Mechanics

F150 BOUNCING SPEEDOMETER

1995 Ford F-150

Electrical problem
1995 Ford F150 V8 Two Wheel Drive Automatic 230000 miles

I have 95 ford pickup, and the speedometer is bouncing back and forth. I have changed the speed sensor on the rear end and changed the gear oil and gasket on the rear. But I still have the same problem.
Any suggestings on what to look for now?
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Jrose51956
February 17, 2009.




SPEEDOMETER
Turn ignition on. Go to next step.
Observe odometer. If odometer display is on and digits appear normal, go to next step. If odometer display is not on and/or digits do not appear normal, go to step 6).
Observe odometer. If word ERROR appears, replace speedometer. If word ERROR does not appear, go to next step.
Test-drive vehicle. If odometer accumulates mileage, go to step 9). If odometer does not accumulate mileage, go to next step.
Test-drive vehicle. If indicated speed on speedometer increases with increasing vehicle speed, replace speedometer. If indicated speed does not increase, go to step 8
Inspect fuses. If fuses are okay, go to next step. Replace fuses and repair shorted wires if necessary. If speedometer and odometer still do not operate, go to next step.
Turn ignition on. Backprobe terminals No. 1 and No. 3 of Programmable Speedometer/Odometer Module (PSOM) harness connector, located behind instrument cluster. If battery voltage does not exist, repair appropriate wire from fuse panel. With ignition off, measure resistance between terminal No. 2 and ground. If resistance is greater than one ohm, repair appropriate wire.
Set DVOM to measure AC voltage. Backprobe PSOM terminals No. 4 and 5. Test-drive vehicle. If voltage increases smoothly from zero to approximately 3.5 volts as vehicle accelerates to 30 MPH, replace speedometer. If voltage does not increase as specified, repair speed sensor circuit.
Test-drive vehicle. If indicated speed on speedometer increases with increasing vehicle speed, speedometer is okay. If operation is not as specified, replace speedometer.
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Dave H
Feb 17, 2009.
Also could be the "Exciter Tone Ring." Located inside the rear end. That is what happened to my 1992 F-150.

Tiny
Toplait
Apr 11, 2014.

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