Speedo/ABS/VSS info sought

[GVeness]

I am in the process of repowering a 92 Range Rover with a 4.0l SHOC V6 from a 2000 Explorer. I have used most of the Ford running gear and wiring from a wrecked 2 door. The project is just about done, however I am having problems with the speedo. I have used the explorer gauge cluster, and wiring along with the rear mounted VSS. As well I have used the Ford ABS system.

My current problem is that the speedo will not work. I have checked continuinty of the VSS circut from the sensor to the ABS module and to the speedo and it is all good. The ABS light is on. Can anyone tell me what the AC voltage output from the VSS is? and what is the voltage one can expect at the speedo head?

To add anthor twist, I have used a Dana front end from a Jeep Grand Cherokee for the front axle as I did not want to try and engineer the Explorer IFS into the old Rangy. The ABS is picking up signals from the Jeep ABS sensors in the front. Could an incompatibilty between the Jeep speed sensors and the ford ABS unit be a problem?

I'm not real concerned about ABS, but the speedo and related info needs to be there. As yet I have not driven it, only ran it up on stands so I don't know if there is any shift problems as of yet.

 

[bdmaash]

I think the VSS goes from the transmission to the PCM then to the cluster.
You've checked continuity, have you checked for power to the hall effect sensor from the PCM to transmission. You should also be able to trip the sensor with a screwdriver (to see if it works too).

 

[GVeness]

Thanks for the reply. According to the wirng diagram the VSS is conected to the ABS module thence from there the signal is converted from analog to digital then to the speedo head. ( I think). Not sure what you mean by triping the hall effect sensor. As far as I can make out the Hall effect sensor at the differential creates an AC voltage that is then used to tell all the other parts such as PCM, ABS and Speedo what is going on. Oh for the old days......

 

[bdmaash]

The signal is "conditioned" (probably squared up and level shifted) at the PCM then distributed. The signal is a pulse from the abs sensor (can be referred to as AC as you do).
the "tone ring" as it is referred to sometimes is a piece of metal that goes by the "sensor" I refer to. Every time it does that the voltage changes - creating the AC. (0volts to 5volts, no negative voltages like in AC)

If you can measure this, then move onto the next thing in the system.
check the signal output from the PCM to the speedometer.

I suppose if you don't understand how something works, the next best thing is to guess and randomly replace parts.

reading your description, maybe the ABS system does the conditioning and distribution.
1 - makes sure the fuses are ok for the ABS system
2 - make sure the sensors at the wheels get power from the ABS system
3 - make sure the voltage changes when turning the wheel/rotor slowly
4 - make sure the voltage can also be seen changing going to the speedometer