I read this b4 but dont know where the join is....can someone tell me where it is or pics of it please! VN Commodore Rough Idle Faulty wiring connection. Black wire with Yellow trace - inside the engine bay coming from EFI control unit. Single wire splits off to two wires. Hold wire, squeeze or move wire at join and the engine should increase in idle then settle. In some cases, the engine may stall. Repair connection. The above wires run to the Coolant Temperature Sensor and the Throttle Position Sensor.