The ignition control (IC) module controls spark timing when the engine is cranking. During this Bypass mode of operation, the IC module triggers each ignition coil in the proper sequence at a pre-calibrated timing advance. The IC module is connected directly to the powertrain control module (PCM) and includes the following circuits:

During engine cranking and certain low RPM engine running conditions the IC module controls the ignition timing at a fixed 10 degree advance, this is called bypass mode. When the PCM receives the 3X low resolution engine speed signal from the IC module, 5 volts is applied to the IC timing signal circuit from the PCM. This signals the IC module to allow the IC timing by the PCM. The PCM sends spark timing signals to the IC module on the IC timing control circuit. The PCM monitors the IC timing control circuit for errors.

Inspect the spark plug wires for proper orientation.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Electronic Ignition (EI) System Description

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Special Tools

J 26792 Spark Tester

1. Ignition OFF, remove the fuel pump fuse.
2. Crank the engine and test for a spark on each cylinder spark plug wire using the J 26792 Spark Tester. Ground the companion cylinder spark plug wire of each cylinder when it is tested.

⇒	If a bright blue spark is present on all cylinders, remove and inspect all of the spark plugs for proper torque, proper gap, wear, damage, and fouling. Refer to Spark Plug Inspection. Replace the spark plugs if necessary.

⇒	If spark is present on one or more of the cylinders, inspect and test the spark plug wires for arching, cuts, rubbing on other components, and proper resistance , refer to Spark Plug Wire Inspection or a faulty IC module.

3. Ignition OFF, disconnect the IC module connector. Test for less than 5 ohms between the IC module low reference circuit IC module terminal L and ground.

⇒	If greater than the specified value, test the ground circuit for an open/high resistance.

4. Test for less than 3 ohms between the IC module ground circuit IC module terminal K and battery ground.

⇒	If greater than the specified value, test the ground circuit for an open/high resistance.

5. Ignition ON, test for B+ between the IC module ignition voltage circuit IC module terminal P and ground.

⇒	If less than the specified range, test the IC module ignition voltage circuit for an open/high resistance or short to ground.

6. Connect the IC module.
7. Disconnect the CKP sensor and CMP sensor connectors.
8. Test for less than 1 ohm on each low reference circuit CKP sensor terminal C and CMP sensor terminal B.

⇒	If greater than the specified value, test the low reference circuit for an open/high resistance.

9. Ignition ON, test for more than 10 volts between the 12-volt reference circuit CKP sensor terminal C and CMP sensor terminal C for each sensor and ground.

⇒	If less than the specified range, test the 12-volt reference circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the IC module.

10. Ignition ON, test for 4.0-8.0 volts between each signal circuit CKP sensor  1 terminal B, CKP sensor 2 terminal A, and CMP sensor terminal A and ground.

⇒	If less than the specified range, test the signal circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the IC module.

⇒	If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the IC module.

11. Ignition ON, using a jumper wire connected to ground, momentarily touch each sensor signal circuit CKP sensor 1 terminal B, CKP sensor 2 terminal A and CMP sensor terminal A repeatedly. The CKP Sensor A parameter, CKP Sensor B parameter, and CMP RPM parameter should increment when the appropriate circuit is touched.

⇒	If the CKP Sensor A parameter increments, replace the CKP sensor.

⇒	If the CKP Sensor B parameter increments, replace the CKP sensor.

⇒	If the CMP RPM parameter increments, replace the CMP sensor.

12. Ignition OFF, Disconnect the IC module connector. Ignition ON, using a jumper wire connected to B+, momentarily touch the medium resolution engine speed signal circuit IC module terminal C repeatedly. The CKP Sensor parameter should increment.

⇒	If the CKP Sensor parameter increments, replace the IC module.

⇒	If the CKP Sensor parameter does not increment, test the medium resolution engine speed signal circuit for an open/high resistance, short to ground, or a short to voltage. If all circuits test OK, replace the PCM.

13. Momentarily touch the low resolution engine speed signal circuit IC module terminal D repeatedly. The CKP Sensor parameter should increment.

⇒	If the CKP Sensor parameter increments, replace the IC module.

⇒	If the CKP Sensor parameter does not increment, test the low resolution engine speed signal for an open/high resistance, short to ground, or a short to voltage. If all circuits test OK, replace the PCM.

14. Momentarily touch the camshaft position signal circuit IC module terminal F repeatedly. The CMP RPM parameter should increment.

⇒	If the CMP RPM parameter increments, replace the IC module.

⇒	If the CMP RPM parameter does not increment, test the camshaft position signal circuit for an open/high resistance, short to ground, or a short to voltage. If all circuits test OK, replace the PCM.

15. If all tests are normal, then the system is operating correctly.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.