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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1350 (Engine Control System (Troubleshooting & Diagnosis) -- 1.8L (LNK)) >> Troubleshooting >> Fuel Injector Circuit Diagnosis >> Test Description

Test Description

WARNING: This page is about a different car, the 2004 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.

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

  1. 1:  The Diagnostic System Check-Engine Controls prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
  2. 2:  This step checks for fuel injector control signals from the PCM.
  3. 3:  This step checks for a fault that affects all the fuel injectors.
  4. 5:  This step checks for a short in the fuel injector control circuit.
  5. 8:  This step checks for ignition positive voltage.
Fuel Injector Circuit Diagnosis

Step Action Yes No
Schematic Reference:  Engine Controls Schematics 
1  Did you perform the Diagnostic System Check-Engine Controls? Go to Step 2  Go to Diagnostic System Check - Engine Controls
2 
IMPORTANT: This table assumes that the malfunction indicator lamp (MIL) and the data link connector (DLC) function normally. Verify that the MIL operation and the DLC communication are OK before using this table.
  1. Turn OFF the ignition.
  2. Disconnect all 4 fuel injector electrical connectors.
  3. Install a fuel injector test lamp into each fuel injector harness connector.
  4. Observe the injector test lamp for each injector while cranking the engine.
Does the injector test lamp flash for each injector circuit while cranking the engine?		 Go to Fuel Injector Coil Test - Engine Coolant Temperature (ECT) Between 10-35 Degrees C (50-95 Degrees F)  Go to Step 3 
3  Did the fuel injector test lamp flash for at least one fuel injector circuit while cranking the engine? Go to Step 5  Go to Step 4 
4
  1. Check for any of the following conditions:
    • An open in the fuel injector power circuit between the ignition switch and S114.
    • An open in the PCM ground circuits.
  2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.
Is the action complete?		 Go to Step 12  -
5  Was the injector test lamp illuminated steady for any fuel injector circuit? Go to Step 6  Go to Step 8 
6
  1. Turn OFF the ignition.
  2. Install the fuel injector test lamp in any fuel injector circuit that stays ON.
  3. Disconnect PCM electrical connector C1.
  4. Turn ON the ignition, with the engine OFF.
Does the fuel injector test lamp illuminate?		 Go to Step 7  Go to Step 11 
7 Repair the short to ground in the faulty fuel injector control circuit between the PCM and the fuel injector. Refer to Wiring Repairs in Wiring Systems.
Is the action complete?		 Go to Step 12  -
8 
  1. Remove the injector test lamp from the fuel injector electrical connector.
  2. Connect a test lamp from ground to the ignition positive voltage side of the fuel injector harness connector that did not flash.
  3. Turn ON the ignition, with the engine OFF.
Does the test lamp illuminate?		 Go to Step 10  Go to Step 9 
9 Repair the open in the ignition feed circuit between the fuel injector and S114. Refer to Wiring Repairs in Wiring Systems.
Is the action complete?		 Go to Step 12  -
10
  1. Check for an open in the faulty fuel injector control circuit.
  2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.
  3. Repeat Step 5 through Step 10 until the injector test lamp flashes in all 4 fuel injector circuits.
Was a repair necessary?		 Go to Step 12  Go to Step 11 
11 Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement .
Is the action complete?		 Go to Step 12  -
12
  1. Use the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the conditions that caused the concern.
Does the fuel system now operate properly?		 Go to Step 13  Go to Diagnostic Aids
13 With a scan tool, observe the stored information, Capture Info.
Does the scan tool display any DTCs that you have not diagnosed?		 Go to Diagnostic Trouble Code (DTC) List System OK
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