Park, License, and/or Tail Lamps Malfunction
Park, License, and/or Tail Lamps Malfunction
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.
Diagnostic Fault Information
Circuit/System Description
Battery voltage is applied at all times to both the coil and switch sides of the PRK LAMP relay located in the underhood fuse block. The turn signal/multifunction switch is suppled with ground at all times. When the headlamp switch is placed in either the HEAD or PARK position, ground is applied to the park lamp signal circuit to the body control module (BCM). The BCM responds by applying ground to the park lamp relay control circuit. This energizes the park lamp relay coil causing the relay switch contacts to close allowing battery voltage to flow to all of the park, tail, license, and marker lamps.
Reference Information
Schematic Reference
Exterior Lights Schematics (Exterior Lights Schematics)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Exterior Lighting Systems Description and Operation (Exterior Lighting Systems Description and Operation)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
1. Ignition ON, observe the scan tool Park Lamp Switch parameter while cycling the park lamp switch ON and OFF. The reading should toggle between Active and Inactive.
• If the readings do not change between the commanded states, refer to Park Lamp Switch Malfunction.
2. Command the Parking Lamps ON and OFF with a scan tool. The park lamps should turn ON and OFF when changing between the commanded states.
• If the park lamps do not turn ON and OFF when commanded, refer to Park, License, and/or Tail Lamps Malfunction.
Circuit/System Testing
Park Lamp Switch Malfunction
1. Ignition OFF, disconnect the X1 harness connector at the turn signal/multifunction switch.
2. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal 1.
• If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Park Lamp Switch parameter is Inactive.
• If not the specified value, test the signal circuit terminal 3 for a short to ground. If the circuit tests normal, replace the BCM.
4. Install a 3 A fused jumper wire between the signal circuit terminal 3 and ground. Verify the scan tool Park Lamp Switch parameter is Active.
• 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.
5. If all circuits test normal, test or replace the turn signal/multifunction switch.
Park, License, and/or Tail Lamps Malfunction
1. Ignition OFF, disconnect the X2 harness connector at the underhood fuse block.
2. Connect a test lamp between the control circuit terminal B7 and B+.
3. Command the Parking Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
• 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.
4. Ignition OFF, connect the X2 harness connector at the underhood fuse block.
5. Disconnect the harness connector at the appropriate park/license/marker lamp.
6. Ignition OFF, exterior lamps OFF, test for less than 5 ohm between the ground circuit terminal listed below and ground.
* License lamp - terminal B
* Tail/stop and turn signal lamp - terminal C
* Marker lamp - terminal B
* Park/turn signal lamp - terminal G
• If greater than the specified range, test the ground circuit for an open/high resistance.
7. Connect a test lamp between the control circuit terminal listed below and ground.
* License lamp - terminal A
* Tail/stop and turn signal lamp - terminal B
* Marker lamp - terminal A
* Park/turn signal lamp - terminal B
8. Command the Parking Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the underhood fuse block.
• If the test lamp is always OFF and the circuit fuse is good, test the control circuit for an open/high resistance. If the circuit tests normal, replace the underhood fuse block.
• If the test lamp is always OFF and the circuit fuse is open, test the control circuit for a short to ground. If the circuit tests normal, replace the underhood fuse block.
9. If all circuits test normal, replace the park/license/marker lamp.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Front Side Marker Lamp Bulb Replacement (Front Side Marker Lamp Bulb Replacement)
* Rear License Plate Lamp Bulb Replacement (Chevrolet) (Service and Repair)
* Rear License Plate Lamp Replacement (Chevrolet) (Service and Repair)
* Rear Side Marker Lamp Bulb Replacement (Chevrolet Sedan) (Rear Side Marker Lamp Bulb Replacement (Sedan))
* Tail Lamp Replacement (Chevrolet Coupe) (Tail Lamp Replacement (Coupe))Tail Lamp Replacement (Chevrolet, Pontiac Sedan) (Tail Lamp Replacement (Sedan))Tail Lamp Replacement (Chevrolet European) (Tail Lamp Replacement (European))
* Turn Signal Multifunction Switch Replacement (Turn Signal Multifunction Switch Replacement)
* Underhood Electrical Center or Junction Block Bracket Replacement (Removal and Replacement)
* Control Module References (Programming and Relearning) for BCM replacement, setup, and programming