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At witts end right now with this speedometer issue. I have verified continuity from the ABS/VSS plug at the rear axle all the way to the speedo. I have swapped in 3 different speedo gauge PSOMs at this point. No change. Mileage lights up, but speedo won’t move.
I pulled the diff cover and everything looks perfect in the diff. Proper teeth on tone ring etc. no teeth issues at all.
The VSS came out of an operational rig where the speedo worked when pulled.
I even have continuity under the dash at the speedo adjustment plug(or whatever you call it). Continuity from the rear ABS is there with the ABS module unplugged as well.
3rd brake light works as do cargo lights. No LEDs anywhere.
only puzzling thing is the dome light only works when the passenger door opens OR I turn the headlight switch to turn it on.
has anyone got any insight? I need a speedo and cruise control.
Codes will only tell you that there is no VSS input to the PCM and you know that already.
Have you tried another speedometer head or just the PSOM?
Have you checked the SPEED INPUT SIGNAL?
Sounds like a gap issue.
You need to check the gap between the VSS and the tone ring.
If the gap is OK it is scope time.
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CHECKING THE SPEED INPUT SIGNAL:
Note: Only wiring harness end of connector is to be probed. Vehicle speed control may be used as a good indicator. If it works normally, then the speedometer module is at least receiving a speed input signal and the wiring and sensor can be assumed to be good.
Connect Digital Multimeter Pin 4 (speed in +) and Pin 5 (speed in -).
Does the voltage increase smoothly and continuously from 0 to approximately 3.5 volts as vehicle speed increases from 0 to 48 km/h (0 to 30 mph)?
Yes
REPLACE the instrument cluster .
No
SERVICE wiring. CHECK for open or shorted wiring.
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MEASURE RABS SENSOR AIR GAP:
Remove Rear Axle Differential Cover.
Measure the shortest distance from the RABS sensor pole piece to the teeth on the reservoir bracket (2C250).
Rotate the axle 60°-90°.
Repeat the second and third steps for a total of five measurements.
Are all measurements between 0.127mm (0.005 inch) and 1.14mm (0.045 inch) and within 0.254mm (0.010 inch) of each other?
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USING THE SCOPE:
