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HOMESERVICE MANUALSCHEVROLET2006CHEVY EXPRESS G2500, VAN CARGO, 6.6 2REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT VARIANT/TRIMSECTION 5 (ENGINE CONTROL SYSTEM - 4.3L - TROUBLESHOOTING & DIAGNOSIS)DISTRIBUTOR IGNITION (DI) SYSTEM DIAGNOSISTEST DESCRIPTION
2006 Chevrolet Chevy Express G2500, Van Cargo, 6.6 2

Test Description

2006 Chevrolet Chevy Express G2500, Van Cargo, 6.6 2SECTION Test Description
WARNING: This page is about a different variant/trim than selected.

The numbers below refer to the step numbers on the diagnostic table.

  1. 3:  This step tests for a CKP signal to the PCM.
  2. 4:  This step tests for an internally shorted CMP sensor.
  3. 9:  This step tests for spark output at more than one spark plug wire. The J 26792  Spark Plug Tester requires a minimum of 25,000 volts to operate. See Special Tools .
  4. 10:  This step determines if spark is being delivered to the distributor cap.
  5. 20:  This step tests if the PCM is providing a timing control signal to the ICM.
  6. 21:  This step tests for a basic engine mechanical condition.
Distributor Ignition (DI) System Diagnosis

Step Action Value(s) Yes No
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module (PCM) Connector End Views
1 Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle
2 Test the fuse which supplies the ignition 1 voltage to the ignition coil assembly and the ignition control module (ICM). Refer to Circuit Protection - Fuses .
Is the fuse open?		 - Go to Step 32  Go to Step 3 
3 
  1. Observe the engine speed parameter with a scan tool.
  2. Crank the engine.
Is the engine speed parameter more than the specified value?		 125 RPM Go to Step 9  Go to Step 4 
4 
  1. Turn OFF the ignition.
  2. Disconnect the camshaft position (CMP) sensor electrical connector.
  3. Attempt to start the engine.
Does the engine start and continue to run?		 - Go to Step 26  Go to Step 5 
5
  1. Turn ON the ignition, with the engine OFF.
  2. Measure the voltage of the 12-volt reference circuit of the CMP sensor to a good ground with a DMM. Refer to Measuring Voltage .
Is the voltage equal the specified value?		 B+ Go to Step 6  Go to Step 8 
6
  1. Turn OFF the ignition.
  2. Disconnect the crankshaft position (CKP) sensor electrical connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the 12-volt reference circuit of the CKP sensor to a good ground with a DMM. Refer to Measuring Voltage .
Is the voltage equal the specified value?		 B+ Go to Step 27  Go to Step 7 
7
  1. Turn OFF the ignition.
  2. Test the CKP 12-volt reference circuit for an open or a short to ground. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 50  Go to Step 8 
8
  1. Turn OFF the ignition.
  2. Test the CMP 12-volt reference circuit for an open or a short to ground. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 50  Go to Step 30 
9 
  1. Turn OFF the ignition.
  2. Disconnect a spark plug wire from a spark plug.
  3. Install the J 26792  Spark Tester into the spark plug wire end and attach the clamp end to a good engine ground. See Special Tools .
    IMPORTANT: A few sparks then nothing is considered no spark.
  4. Observe the J 26792  . See Special Tools .
  5. Crank the engine. If there is no spark on one wire, test a second wire.
Does multiple spark events occur on both spark plug wires?		 - Go to Step 31  Go to Step 10 
10 
  1. Disconnect the ignition coil wire from the distributor cap.
  2. Install the J 26792  into the ignition coil wire end and clamp the spark tester to a good engine ground. See Special Tools .
  3. Observe the J 26792  . See Special Tools .
  4. Crank the engine.
Does multiple spark events occur?		 - Go to Step 21  Go to Step 11 
11
  1. Disconnect the ignition coil wire from the ignition coil.
  2. Measure the ignition coil wire resistance.
Is the resistance less than the specified value?		 1,000 ohm/ft Go to Step 12  Go to Step 44 
12
  1. Turn OFF the ignition.
  2. Disconnect the ignition coil electrical connector.
  3. Probe the ignition coil control circuit of the ignition coil with a test lamp that is connected to battery voltage. Refer to Probing Electrical Connectors .
  4. Crank the engine.
Does the test lamp flash while cranking the engine?		 - Go to Step 15  Go to Step 13 
13
  1. Turn OFF the ignition.
  2. Probe the ignition coil control circuit of the ignition coil with a test lamp connected to battery voltage.
Does the test lamp illuminate?		 - Go to Step 14  Go to Step 16 
14
  1. Turn OFF the ignition.
  2. Disconnect the ignition control module (ICM) electrical connector.
  3. Probe the ignition coil control circuit of the ignition coil with a test lamp connected to battery voltage.
Does the test lamp illuminate?		 - Go to Step 40  Go to Step 47 
15
  1. Turn ON the ignition with the engine OFF.
  2. Measure the voltage from the ignition 1 voltage circuit of the ignition coil to a good ground with a DMM.
Is the voltage more than the specified value?		 10 V Go to Step 29  Go to Step 33 
16
  1. Turn OFF the ignition.
  2. Disconnect the ICM electrical connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the ignition coil control circuit of the ignition control module with a test lamp that is connected to a good ground.
Does the test lamp illuminate?		 - Go to Step 39  Go to Step 17 
17
  1. Turn OFF the ignition.
  2. Test the ignition coil control circuit between the ignition coil and the ignition module for an open or a high resistance. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 50  Go to Step 18 
18
  1. Turn ON the ignition, with the engine OFF.
  2. Measure the voltage from the ignition 1 voltage circuit of the ICM to a good ground with a DMM.
Is the voltage more than the specified value?		 10 V Go to Step 19  Go to Step 34 
19 Probe the ground circuit of the ICM with a test lamp that is connected to battery voltage.
Does the test lamp illuminate?		 - Go to Step 20  Go to Step 35 
20 
  1. Measure the voltage from the ignition control (IC) timing control circuit of the ICM to a good ground with a DMM.
  2. Observe the voltage on the DMM.
  3. Crank the engine.
Is the voltage within the specified value?		 1-4 V Go to Step 28  Go to Step 23 
21 
  1. Remove the distributor cap.
  2. Inspect inside the distributor cap for damage or contamination. Refer to Distributor Inspection .
Did you find a condition?		 - Go to Step 46  Go to Step 22 
22
  1. Observe the distributor rotor.
  2. Crank the engine.
Does the distributor rotor rotate when the engine cranks?		 - Go to Step 45  Go to Diagnostic Aids
23
  1. Turn OFF the ignition.
  2. Disconnect the powertrain control module (PCM) electrical connectors.
  3. Test the IC timing control circuit for an open or high resistance. Refer to Testing for Continuity and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 50  Go to Step 24 
24 Probe the IC timing control circuit of the PCM with a test lamp that is connected to battery voltage. Refer to Probing Electrical Connectors .
Does the test lamp illuminate?		 - Go to Step 37  Go to Step 25 
25
  1. Turn ON the ignition, with the engine OFF.
  2. Probe the IC timing control circuit of the PCM with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors .
Does the test lamp illuminate?		 - Go to Step 38  Go to Step 30 
26 Test for an intermittent and for a poor connection at the CMP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 - Go to Step 50  Go to Step 41 
27 Test for an intermittent and for a poor connection at the CKP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 - Go to Step 50  Go to Step 42 
28 Test for an intermittent and for 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 50  Go to Step 47 
29 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 .
Did you find and correct the condition?		 - Go to Step 50  Go to Step 43 
30 Test for an intermittent and for a poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 - Go to Step 50  Go to Step 48 
31 Inspect the spark plugs for damage or contamination. Refer to Spark Plug Replacement and Spark Plug Inspection .
Did you find and correct the condition?		 - Go to Step 50  Go to Testing for Intermittent Conditions and Poor Connections
32 Repair the short to ground in the ignition 1 voltage circuit. Refer to Circuit Testing and Wiring Repairs .
Did you complete the repair?		 - Go to Step 49  -
33 Repair the open or the high resistance in the ignition 1 voltage circuit between the underhood fuse block and the ignition coil. Refer to Wiring Repairs .
Did you complete the repair?		 - Go to Step 50  -
34 Repair the open or the high resistance in the ignition 1 voltage circuit between the underhood fuse block and the ICM.
Did you complete the repair?		 - Go to Step 50  -
35 Repair the open or the high resistance in the ground circuit of the ICM. Refer to Wiring Repairs .
Did you complete the repair?		 - Go to Step 50  -
36 Repair the open or the high resistance in the IC timing control circuit. Refer to Wiring Repairs .
Did you complete the repair?		 - Go to Step 50  -
37 Repair the short to ground in the IC timing control circuit. Refer to Wiring Repairs .
Did you complete the repair?		 - Go to Step 50  -
38 Repair the short to voltage in the IC timing control circuit. Refer to Wiring Repairs .
Did you complete the repair?		 - Go to Step 50  -
39 Repair the short to voltage in the ignition coil control circuit. Refer to Wiring Repairs .
Did you complete the repair?		 - Go to Step 50  -
40 Repair the short to ground in the ignition coil control circuit. Refer to Wiring Repairs .
Did you complete the repair?		 - Go to Step 50  -
41 Replace the CMP sensor. Refer to Camshaft Position (CMP) Sensor Replacement .
Did you complete the replacement?		 - Go to Step 50  -
42 Replace the CKP sensor. Refer to Crankshaft Position (CKP) Sensor Replacement .
Did you complete the replacement?		 - Go to Step 50  -
43 Replace the ignition coil. Refer to Ignition Coil(s) Replacement .
Did you complete the replacement?		 - Go to Step 50  -
44 Replace the ignition coil wire. Refer to Spark Plug Wire Replacement .
Did you complete the replacement?		 - Go to Step 50  -
45 Replace the distributor rotor. Refer to Distributor Overhaul .
Did you complete the replacement?		 - Go to Step 50  -
46 Replace the distributor cap. Refer to Distributor Overhaul .
Did you complete the replacement?		 - Go to Step 50  -
47 Replace the ICM. Refer to Ignition Control Module Replacement .
Did you complete the replacement?		 - Go to Step 50  -
48 Replace the PCM. Refer to Control Module References for replacement, setup, and programming.
Did you complete the replacement?		 - Go to Step 50  -
49 Replace the fuse.
Did you complete the replacement?		 - Go to Step 50  -
50
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle for 5 minutes.
Does the vehicle operate normally with no malfunction indicator lamp (MIL) illumination and no stored DTCs?		 - System OK Go to Diagnostic Trouble Code (DTC) List - Vehicle
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.