Anyone know what could cause both the speedometer and techometer needles to bounce down simultaneously? It only happens for a split-second and doesn't feel like it has any effect on the engine.

I just had a new serpentine belt put on. Would that have anything to do with it?

Thanks

 

Is this a 72 Pinto? Some kind of Honda?
(Seriously, it must be 2003+ if it has a serpentine belt.) I think speedometer & tach are both driven by ECU. Not directly from VSS or ignitor like they are in older Accords.

Flaky electrical connection to the instrument cluster? Does it happen with any relationship with bumps in the road?

 

'98 Accord. Service Tech referred to the belt as serpentine belt.

Haven't noticed it in relation to any bumps on the road. I'll check that on my way home tonight before checking the instrument cluster.

 

I think 98 was the first year for the tach to get it's signal from the ECU. Not sure about the speedometer for that year.

Since both go flaky TOGETHER, that suggests something happenning where the signals are physically together. Like the wiring harness at the back of the cluster. Or a bad ground for the cluster.

If I was certain that the speedometer was driven by the ECU, then that could also include the wiring harness plugs at the ECU.

USA Accord? If so, those plugs at the ECU are located in the center stack, passenger side, sorta alongside the passenger's left foot but covered by the carpeting.