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Home >> Chevrolet >> 2005 >> Classic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (DTC P0106-P0300) >> Diagnosis >> DTC P0300 >> Test Description
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Test Description

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

  1. 2:  If the actual CKP variation values are not within the learned values, the misfire counters may increment.
DTC P0300

Step Action Values Yes No
1 Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2 
IMPORTANT: You must perform the crankshaft position (CKP) system variation learn procedure before proceeding with this diagnostic table. Refer to CKP System Variation Learn Procedure .
  1. Start the engine.
  2. Allow the engine to idle or operate within the conditions listed in the Freeze Frame/Failure Records.
  3. Monitor all of the Misfire counters with the scan tool.
Are any of the Misfire Current counters incrementing?		 - Go to Step 3  Go to Intermittent Conditions
3 Are any other DTCs set? - Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information Go to Step 4 
4 Can any abnormal engine noise be heard? - Go to Symptoms - Engine Mechanical in Engine Mechanical Go to Step 5 
5
  1. Start and idle the engine.
  2. Compare the manifold absolute pressure (MAP) voltage indicated by the scan tool with the typical scan data. Refer to Scan Tool Data List .
Is the indicated value more than the typical value?		 - Go to DTC P0108  Go to Step 6 
6 Inspect the following components:
Did you find and correct the condition?		 - Go to Step 20  Go to Step 7 
7
  1. Turn OFF the ignition.
  2. Remove the fuel pump relay. Refer to Relay Replacement (Within an Electrical Center) or Relay Replacement (Attached to Wire Harness) in Wiring Systems.
  3. Remove the ignition coil housing assembly, keeping the ignition control (IC) module assembly connected to the harness connector. Refer to Ignition Coil Housing Replacement .
    4. IMPORTANT: Not grounding the IC module housing may cause an erratic spark.
  4. Connect a jumper wire between the top of the IC module and a good ground.
  5. Install the J 36012-A  Ignition System Diagnosis Harness. See Special Tools .
  6. Install a J 26792  Spark Tester on the #1 spark plug jumper wire. See Special Tools .
  7. Ground the #4 spark plug jumper wire. The #4 wire is the companion to #1.
  8. Crank the engine with the remaining spark plug wires connected.
  9. Repeat the above steps by installing the spark tester on #4 and grounding #1. Do the same for the #2 and the #3 spark plugs. Ensure the companion wire is grounded.
Does the spark tester spark on all cylinders?		 - Go to Step 8  Go to Electronic Ignition (EI) System Diagnosis (with Special Tool) or Electronic Ignition (EI) System Diagnosis (Without Special Tool)
8
  1. Remove the spark plug from the cylinder that indicated a misfire. Refer to Spark Plug Replacement .
  2. Inspect the spark plug. Refer to Spark Plug Inspection .
Does the spark plug appear to be OK?		 - Go to Step 9  Go to Step 10 
9
  1. Exchange the suspected spark plug with another cylinder that is operating properly. Refer to Spark Plug Replacement .
  2. Operate the vehicle under the same conditions that the misfire occurred.
Did the misfire move with the spark plug?		 - Go to Step 16  Go to Step 13 
10 Is the spark plug oil or coolant fouled? - Go to Symptoms - Engine Mechanical in Engine Mechanical Go to Step 11 
11 Is the spark plug gas fouled? - Go to Step 14  Go to Step 12 
12 Did the spark plug show any signs of being cracked, worn, or improperly gapped? - Go to Step 15  Go to Step 13 
13 Perform the fuel injector coil test. Refer to Fuel Injector Coil Test .
Did you find and correct the condition?		 - Go to Step 17  Go to Symptoms - Engine Mechanical in Engine Mechanical
14 Perform the fuel system diagnosis. Refer to Fuel System Diagnosis .
Did you find and correct the condition?		 - Go to Step 17  Go to Symptoms - Engine Mechanical in Engine Mechanical
15 Replace or gap the spark plug. Refer to Spark Plug Replacement .
Did you complete the action?		 - Go to Step 17  -
16 Replace the faulty spark plug. Refer to Spark Plug Replacement .
Did you complete the replacement?		 - Go to Step 17  -
17 Was the customer concern the malfunction indicator lamp (MIL) flashing? - Go to Step 18  Go to Step 19 
18
  1. Operate the vehicle at the specified value for 4 minutes.
  2. Operate the vehicle within the Conditions for Running the DTC P0420 as specified in the supporting text. Refer to DTC P0420 .
Does the DTC run and pass?		 2,500 RPM Go to Step 19  Go to DTC P0420
19
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
Did the DTC fail this ignition?		 - Go to Step 2  Go to Step 20 
20 Observe the Capture Info with a scan tool.
Are there any DTCs that have not been diagnosed?		 - Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information System OK
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