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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2009 🢒 Express 🢒 Diagnostic Navigation 🢒 Vehicle Diagnostic Information 🢒 Hazard Lamps Malfunction

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Hazard Switch Signal

2

2

2

--

Turn Signal Control

1

1

1

--

Turn Signal/Multifunction Switch Ground

--

2

--

--

Turn Signal Lamp Ground

--

1

--

--

1. Hazard Lamps Malfunction

2. Turn Signal/Multifunction Switch Malfunction

Circuit/System Description

The body control module (BCM) controls the hazard lamps based on inputs from the hazard switch. With the hazard switch closed, a ground path is provided on the hazards switch signal circuit, indicating a hazard lamp request. When this request is seen, the BCM will pulse the turn signal lamp supply voltage circuits, illuminating the turn signal lamps.

Reference Information

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification
  1. Ignition ON, command the listed turn signal lamps ON and OFF with a scan tool. The lamps should turn ON and OFF between the commanded states.
    2. • LF Turn Signal
    • RF Turn Signal
    • LR Turn Signal
    • RR Turn Signal
    ⇒If the lamps do not turn ON and OFF, refer to Turn Signal Lamps and/or Indicators Malfunction.
  2. Observe the scan tool Hazard Lamp Switch parameter while cycling the hazard switch ON and OFF. The parameter should change between Active and Inactive.
    3. ⇒If the parameter does not cycle between the specified values, refer to Hazard Switch Malfunction.
  3. Press and release the hazard switch. All applicable lamps should flash ON and OFF.
    4. ⇒If one or more of the lamps flash ON and OFF, refer to Turn Signal Lamps and/or Indicators Malfunction
    ⇒If none of the lamps flash ON and OFF, refer to Hazard Switch Malfunction.

Circuit/System Testing

Hazard Switch Malfunction

  1. Ignition OFF, disconnect the X1 harness connector at the turn signal/multifunction switch.
  2. Test for less than 5 ohms between the ground circuit terminal C and ground.
    3. ⇒If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Test for less than 5 ohms between the ground circuit terminal F and ground.
    4. ⇒If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Ignition ON, verify the scan tool Hazard Lamp Switch parameter is Inactive.
    5. ⇒If not the specified value, test the signal circuit terminal G for a short to ground. If the circuit tests normal, replace the BCM.
  5. Install a 3A fused jumper wire between the signal circuit terminal G and ground. Verify the scan tool Hazard Lamp Switch parameter is Active.
    6. ⇒If not the specified value, test the signal circuit for a short to voltage or and open/high resistance. If the circuit tests normal, replace the BCM.
  6. If all circuits test normal, replace the turn signal/multifunction switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Turn Signal Multifunction Switch Replacement
    •  Control Module References for BCM replacement, setup, and programming