trigger all of the lights to come on in the dash?

Thanks!

[danr960]

Most likely this is a corrosion problem of a connector, either at the rear differential where the sensor is located, or the big plug on the shock tower driverside under the hood. Try carfully to pry the big plug apart, it is hinged at the bottom, so it comes apart first at the top. Use a electronic/electrical cleaner, like DE-Oxit. Radio shack has it, very expensive, but a little goes a long way. Try cleaning that first, then move on to the connect at the diff.

The pnp switch could be another problem. The cars to '94 have horrible sensor connectors, very prone to corrosion and electrical resistance.

DanR '94 964 391,000 miles (157,000 on the new engine)
'08 S60 T5 84,000 miles