LEMON Manuals: Even more car manuals for everyone
Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1849 (Engine Controls And Fuel - 2.2L (L61) - Troubleshooting & Diagnosis) >> Electronic Ignition (EI) System Diagnosis >> Circuit Description

Circuit Description

WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

Each ignition coil supplies secondary voltage to a pair of spark plugs. This is called a waste spark ignition system. The engine control module (ECM) supplies a signal on each of the ignition control (IC) timing control circuits to the ignition control module (ICM). The ICM fires the correct ignition coil at the correct time based on the signals. The ICM detects if cylinder 1 or cylinder 3 is on the compression stroke by sensing the secondary voltage and polarity of each side of the ignition coil. The ICM detects this voltage with sensing circuitry integrated into each ignition coil. The higher voltage is on the compressing cylinder. This is called compression sense ignition. The ICM provides a synthesized cam signal to the ECM based on these inputs. The ECM uses the cam signal to synchronize fuel injection.

This system consists of the following circuits:

Electronic Ignition (EI) System Diagnosis

Step Action Value(s) Yes No
Schematic Reference:  Engine Controls Schematics 
Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views
1 Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle
2
  1. Crank the engine.
  2. Observe the CKP Active Counter on the scan tool.
Does the CKP Active Counter increment?		 - Go to Step 3  Go to Crankshaft Position Sensor System Diagnosis 
3
  1. Turn OFF the ignition.
  2. Remove the fuel pump relay.
  3. Remove the ignition coil housing. Refer to Ignition Coil Housing Replacement .
  4. Install the J 36012-A  (J 43883) Ignition System Diagnostic Harness. See Special Tools .
  5. Install a J 26792  (SA9199Z) Spark Tester on #1 spark plug jumper wire. See Special Tools .
  6. Connect the #4 jumper wire to a good ground.
  7. Connect the other jumper wires from the 2-4 ignition coil to the respective cylinders.
  8. Observe the spark tester.
  9. Crank the engine.
  10. Repeat the procedure for the remaining cylinders
Does the spark tester spark on all cylinders?		 - Go to Step 6  Go to Step 4 
4 Is the no spark condition only present on one cylinder? - Go to Step 16  Go to Step 5 
5 Is the no spark condition only present on companion cylinders 1-4 or 2-3? - Go to Step 12  Go to Step 8 
6 Does the spark tester indicate a bright blue spark on all cylinders? - Go to Step 7  Go to Step 16 
7
  1. Remove the spark plugs.
  2. 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 23 
8
  1. Turn OFF the ignition.
  2. Disconnect the harness connector of the ignition control module (ICM).
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp from the ignition voltage circuit of the ICM to a good ground.
Does the test lamp illuminate?		 - Go to Step 9  Go to Step 19 
9 Connect a test lamp from the ignition voltage circuit to the ground circuit of the ICM.
Does the test lamp illuminate?		 - Go to Step 10  Go to Step 20 
10
  1. Turn OFF the ignition.
  2. Remove the fuse that supplies ignition voltage to the ICM.
  3. Measure the resistance of the ignition voltage circuit of the ICM from the harness connector of the ICM to the fuse.
Is the resistance less than the specified value?		 3 Ω Go to Step 11  Go to Step 21 
11 Measure the resistance of the ground circuit of the ICM from the harness connector of the ICM to a good ground.
Is the resistance less than the specified value?		 3 Ω Go to Step 12  Go to Step 22 
12
  1. Turn OFF the ignition.
  2. Remove the ICM from the ignition coil housing. Refer to Ignition Control Module Replacement .
  3. Connect the harness connector of the ICM.
  4. Confirm that the interconnect is connected to the ICM.
  5. Turn ON the ignition, with the engine OFF.
    6. IMPORTANT: If using a different test lamp, the bulb resistance needs to be 4 ohms or less.
  6. Connect a J 34730-405  Injector Test Lamp (Noid Light) from the ignition voltage circuit at the ICM interconnect to a good ground. See Special Tools . For the circuit identification in the ICM interconnect, refer to Electronic Ignition (EI) System Description .
Does the test lamp illuminate?		 - Go to Step 13  Go to Step 17 
13
  1. Connect a J 34730-405  between the ignition voltage circuit and the ignition control (IC) timing control circuit for the inoperative ignition coil. See Special Tools . For the circuit identification in the ICM interconnect, refer to Electronic Ignition (EI) System Description .
  2. Crank the engine.
Does the test lamp flash?		 - Go to Step 16  Go to Step 14 
14
  1. Leave the J 34730-405  connected between the ignition voltage and the IC timing control circuit for the inoperative ignition coil. See Special Tools .
  2. Turn OFF the ignition.
  3. Disconnect the harness connector of the ICM.
  4. Connect jumper wires from the harness connector of the ICM to the corresponding terminals of the ICM.
  5. Using the jumper wires, exchange the IC timing control circuits of the ICM.
  6. Crank the engine.
Does the test lamp flash?		 - Go to Step 15  Go to Step 17 
15 Test the IC timing control circuit for the affected ignition coil of the ICM for the following conditions:
  • Open
  • Short to voltage
  • Short to ground
  • High resistance

Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 27  Go to Step 18 
16 Test for shorted terminals or a poor connection at the ignition coil housing. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 - Go to Step 27  Go to Step 24 
17 Test for shorted terminals or a poor connection at the ICM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 - Go to Step 27  Go to Step 25 
18 Test for shorted terminals or a poor connection at the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 - Go to Step 27  Go to Step 26 
19 Repair an open or short to ground in the ignition voltage circuit of the ICM. Refer to Wiring Repairs .
Did you complete the repair?		 - Go to Step 27  -
20 Repair an open in the ground circuit of the ICM. Refer to Wiring Repairs .
Did you complete the repair?		 - Go to Step 27  -
21 Repair the high resistance in the ignition voltage circuit of the ICM. Refer to Wiring Repairs .
Did you complete the repair?		 - Go to Step 27  -
22 Repair the high resistance in the ground circuit of the ICM. Refer to Wiring Repairs .
Did you complete the repair?		 - Go to Step 27  -
23 Replace the spark plugs. Refer to Spark Plug Replacement .
Did you complete the replacement?		 - Go to Step 27  -
24 Replace the ignition coil housing. Refer to Ignition Coil Housing Replacement .
Did you complete the replacement?		 - Go to Step 27  -
25 Replace the ICM. Refer to Ignition Control Module Replacement .
Did you complete the replacement?		 - Go to Step 27  -
26 Replace the ECM. Refer to Control Module References for replacement, setup, and programming.
Did you complete the replacement?		 - Go to Step 27  -
27
  1. Turn the ignition OFF for 30 seconds.
  2. Start the engine and operate the vehicle.
  3. Observe the MIL, vehicle performance, and driveability.
Does the vehicle operate normally?		 - System OK Go to Step 3 
scientia non olet · About LEMON Manuals