Not sure how to determine if the VSS or the PSOM is bad. 95 f150 4WD. I have no speedo/odo and i tried a new vss or dss/abs, that didn't do anything. I also tried to re-sadder the psom, that didnt work. so now it still shifts hard and no speedo/odo.grr.

 

Welcome to FTE!

What do you mean by no speedo/odo? Does the odo display show anything at all or is it completely dead? If it's blank, you probably have a fuse blown.

If it shows mileage that never increases, then the quick way to test for VSS signal is pull the cluster out and get the rear axle off the ground. Make sure the truck is in 2WD and let it idle in gear while you use a meter to see if you got a VSS signal coming into the PSOM.

 

You do not have to pull the cluster out. Just check the signal with the meter set to AC.

But first check fuse #8 and #18.

What do you mean by "I also tried to re-sadder the psom"?

Check it here at the RABS plug:


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I think he means re-soldered the PSOM.

 

I will give that a shot. oddly enough the d/s door was sprung and the fender was also dented in. I did check the fuses, but I will check them again

 

yes that is what I meant, I can tell if its the phone or this dumb old army mechanic. Lol

 

[QUOTE=dixie460;14470166]Welcome to FTE!

What do you mean by no speedo/odo? Does the odo display show anything at all or is it completely dead? If it's blank, you probably have a fuse blown.

If it shows mileage that never increases, then the quick way to test for VSS signal is pull the cluster out and get the rear axle off the ground. Make sure the truck is in 2WD and let it idle in gear while you use a meter to see if you got a VSS signal coming into the PSOM.[/QUOT Happy 4th of July, guess what I'll be doing today👍The odometer display is blank and ABS light is also flashing.😕

 

Nothing is common between the RABS module and the PSOM.
Even the grounds are on opposite sides of the truck kick panels.
They are feed by a common signal from the rear VSS but that would not make the Odometer go blank.
It is possible that the PSOM is dragging the signal from the VSS down and making the RABS lamp flash.

 

I apologize, I mistakenly wrote ABS was flashing when I meant that the overdrive light was flashing. Thanks for getting back to me so quickly!

"the more we sweat in peace time, the less we bleed in war time".

 

The overdrive light flashing is normal when you have no information coming from the PSOM to the Computer.

You say you tried another PSOM, did you check to see if you have power and ground to it with the key on?

Also you said that the truck was hit on the drivers side. That is where the wires run from the PSOM to the Speed Control and then on to the computer. If the Gray wire with a Black stripe is shorted to ground you may be burning up the PSOM's as soon as you put the PSOM in and turn on the key.
You need to check and see if these wires are grounded.




The signal train going from the PSOM to the Computer:


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