96 obs speedo

[greenthunder7.3]

i have a 96 that has been sitting for a couple years that i got goin again. the speedometer bounces all over. do these trucks have a speed buffer and if so where is it located. i switched out the sensor with one out of another truck and it does the same thing. i checked over the wiring to make sure a mouse has'nt gone crazy and i didn't see anything so just wondering if anyone had any ideas of where to go next.

 

[DieselWrencher]

My 95 F-350 does the same thing. I was looking at a ford wiring schematic and I remember seeing a box of some sort behind the gauge cluster in the diagram. I couldn't find on one my truck and haven't had time to mess with it any more. I just rely on my GPS. LOL

 

[greenthunder7.3]

hm maybe if i get time i'll take the cluster out and see whats goin on behind there.

 

[Tobin]

Yep, they have a PSOM or something like that which buffers the signal from the VSS to the gauge.

Tobin

 

[Casey C]

The PSOM is in the speedometer unit. The spedo head has an input from the VSS and a output with the reshaped signal to the ECM.

 

[greenthunder7.3]

so if that were bad i would have to replace the whole guage unit. i took the unit out and didn't see anything behind it so i just replaced a bunch of burnt out bulbs in it and stuck it back in.