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HOMESERVICE MANUALSCHEVROLET2005OPTRA5 BASE, STANDARDREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMENGINE CONTROLS - 1.6L (L91) - DTC P1403 TO DTC P1661DTC P1611TEST DESCRIPTION
2005 Chevrolet Optra5 Base, Standard

Test Description

2005 Chevrolet Optra5 Base, StandardSECTION Test Description

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

  1. 5:  This step tests the control circuit for a shorted to voltage.
  2. 6:  This step tests the control circuit for an open.
  3. 8:  This step tests the control circuit for high resistance.
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
  1. Turn ON the ignition, with the engine OFF.
  2. Command the engine controls ignition relay ON with a scan tool.
Do you hear an audible click from the relay?		 - Go to Step 3  Go to Step 4 
3
  1. Observe the Freeze Frame/Failure Records data for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Operate the vehicle within the Conditions for Running the DTC.
Did the DTC fail this ignition?		 - Go to Step 4  Go to Diagnostic Aids
4
  1. Turn OFF the ignition.
  2. Disconnect the ENGINE relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the battery positive voltage circuit of the ENGINE relay coil with a test lamp connected to a good ground.
Does the test lamp illuminate?		 - Go to Step 5  Go to Step 12 
5 
  1. Turn OFF the ignition.
  2. Probe the control circuit of the ENGINE relay with a test lamp connected to battery positive voltage.
Does the test lamp illuminate?		 - Go to Step 9  Go to Step 6 
6 
  1. Turn ON the ignition, with the engine OFF.
  2. Probe the control circuit of the ENGINE relay with a test lamp connected to battery positive voltage.
Does the test lamp illuminate?		 - Go to Step 7  Go to Step 9 
7
  1. Turn OFF the ignition.
  2. Disconnect the ECM 1 fuse in the underhood fuse block.
  3. Measure the resistance of the battery positive circuit of the ENGINE relay coil from the ENGINE MAIN fuse terminal to the relay terminal.
Is the resistance less than the specified value?		 3 Ω Go to Step 8  Go to Step 12 
8 
  1. Turn ON the ignition, with the engine OFF.
    2. IMPORTANT: Use a test lamp that measures between 25-30 ohms.
  2. Probe the control circuit of the ENGINE relay with a test lamp connected to battery positive voltage.
  3. Measure the voltage from the probe of the test lamp to a good ground with a DMM.
Is the voltage less than the specified value?		 2.5 V Go to Step 10  Go to Step 9 
9 Test the control circuit of the ENGINE relay for one of the following conditions:
  • A short to ground
  • An open
  • High resistance

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 15  Go to Step 11 
10 Test for shorted terminals and poor connections at the ENGINE relay. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 15  Go to Step 13 
11 Test for shorted terminals and poor connections at the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 15  Go to Step 14 
12 Repair an open or high resistance in the battery positive voltage circuit of the ENGINE relay coil. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 15  -
13 Replace the ENGINE relay.
Did you complete the replacement?		 - Go to Step 15  -
14 Replace the ECM. Refer to Engine Control Module (ECM) Replacement .
Did you complete the replacement?		 - Go to Step 15  -
15
  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.
Did the DTC fail this ignition?		 - Go to Step 2  Go to Step 16 
16 Are there any DTCs that have not been diagnosed? - Go to Diagnostic Trouble Code (DTC) List System OK
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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.