Speedo not working

[worldnci1]

I have a 1995 2500 6.5 diesel and the Speedo does not work. Found the front ABS sensor wires bas so I replaced both. Speedo still does not work, so I bought the Speed sensor for the tailshaft of the trans and installed it...Still does not work...bought a used speedo from a wrecking yard, installed it and still no speedo??? I also do not have a heater...blower works but defrost will not work and no change in venting from floor to defrost...I think the control unit is bad???
Thanks
:eek:

[More Power]

Youmay need to trace the VSS signal to the PCM to see if the signal is getting that far. It passes through the VSSB before reaching the PCM or instrument panel.

All components in the loop are pretty reliable. Generally, the VSS signal is lost because of wiring damage beneath the vehicle. Has there been any work done in that are?

Jim

[john8662]

Also a possible VSSB failure.

Check for codes on the truck doing the paper clip method (search the forum on how to do that) and see if it has a VSSB fault code 72.

If so, you need a replacement VSSB, if not, it's a wiring fault.

J