Ignition Timing Reference Sensor

This sensor is located next to the engine RPM speed sensor. It detects the rotation of a pin located 60 degrees BTDC. This sensor sends a signal to the ECU when TDC occurs for number one and number 4 cylinder. The Hall Effect switch, located in the distributor, produces only one signal for each revolution of the distributor. This signal occurs just before TDC of number one cylinder. This signal is used to determine which signal from the ignition timing reference sensor is the actual TDC signal for number one cylinder. DO NOT  rotate distributor to set base timing.