Erratic tach

[dan juhasz]

Customer sent me this video showing his tic toc tach jumping all over, looks like the brake warning lamp is going bright and dim also. Any idea what to look into?
file:///var/mobile/Library/SMS/Attachments/86/06/F5702CA7-94FF-4A09-BD77-865E55B219BB/20250806_140926.mp4

 

[HawkRod]

My knee jerk reaction would be to look at dash grounding

 

[dan juhasz]

My knee jerk reaction would be to look at dash grounding

Is the tach grounded separately or does it share a ground with the clock? Or just through mounting?

 

[HawkRod]

Is the tach grounded separately or does it share a ground with the clock? Or just through mounting?

It's been awhile, but I think it is grounded through mounting.