Plug in for tach?

[CincinnatiKid]

My tach's been goin in and out for a few days now and it seems to start working again when I hit a bump, I'm fairly positive it's not the cluster, so I'm thinking loose plug wherever it plugs into the motor, but does anybody know where the sensor plugs into?

[rs4pro3]

the tach signal runs threw the c101 plug, and comes from the ecu

[CincinnatiKid]

the tach signal runs threw the c101 plug, and comes from the ecu

so it runs from the cluster to the ecu?

[rs4pro3]

yes via the c101 plug (main round plug that connects the engine harness to the chassis harness). Should be pin #9 it's a black wire