Diagnostic Aids

WARNING: This page is about a different car, the 2003 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

A missing cam pulse to the ECM from the EI module via the CAM signal out circuit will not affect the engine starting. To determine if one of the 2 coils (1/4 or 2/3) is not firing, use scan tool to monitor CALC. COMPRESSION OUTPUT while cranking engine.

If the 1/4 primary or secondary coil or 1/4 control circuit is inoperative, scan tool will display 00000110 or 00001100.
If the 2/3 primary or secondary coil or 2/3 control circuit is inoperative, scan tool will display 00001110 or 00000001.

Engine may or may not start on 2 cylinders. Ignition voltage is supplied to the EI module and passed through the interconnect to the coils. If this circuit is open at the interconnect, neither coil will fire. ENGINE SPEED will indicate correctly, but CALC. COMPRESSION OUTPUT on scan tool will remain at 00000000 when engine is cranking.

Normal CALC. COMPRESSION OUTPUT with engine cranking or running should be 00000110 or 00001001, depending upon camshaft position. If a bit in CALC. COMPRESSION OUTPUT is changing from a 1 to a 0 or vice versa while cranking engine, an ignition problem or compression problem is occurring. Refer to DTC P0300: ENGINE MISFIRE DETECTED in SELF-DIAGNOSTICS - 2.2L VUE article.

Primary ignition coil resistance should be 0.4-1.6 ohms. Secondary ignition coil resistance (tower No. 1 to No. 4 or tower No. 2 to No. 3) should be 3800-5100 ohms.