Rpm gauge jumping or reading 0 while driving

[Christopher Smith]

I have a 1999 Ford Explorer V8 5.0 2WD , I'm curious what could cause my rpm gauge to jump around while driving but not affect anything? I already replaced the iac and tps, also everything is stock. Any advice would help?

 

[Rhett]

Possibly a bad ground, or the connector coming loose from the gauge.

 

[Christopher Smith]

Possibly a bad ground, or the connector coming loose from the gauge.

What bad ground could it possibly be?

 

[Rhett]

What bad ground could it possibly be?

Ground for the dash gauges. Corrosion can build up on them. Also I've seen the gauge electrical connectors come loose.

There is also the possibility that you have a problem with the VSS (Veh speed sensor) or some other sensor. I would check for stored codes before I did anything. I'd also check this site or google for a 2nd gen wiring diagram, dash area -- it should tell you what sensor input(s) your 2nd gen tach is using.