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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1073 (Engine Controls Diagnosis - 6.6L (LLY) (DTC P0238 To DTC P0652)) >> Diagnosis >> DTC P0612 >> Diagnostic Aids

Diagnostic Aids

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

If the engine starts, the ignition relay control circuit is shorted to power intermittently.

DTC P0612

Step Action Values Yes No
Schematic Reference:  Engine Controls Schematics 
Connector End View Reference: Engine Control Module (ECM) 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 Attempt to start the engine.
Does the engine start?		 - Go to Diagnostic Aids Go to Step 3 
3
  1. Turn OFF the ignition.
  2. Remove therelay that supplies ignition voltage to the fuel injection control module (FICM) using J 43244  Relay Puller Pliers.
  3. Disconnect the engine control module (ECM) connector containing the relay control circuit.
  4. Turn ON the ignition.
  5. Probe the relay control circuit with a test lamp connected to a good ground. Refer to Troubleshooting with a Test Lamp in Wiring Systems.
Does the test lamp illuminate?		 - Go to Step 5  Go to Step 4 
4 Measure the resistance of the coil circuit of the relay with a DMM.
Does the resistance measure within the specified range?		 60-80 ohm Go to Step 7  Go to Step 6 
5 Repair the short to battery or ignition voltage on the relay control circuit. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 8  -
6 Replace the relay.
Did you complete the replacement?		 - Go to Step 8  -
7 Replace the ECM. Refer to Engine Control Module (ECM) Replacement .
Did you complete the replacement?		 - Go to Step 8  -
8
  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 9 
9 Observe the Capture Info with a scan tool.
Are there any DTCs that have not been diagnosed?		 - Go to Diagnostic Trouble Code (DTC) List System OK
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