Park Lamps Malfunction
Park Lamps MalfunctionDiagnostic Instructions
^ Perform the [Diagnostic System Check - Vehicle Diagnostic Information] prior to using this diagnostic procedure. Diagnostic System Check - Vehicle Diagnostic Information
^ Review [Strategy Based Diagnosis] for an overview of the diagnostic approach. Strategy Based Diagnosis
^ [Diagnostic Procedure Instructions - Vehicle Diagnostic Information] provides an overview of each diagnostic category. Diagnostic Procedure Instructions - Vehicle Diagnostic Information
Diagnostic Fault Information
Circuit/System Description
The vehicle park, license, and tail lamps are controlled by the body control module (BCM) based on an input from the headlamp switch. The headlamp switch has four positions: Off, Auto, Park, and Headlamps. The default headlamp switch position is Auto, in which the BCM uses the ambient light sensor to determine when exterior lamps are needed. The Off portion of the headlamp switch is a momentary switch which overrides the automatic lamps and will turn off the vehicle lamps. The Park position of the headlamp switch will only illuminate the vehicle parking lamps. The Headlamp position of the headlamp switch will illuminate both the parking lamps, as well has the headlamps. With the headlamp switch in the Park position, the park lamp switch on signal circuit is grounded, prompting the BCM to turn on the exterior lamps, regardless of other factors such as ambient light.
When a park lamp request is received, the BCM grounds the park lamp relay control circuit. This energizes the coil in the PARK LP PCB relay, causing the relay switch to close. Battery voltage is then applied through the LT PARK and RT PARK LAMP fuses and the park lamp supply voltage circuits illuminating the exterior lamps.
Circuit/System Verification
1. Ignition ON, observe the scan tool BCM Parklamp Switch parameter while cycling the headlamp switch between the Park and Off positions. The parameter should cycle between Active and Inactive.
^ If the parameter does not cycle between the specified values, refer to Headlamp Switch Circuit Test.
2. Command the Parking Lamps ON and OFF with a scan tool. Verify the park, license, and tail lamps turn ON and OFF between commanded states.
^ If any of the lamps are always OFF or remain always ON, refer to Park, License, and/or Tail Lamps Circuit Test.
Circuit/System Testing
Headlamp Switch Circuit Test
1. Ignition OFF, disconnect the X1 harness connector at the turn signal/multifunction switch.
2. Ignition OFF, verify that a test lamp illuminates between the ground circuit terminal 1 and B+.
^ If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool BCM Parklamp 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 3A fused jumper wire between the signal circuit terminal 3 and ground. Verify the scan tool Parklamp Switch parameter is Active.
^ 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.
5. If all circuits test normal, test or replace the turn signal/multifunction switch.
Park, License, and/or Tail Lamps Circuit Test
1. Ignition OFF, disconnect the X2 harness connector at the underhood fuse block.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 6 and ground.
^ If the test lamp illuminates, test the control circuit for a short to voltage.
3. Connect a test lamp between the control circuit terminal 6 and B+.
4. 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.
5. Ignition OFF, reconnect the X2 harness connector.
6. Disconnect the harness connector at the inoperative lamp.
7. Test for less than 5.0 ohms of resistance between the appropriate ground circuit listed below and ground.
^ Chevrolet front park/turn signal lamp - terminal 2
^ Pontiac front park/turn signal lamp - terminal 3
^ Suzuki front park/turn signal lamp - terminal G
^ Suzuki front park or maker lamp - terminal 2
^ Chevrolet and Pontiac rear park lamps - terminal GRND
^ Suzuki rear park lamps except for right rear park/turn signal lamp - terminal 3
^ Suzuki right rear park/turn signal lamp - terminal G
^ All other marker lamps - terminal 2
^ License lamps - terminal B
^ If greater than the specified range, test the ground circuit for an open/high resistance.
8. Connect a test lamp between the inoperative lamp supply voltage circuit listed below and ground.
^ Chevrolet front park/turn signal lamp - terminal 1
^ Pontiac front park/turn signal lamp - terminal 2
^ Suzuki front park/turn signal lamp - terminal MAJ
^ Suzuki front park or maker lamp - terminal 1
^ Chevrolet and Pontiac rear park lamps - terminal Major
^ Suzuki rear park lamps - terminal MAJ
^ All other marker lamps - terminal 1
^ License lamps - terminal A
9. 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 does not illuminate, test the supply voltage circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the underhood fuse block.
10. If all circuits test normal, test or replace the bulb or lamp assembly.
Repair Instructions
Perform the [Diagnostic Repair Verification - Vehicle Diagnostic Information] after completing the diagnostic procedure. Diagnostic Repair Verification - Vehicle Diagnostic Information
^ [Control Module References] for BCM replacement, setup and programming Programming and Relearning
^ [Front Side Marker Lamp Bulb Replacement]
^ [Park/Turn Signal Lamp Bulb Replacement]
^ [License Lamp Bulb Replacement]
^ [Tail Lamp Replacement]
^ [Turn Signal Multifunction Switch Replacement]
^ [Underhood Electrical Center or Junction Block Replacement]