Ignition Timing Reference Sensor (2.2L Turbo)

Sensor is located next to engine RPM speed sensor and detects rotation of a pin located 460 degrees BTDC. Sensor sends reference signal to control unit when TDC occurs for No. 1 or 4 cylinder.

The Hall Effect switch, located in ignition distributor, produces one signal for each revolution of the distributor. This signal occurs just before TDC of No. 1 cylinder and is used to determine which signal from the ignition timing reference sensor is the actual TDC signal for No. 1 cylinder.