mhuppertz

New wrinkle. Don't know if it's related to the other problems. Maybe my PCM is starting to flake out...
Thoughts??

dodgethis91cmns

odometer go to? from what ive heard its the gears that drive the speedo and odometer. my odo went but my speedo still works

mhuppertz

No odo either. It's done it twice before, but started working after 10 minutes. This time it didn't come back

Dean Snow

pull your speed sensor/reducer off of the gear that it rides on in the transfer case, then stick it back on, some times they decide to slide off and back on then sometimes just off and stay off for good. its worth a try i guess..

haloman

The 91's was laying in the frame a couple of times.

taterfarm

that happens to me from time to time, I just wiggle the wire connections on the sending unit on the transmission and it starts to work again.

wannadiesel

On a stick truck the PCM has nothing to do with the speedo. The VSS is self-powered.

mhuppertz

That can't be right, because the cruise control uses input from the VSS to not allow the speedo to work below 35 MPH right?

Anyway, I looked at it this morning and scared it enough to start working again! I must have a bad ground somewhere.

wannadiesel

The PCM and the speedo both use the VSS output, but the VSS is self-sufficient.

mhuppertz

Oh, I guess you are right. So if my speedo quits but my cruise still works, it's probably the speedo head (or electronics pertaining to the speedo), but if both the speedo and cruise quit, probably the VSS.

I didn't mean to contradict you, but the schematic looked like the VSS goes into the PCM.....

RuralCruiser007

I know with my truck, if I really honk on it the speedo and odometer both cut out. When I look underneath I can see that the speedo sensor has hit the bottom of the floor boards. I know I need to install new motor mounts and more then likely also transmission mounts.

Just something to look into.

wannadiesel

Feel free. I'm not always right.