4Runner 4.0L V6

A DIS (Direct Ignition System) is used in the 1GR-FE engine. The DIS improves the ignition timing accuracy, reduces high-voltage loss, and enhances the overall reliability of the ignition system by eliminating the distributor. The DIS in this engine is an independent ignition system which has one ignition coil for each cylinder.

Conventional distributor and pick-up coil have been replaced by 2 camshaft position sensors and crankshaft position sensor. Camshaft position sensors are also be referred to as Variable Valve Timing (VVT) sensors. Camshaft position sensors and crankshaft position sensor deliver input signals to ECM. ECM detects standard crankshaft position based on input signals from camshaft position sensors and actual crankshaft position, and engine speed by crankshaft position sensor input signals. Camshaft position sensors are located on each cylinder head valve cover, towards front of engine. Crankshaft position sensor is located at front of crankshaft, near crankshaft pulley. For knock sensor location, see KNOCK SENSOR under ENGINE SENSORS & SWITCHES in REMOVAL & INSTALLATION - V6 & V8 article.

The ECM uses 6 ignition primary control signals to the ignitors for the ignition coils. DIS uses 6 ignition coils with internal ignitors, one ignition coil for each cylinder. See Figure. Cylinder No. 1 is front cylinder on right side of engine when viewed from flywheel end of engine. Cylinder No. 2 is front cylinder on left side of engine when viewed from flywheel end of engine. Cylinders No. 1, 3 and 5 are on right side of engine. Cylinders No. 2, 4 and 6 are on left side of engine. ECM monitors IGF circuit at ignitor to ensure ignition coils have fired.