I'm trying to fix intermittent speedo problem. It will at times drop to 0 mph, at which time the odometer, and the trip meter stop functioning as well.
I had the dash out, and inspected. It all looks OK. Sensor on top of diferential was checked, and the wiring connecting to it.
Question I have is, between this sensor, and the speedo itself, is there any break, any additional connection ????

I was recently given a 940 and also had a speedometer problem along with ABS light flashing intermittantly. I was thinking the worst and lots of $$$$ when I first saw a dead speedometer.

Both problems went away after cleaning corrosions (it really didn't look bad at all before cleaning) of the positive battery terminal and the wires connecting to the positive terminal. Also, note that a couple of the wires connected to the terminal were loose.

Try cleaning that post thoroughly!!!!! It very well could be a fast and free repair.

Dear Stan,

Good p.m. and may this find you well. In the 1993 940 (sorry, I don'thave a 1992 wiring diagram) the wires from the speedometer pick-up inthe differential pass through connector C-1, which is at the bottom of the "A" pillar (the one at the windshield). There is also a ground wire, which is affixed to the body, near the driver's door lower hinge.

You should also check the screws, that hold the speedometer to the cluster. If those are loose and/or corroded, it can make for an intermittent connection.

If, after inspecting connector C-1 and the speedometer cluster screws, you find nothing wrong, it would appear that the speedo has failed internally. This happened to me. At first, the cruise control would only engage at 70+ miles/hour. Then the speedo went erratic. Finally, it didn't work at all.

I got a replacement from a salvage yard, send it to APT Instruments in Bloomington, MN (USA). For $60 (includes two-way shipping), they set it to the mileage that was on the car before the speedo broke, plus the distance traveled, after the speedo broke. You'll need to file with them an affidavit, and provide some documentation as to the actual mileage (e.g., a repair bill, that has the mileage noted).

Hope this helps.

Yours faithfully,

jesecon

Thanks very much for responding !
I'm not sure where this C1 connector under pillar "A" is located.
Are you talking about the bunch of wires behind strut tower ?
Sorry for not understanding.
I did however find the ground connection inside the car, to the
left of drivers foot. That one was OK.
I'm not sure if constant 100+ F temps have to do with these failures.
It appears so. I start of fine. Five, ten minutes later it's dead.
Like something overheated....

Dear Stan,

Good p.m. and may this find you well. If this appears to be heat sensitive, it likely is not a connector issue. A corroded connector usually produces wildly intermittent failures, until the corrosion advances to the point, where the circuit is interrupted.

This suggests to me, that the speedometer instrument itself has an internal fault. I'd recommend getting a salvage yard unit, and having it re-set to the correct mileage. APT Instruments in Bloomington, MN, can do this, if you're US-based. You'll need to provide them with some proof of the mileage and complete an affidavit, which likely is available from your State's department of motor vehicles.

Hope this helps.

Yours faithfully,

spook