Component Tests and General Diagnostics

CIRCUIT DESCRIPTION
The Catera 3.0L V6 is equipped with a distributorless ignition system. The ignition system consists of two coil packs, a crankshaft position sensor, and the Engine Control Module (ECM). The ECM performs all of the ignition control module functions. The ignition coil assembly is powered by an ignition feed circuit and also contains a dedicated ground circuit. The remaining three circuits go to the ECM and are the Ignition Control (IC) circuits. The ECM causes a spark to occur by pulsing an IC circuit, which triggers an ignition coil, and fires the appropriate spark plug. The ECM controls the sequencing and the timing.

DIAGNOSTIC AIDS
^ Use the J 35616-A Connector Test Adapter kit for any test that requires probing the ECM harness connector or a component harness connector.
^ Remove the coil pack and inspect for any signs of water intrusion or contamination. Locate the source of water or contamination and repair as necessary.
^ If an ignition misfire is suspected, perform the following procedure:
1. Remove the coil pack.
2. Install the spark tester into the suspected coil.
3. Reconnect the electrical connector.
4. Connect a test lamp to ground.
5. Turn ON the ignition, with the engine OFF.
6. Using the scan tool, operate the suspected coil.
7. While the coil is operating, move the tip of the test lamp around the base, tower, and boot of the suspected coil. Any secondary ignition leakage will arc to the test lamp.
8. Replace the ignition coil pack if any secondary leakage is found.

TEST DESCRIPTION

Steps 1-3:

Steps 4-10:

Steps 11-19:

The numbers below refer to the step numbers on the diagnostic table.
4. The spark tester should show steady, consistent spark across the tip of the spark tester when using the scan tool to operate the coil.
5. This checks the diode in the secondary side of the coil and the continuity of the ground circuit inside the coil. You should be able to read continuity in one direction only.
9. This step is to verify the operation of the ignition coil control circuit and the driver in the ECM.
18. Recheck the system for multiple problems that may be related, for example, fouled spark plugs caused by the fuel system compensating for a misfiring cylinder.