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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2008 🢒 Captiva Sport 🢒 Diagnostic Navigation 🢒 Vehicle Diagnostic Information 🢒 Headlamps 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

Flash to Pass Switch Signal

4

4

4

--

Headlamp Switch High Beam Signal

4

4

4

--

Headlamp Switch Headlamps ON Signal

B257A 00

1

1

--

Headlamp Switch Headlamps OFF Signal

B257A 00

1

1

--

Headlamp High Beam Relay Control

3

3

B2580 00

--

Headlamp Low Beam Relay Control

2

2

B2575 00

--

LF High Beam Headlamp Control

3

3

3

--

LF Low Beam Headlamp Control

2

2

2

--

RF High Beam Headlamp Control

3

3

3

--

RF Low Beam Headlamp Control

2

2

2

--

LF Headlamp Ground

--

2

--

--

RF Headlamp Ground

--

2

--

--

Headlamp Switch Ground

--

2

--

--

Turn Signal/Multifunction Switch Ground

--

4

--

--

1. Headlamp Switch Malfunction

2. Headlamps Malfunction - Low Beam

3. Headlamps Malfunction - High Beam

4. Turn Signal/Multifunction Switch Malfunction

Circuit/System Description

When the headlamp switch is placed in the headlamp ON position, ground is applied to the body control module (BCM) through the headlamp ON signal circuit. The BCM then applies ground to the headlamp low beam relay control circuit which energizes the low beam relay. With the low beam relay energized, the switch contacts close allowing battery voltage to flow through the HDLP LO beam fuses to the low beam headlamps.

When the turn signal/multifunction switch is placed in the headlamps high or flash to pass (FTP) position, ground is applied to the body control module (BCM) through the headlamp high beam signal circuit or the flash to pass switch signal circuit. The BCM applies ground to the headlamp high beam relay control circuit which energizes the high beam relay. With the high beam relay energized, the switch contacts close allowing battery voltage to flow through the HDLP HI beam fuses to the high beam headlamps. With the headlamp dimmer switch in the high beam position the BCM sends a serial data message to the instrument panel cluster (IPC) requesting the IPC to illuminate the high beam indicator. Ground for the left headlamp is supplied at G101 and the right headlamp receives ground at G102.

Reference Information

Schematic Reference

Headlights/Daytime Running Lights (DRL) 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, observe the scan tool Headlamp Switch parameter while turning the headlamp switch ON and OFF. The parameter should change between Active and Inactive.
    2. ⇒If the parameter does not change between the commanded states, refer to Headlamp Switch Malfunction.
  2. Observe the scan tool Auto Hdlp. Disable Sw. parameter while applying and releasing the automatic lamp control disable switch. The parameter should change between Active and Inactive.
    3. ⇒If the parameter does not change between the commanded states, refer to Headlamp Switch Malfunction.
  3. Observe the scan tool Flash to Pass Switch parameter while applying and releasing the flash to pass switch. The parameter should change between Active and Inactive.
    4. ⇒If the parameter does not change between the commanded states, refer to Turn Signal/Multifunction Switch Malfunction.
  4. Observe the scan tool High Beam Select Switch parameter while applying and releasing the high beam select switch. The parameter should change between Active and Inactive.
    5. ⇒If the parameter does not change between the commanded states, refer to Turn Signal/Multifunction Switch Malfunction.
  5. Command the Low Beams ON and OFF with a scan tool. The low beam headlamps should turn ON and OFF when commanded.
    6. ⇒If the low beam headlamps do not turn ON and OFF when commanded, refer to Headlamps Malfunction - Low Beam.
  6. Command the High Beams ON and OFF with a scan tool. The low beam headlamps should turn ON and OFF when commanded.
    7. ⇒If the high beam headlamps do not turn ON and OFF when commanded, refer to Headlamps Malfunction - High Beam.

Circuit/System Testing

Headlamp Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the headlamp switch.
  2. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal 4.
    3. ⇒If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Headlamp Switch parameter is Inactive.
    4. ⇒If not the specified value, test the signal circuit terminal 6 for a short to ground. If the circuit tests normal, replace the BCM.
  4. Verify the scan tool Auto Hdlp. Disable Sw. parameter is Inactive.
    5. ⇒If not the specified value, test the signal circuit terminal 8 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 6 and ground. Verify the scan tool Headlamp 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. Install a 3A fused jumper wire between the signal circuit terminal 8 and ground. Verify the scan tool Auto Hdlp. Disable Sw. parameter is Active.
    7. ⇒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.
  7. If all circuits test normal, test or replace the headlamp switch.

Turn Signal/Multifunction Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the turn signal/multifunction switch.
  2. Ignition OFF, verify that a test lamp illuminates between B+ and the appropriate ground circuit terminal listed below.
    3. • Ground terminal A - with MH2
    • Ground terminal G - without MH2
    ⇒If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Flash to Pass Switch parameter is Inactive.
    4. ⇒If not the specified value, test the appropriate signal circuit terminal listed below for a short to ground. If the circuit tests normal, replace the BCM.
    • Signal terminal C - with LE5 and MH2
    • Signal terminal J - without LE5 and MH2
  4. Verify the scan tool High Beam Select Switch parameter is Inactive.
    5. ⇒If not the specified value, test the appropriate signal circuit terminal listed below for a short to ground. If the circuit tests normal, replace the BCM.
    • Signal terminal B - with LE5 and MH2
    • Signal terminal H - without LE5 and MH2
  5. Install a 3A fused jumper wire between the appropriate signal circuit terminal listed below and ground. Verify the scan tool Flash to Pass Switch parameter is Active.
    6. • Signal terminal C - with LE5 and MH2
    • Signal terminal J - without LE5 and MH2
    ⇒If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  6. Install a 3A fused jumper wire between the appropriate signal circuit terminal listed below and ground. Verify the scan tool High Beam Select Switch parameter is Active.
    7. • Signal terminal B - with LE5 and MH2
    • Signal terminal H - without LE5 and MH2
    ⇒If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  7. If all circuits test normal, test or replace the turn signal/multifunction switch.

Headlamps Malfunction - Low Beam

  1. Ignition OFF, remove the DRL fuse and disconnect the low beam relay.
  2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 87 and ground.
    3. ⇒If the test lamp illuminates, test the control circuit for a short to voltage.
  3. Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground.
    4. ⇒If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the control circuit terminal 87 for a short to ground. If the circuit tests normal, test or replace the low beam relay.
  4. Verify that a test lamp illuminates between the B+ circuit terminal 85 and ground.
    5. ⇒If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  5. Disconnect the harness connector at the inoperative low beam headlamp.
  6. Ignition OFF, scan tool OFF, exterior lamps OFF, test for less than 5 ohms between the ground circuit terminal B and ground.
    7. ⇒If greater than the specified range, test the ground circuit for an open/high resistance.
  7. Connect the harness connector at the inoperative low beam headlamp.
  8. Connect a 20A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the low beam headlamps illuminate.
    9. ⇒If the low beam headlamps do not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the inoperative low beam headlamp.
  9. Connect a test lamp between the B+ circuit terminal 85 and the control circuit terminal 86.
  10. Command the Low Beam headlamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    11. ⇒If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.
    ⇒If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
    ⇒If all circuits test normal, test or replace the low beam relay.

Headlamps Malfunction - High Beam

  1. Ignition OFF, remove the DRL fuse and disconnect the high beam relay.
  2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 87 and ground.
    3. ⇒If the test lamp illuminates, test the control circuit for a short to voltage.
  3. Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground.
    4. ⇒If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the control circuit terminal 87 for a short to ground. If the circuit tests normal, test or replace the high beam relay.
  4. Verify that a test lamp illuminates between the B+ circuit terminal 85 and ground.
    5. ⇒If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  5. Disconnect the harness connector at the inoperative high beam headlamp.
  6. Ignition OFF, scan tool OFF, exterior lamps OFF, test for less than 5 ohms between the ground circuit terminal B and ground.
    7. ⇒If greater than the specified range, test the ground circuit for an open/high resistance.
  7. Connect the harness connector at the inoperative high beam headlamp.
  8. Connect a 20A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the high beam headlamps illuminate.
    9. ⇒If the high beam headlamps do not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the inoperative high beam headlamp.
  9. Connect a test lamp between the B+ circuit terminal 85 and the control circuit terminal 86.
  10. Command the High Beam headlamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    11. ⇒If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.
    ⇒If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
    ⇒If all circuits test normal, test or replace the high beam relay.

High Beam Indicator Malfunction

Ignition ON, with a scan tool perform the Display Test for the instrument panel cluster (IPC) and observe the high beam indicator.

⇒If the high beam indicator illuminates during the test, replace the BCM.
⇒If the high beam indicator does not illuminate during the test or remains illuminated at all times, replace the IPC.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Headlamp Switch Replacement
    •  Headlamp Replacement
    •  Headlamp Bulb Replacement
    •  Relay Replacement
    •  Turn Signal Multifunction Switch Replacement
    •  Control Module References for BCM or IPC replacement, setup and programming