Speedometer is acting funny - 1992 GMC Sierra

Probably replacing the speed sensor on the transmission.Have the codes read, even if the light is not on. Look at the pending codes. The fuel gauge would be the sending unit in the tank. That act funny like that sometimes.

I think both these are electrical on your car. Check wires pluggin to back of cluster, and fuses too.

There may be some loose whires going into your transfer case which will disable the 4x4 light, your speedometer, and cruise control. And if u were in 4wd when a wire became loose then it will stay in 4wd until fixed. Also check any vaccum lines not connected.

The sensors usually are not the problem. You need to replace the cluster or send it to model electronics to have it repaired.

check for cracked air intake tube. just fixed one on 92 accord. also look for bad vacuum lines. check tube right by throttle where it attaches to motor coming from air cleaner box. if so cut it evenly at the crack and reattach using same hose clamp. hope this helps and good luck

From what I have read this sounds like a problem with the second speed sensor located on back at the rear axel on top of the differential. If the cable is loose or the sensor is bad it will cause the brake light to come on and the speedometer to act funny. There are two speed sensors...one in the transmission and the one on the differential. The second one is probably the problem.

Probably a family of squirrels.

speed sensor, probably. if the transmission is acting funny on switching gears when picking up speed. thats what it is...... good luck

Sounds like the cluster is bad. I would try to find one on ebay or a salvage yard.

12 - battery recently disconnected. 21 - Oxygen sensor signal doesn't change (stays at 4.3 - 4.5 V) possibly bad O2 sensor 37 - Transmission temp. sensor reading low.
There are many options that can cause these problems, but loose wiring to the battery and a weak alternator would be one of the first things to check.