I just purchased a 92 940T and the speedo once it reaches 45mph it wont show any faster. It works fine from 0-45 basically. My cruise works fine also.

Ive read about the sensor in the rear diff, is that more than likely the problem ??

Phil:

If you compare the speed at which the odometer ticks the miles when you're driving 45 versus, say 80, does the odometer seem to increase in speed correctly? If the odometer seems to be changing speed accurately with the speed of the car, but the speedometer needle is limited to 45, the culprit is most likely the gauge and not the speed sensor, since the same sensor sends only one signal for both.

I have seen posts before concerning resoldering some sketchy places on the back of the gauge itself. You might check in the 700/900 FAQ to see if some instructions are in there.

Hope the fix goes smoothly.

Guid
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Guid ('92 745 291k, '91 940 SE 294k, '09 CR-V)

Dear Phils94850,

Hope you're well. I'd guess the problem is in the instrument cluster itself. Is the speedometer's needle slightly canted - and so unable to move freely - perhaps as a result of someone being careless, while doing work inside the cluster?

Failures of speed sensors are not common. Yours seems to work consistently, yet you don't get full speed indicated. Most often, sensors stop working entirely, or may work only intermittently. Vibrations, presence of moisture, and/or changes in temperature, etc., can drive intermittancy.

When a sensor works consistently over the full range of normal driving conditions, it likely is in good order.

Thus, I'd try to find a replacement instrument cluster at a salvage yard. Be advised: speedometers from 1995 and later model years will not fit into a 1992 cluster, and such clusters will not fit into a 1992 car (different type of connectors from the wiring harness to the cluster).

Further, if you want to substitute an entire cluster, not just the speedo itself, then you must find a cluster from a 1991 or 1992 car. A gas gauge change in 1993 and later clusters makes these later clusters unsuitable for 1991-92 cars. Specifically, a 1993 cluster's gas gauge will not work at all in a 1991 or 1992 car.

To get the donor car's speedometer mileage adjusted to your car's actual mileage, you'll need to send (or take) it to a shop, that works on auto instruments. I had good results from APT, at www.gaugeguys.com.

Hope this helps.

Yours faithfully,

Spook

Spook, thanks for the reply. The insturment cluster was replaced at 77k miles with this used one. I guess now this one is acting up. The speedo needle moves very smoothly until it reaches 45mph then just sits there if i go any faster. Once i slow down it drop down smoothly.

Dear Phils94850,

Hope you're well. Two speedometer failures is unusual. Did the first unit fail in the same way, i.e., by a failing to register speeds above 45 mph (or some other level)?

Further, when you changed the first failed speedometer, did you change only the instrument, or did you replace the entire cluster?

The flexible circuit cards (blue plastic) may develop cracks in the embedded copper, that carries signal and power to instruments and lights. A crack usually results in intermittent operation, or none at all. Corrosion between the screw heads (that secure the instruments) and the flexible circuit card, can also be a source of intermittent operation.

The failure you describe likely is internal to the speedometer, because it is not intermittent.

If you cannot find a 1991-92 cluster, you might want to have the problem assessed by a speedometer technician.

Hope this helps.

Yours faithfully,

Spook