Circuit Description

WARNING: This page is about a different car, the 2004 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.

The ignition control module (ICM) has independent power and ground circuits. The circuits between the ICM and the powertrain control module (PCM) consists of the following circuits:

The ignition control (IC) timing signal
The IC timing control
The low resolution engine speed signal
The medium resolution engine signal
The camshaft position signal
The low reference

The ICM sends 3X signals to the PCM, and controls the timing advance during engine cranking. The timing advance changes to PCM control after the following actions occur:

The PCM receives the second 3X signal
The PCM applies 5 volts to the ignition control (IC) timing signal circuit.

Electronic Ignition (EI) System Diagnosis

Step	Action	Values	Yes	No
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module (PCM) Connector End Views or Engine Controls Connector End Views
1	Did you perform the Diagnostic System Check-Engine Controls?	-	Go to Step 2	Go to Diagnostic System Check - Engine Controls
2	Observe the Engine Speed parameter with a scan tool. Crank the engine. Does the scan tool indicate RPM is present?	-	Go to Step 3	Go to Crankshaft Position Sensor (CKP) System Diagnosis
3	Observe the Cam Signal Present parameter with a scan tool. Crank the engine. Does the scan tool display Yes?	-	Go to Step 4	Go to Crankshaft Position Sensor (CKP) System Diagnosis
4	Remove the fuel pump relay with the J 43244 Relay Puller Pliers. IMPORTANT: Ensure to ground the companion cylinder of the cylinder being tested. Test for spark at each cylinder with a J 26792 Spark Tester. Did you have spark on all cylinders?	-	Go to Step 5	Go to Step 7
5	Does the spark tester indicate a bright blue spark on all cylinders?	-	Go to Step 6	Go to Step 7
6	Remove the spark plugs. Examine the spark plugs for any abnormal conditions or damage. Refer to Spark Plug Inspection . Are the spark plugs in good condition?	-	System OK	Go to Step 13
7	Turn OFF the ignition. Connect the J 26792 to the spark plug wire of the inoperative cylinder. Switch the inoperative spark plug wire connection with a known good cylinder at the ignition coils. Crank the engine. Do you have spark on the inoperative cylinder?	-	Go to Step 10	Go to Step 8
8	Disconnect the spark plug wires from the inoperative ignition coil. Measure the secondary resistance of the ignition coil. Is the resistance within the specified range?	5,000-8,000 Ω	Go to Step 9	Go to Step 15
9	Remove the inoperative ignition coil. Connect a test lamp between the control circuits of the ignition coil on the ignition control module (ICM). Crank the engine. Does the test lamp turn ON and OFF while the engine is being cranked?	-	Go to Step 11	Go to Step 12
10	Test the spark plug wires for the following: Proper routing and correct firing order-Refer to Ignition System Specifications . Arching to ground Proper resistance-Refer to Ignition System Specifications . IMPORTANT: If carbon tracking or corrosion is detected, replace both components that are affected. Carbon tracking or corrosion Did you find and correct the condition?	-	Go to Step 17	Go to Step 14
11	Test for an intermittent and for a poor connection at the ignition coil. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 17	Go to Step 15
12	Test for an intermittent and for a poor connection at the ICM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 17	Go to Step 16
13	Replace the spark plugs. Refer to Spark Plug Replacement . Did you complete the replacement?	-	Go to Step 17	-
14	Replace the spark plug wires. Refer to Spark Plug Wire Replacement . Did you complete the replacement?	-	Go to Step 17	-
15	Replace the ignition coil. Refer to Ignition Coil(s) Replacement . Did you complete the replacement?	-	Go to Step 17	-
16	Replace the ICM. Refer to Ignition Control Module Replacement . Did you complete the replacement?	-	Go to Step 17	-
17	Turn the ignition OFF for 30 seconds. Start the engine and operate the vehicle. Observe the vehicle performance and driveability. Does the vehicle operate normally?	-	System OK	Go to Step 3