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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1446 (Engine Control System - 4.2L - Troubleshooting & Diagnosis) >> Diagnosis Information & Procedures >> Electronic Ignition (EI) System Diagnosis >> Test Description

Test Description

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The number below refers to the step number on the diagnostic table.

  1. 5:  A few sparks, then nothing is considered no spark.
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 Are DTCs P0335 or P0336 set? - Go to Diagnostic Trouble Code (DTC) List Go to Step 3 
3 Attempt to start the engine.
Does the engine start and run?		 - Go to Step 4  Go to Step 15 
4 Observe the Misfire Current Counters parameter with a scan tool.
Does the scan tool display any Misfire Current Counters incrementing?		 - Go to Step 5  Go to Diagnostic Aids
5 
  1. Remove the ignition coil for the affected cylinder. Refer to Ignition Coil(s) Replacement .
  2. Install the J 26792  Spark Tester to the spark plug boot.
  3. Attach the clamp end of the J 26792  to a good engine ground.
  4. Observe the J 26792  .
  5. Crank the engine.
Does spark jump the tester gap?		 - Go to Step 11  Go to Step 6 
6
  1. Turn OFF the ignition.
  2. Disconnect the ignition coil for the misfiring cylinder.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the battery voltage with a DMM.
  5. Connect a test lamp between the ignition 1 voltage circuit at the harness connector of the affected ignition coil and a good ground. Refer to Probing Electrical Connectors in Wiring Systems.
  6. Measure the voltage from the ignition 1 voltage circuit to a good ground with a DMM. Refer to Measuring Voltage Drop in Wiring Systems.
Is the voltage within 0.50 volt of the specified value?		 B+ Go to Step 7  Go to Step 15 
7 Probe the ignition 1 voltage circuit of the affected ignition coil with a test lamp connected to the ignition coil ground circuit.
Does the test lamp illuminate?		 - Go to Step 8  Go to Step 16 
8
  1. Start the engine.
  2. Measure the DC frequency from the IC control circuit of the respective ignition coil to a good ground.
Does the frequency measure within the specified range?		 2-20 Hz Go to Step 14  Go to Step 9 
9
  1. Turn ON the ignition, with engine OFF.
  2. Measure the voltage from the IC control circuit of the respective ignition coil to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems.
Does the voltage measure more than the specified value?		 1 V Go to Step 17  Go to Step 10 
10 Test the IC control circuit for the following conditions:
  • An open
  • A short to ground
  • High resistance

Refer to Circuit Testing in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 21  Go to Step 13 
11
  1. Exchange the spark plug with a spark plug from a non-misfiring cylinder. Refer to Spark Plug Replacement .
  2. Install the ignition coil.
  3. Start the engine.
Does the scan tool display that the misfire followed that spark plug?		 - Go to Step 20  Go to Step 12 
12 Inspect the insulating spark plug boot and conducting spring for the following conditions:
  • Any contamination
  • Any deterioration
  • Any arching

Did you find and correct the condition?		 - Go to Step 21  Go to Symptoms - Engine Mechanical in Engine Mechanical
13 Test for an intermittent and for a poor connection at the PCM. 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 21  Go to Step 19 
14 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 21  Go to Step 18 
15 Repair the open, high resistance, or short to ground in the ignition 1 voltage circuit. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 21  -
16 Repair the open in the ignition coil ground circuit. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 21  -
17 Repair the short to voltage in the IC control circuit. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 21  -
18 Replace the ignition coil. Refer to Ignition Coil(s) Replacement .
Did you complete the replacement?		 - Go to Step 21  -
19 Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement .
Did you complete the replacement?		 - Go to Step 21  -
20 Replace the spark plug. Refer to Spark Plug Replacement .
Did you complete the replacement?		 - Go to Step 21  -
21 Attempt to start the engine.
Does the engine start and run?		 - Go to Step 22  Go to Step 2 
22
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Let the engine reach operating temperature.
Are there any DTCs that have not been diagnosed?		 - Go to Diagnostic Trouble Code (DTC) List System OK
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