Jumping speedometer.

[monte0185]

Question everyone. 1998 k3500. 454 4l80e. Speedometer started acting crazy above 30mph and transmission is shifting all over the place. Unplugged the vss and transmission shifts good. We'll hard but stays in gear at least. Replaced vss and still does the same thing. I know that some of the stepper motors need to be changed on the gauges think this might be the issue? I'm at a loss so any ideas would be great. I have checked all the wiring as well.

[rickpilgrim]

Computer reads the signal before the speedometer so I really don't think stepper motor from what you describe. I know you replaced the vss and checked the wiring visually but I've seen where wire is unhooked from the pin inside the plug a few times. And the replacement vss may be defective also with the low quality parts made these days.

[monte0185]

I'll check the pins again just to be sure. I did find the ground from body to frame was broke yesterday. Looks like it's been broke for awhile so I doubt that's it. I also read a few post where the ignition switch under the key went bad causing these kids of issues. Something else to try I guess. I also thought about pulling the plug from the sensor hole in the trans itself and putting a vss there to see if maybe my reluctor ring might be bad.