1991 740 speedometer started bouncing around then stopped working. Odometer does not work either. Every now and then the speedometer will jump. Does anyone have any advice? Is something loose? Do I have to take apart the dash?

My 240 wagon has a functioning speedo but non-functioning odometer. I've been told that if I send the speedometer out to a repair facility see eBay or speedometer.com or a local shop that for about $150 I can get the unit repaired. I've also read in an old copy of Rolling that the problem is the plastic gears on the side of the unit which transfers speedometer info to the odometer. I've had the unit out of the dash, which isn't hard to do since on my version its held in by four screws and wedged between the light switch plate and the additional gauges. The electronic unit has a circuit board with a chip on it and what seems to be two motors one for the speedometer and the other for odometer and trip odometer the gears I'm talking about are on the odometer motor to the side of the speedo motor. I think the board translates the electric impulses from the rear axle counter to the speedo and the odo in a fashion as to goven the speed of the electric motors that drive the gears. Exceptionally complex for an seemingly analog device (the speedometer and odometer). Probably Volvo should've left the design as it originally was, a cable driven off the rear shaft of the transmission by a set of gears into a mechanical speedometer and odometer that was mechanically powered by the turning shaft. If they were going electronic they should've gone to a led display for the instrument like many U.S. automakers did. Then we wouldn't have these problems after 150k or more. We'd have the problem of replacing the LED display when the materials that it consist of decompose from time or electric current being passed through them. 6 or one half a dozen of another?

I would still find another at the junkyard as I found a good one! The speedo guy replaced the capacitors in the old one but still didn't help: He also didn't charge for that service! Good Luck!

Most likely your problem is back at the vehicle speed sensor on the rear end. First check the connection and wires since they are prone to get knocked off or broken over time. If the ABS light has been acting up, that's a sure sign the problem is back there. You could also have a problem with the connector at the back of the speedo head but I would sure check the rear end first. The connector is in the middle of the back of the differntial cover right where the rear torque bar crosses it. Make sure you have the car secure and don't try to jack it up with the tire jack to do this.

Thanks for the advice! The problem turned out to be a broken wire just above the differential. I was able to use a wire nut to connect the split ends. PRoblem fixed in 20 minutes. Thanks again.

Hello, if this helps my speedometer did/does the same thing with the exception that the odometer still works. Whenever the speedometer stops working, I push the odometer reset, and the speedometer starts working again. Obviously, the accumulated miles driven clears each time