Buick Regal: Headlamp Leveling Malfunction (Manual)
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
1. Headlamp Leveling Malfunction
Circuit/System Description
Each headlamp assembly contains a headlamp leveling actuator that is
controlled by the headlamp
leveling switch. The headlamp leveling switch is supplied with ignition voltage
and ground and contains
a resistor ladder with 4 positions for adjusting the headlamps up or down. When
the headlamp leveling
switch is activated to the desired position, voltage from the B+ ignition
circuit is pulled down through
the resistor ladder and the voltage is applied to the left and right headlamp
leveling actuators via the
headlamp leveling control circuits. The headlamp leveling actuators are supplied
with B+ and ground.
When the headlamp leveling switch is activated, the left and right headlamp
leveling actuators respond
by moving the headlamps to the desired position.
Diagnostic Aids
For testing purposes, the vehicle battery must be fully charged.
Reference Information
Schematic Reference
Headlights/Daytime Running Lights (DRL) Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEWS - INDEX
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 Testing
1. Ignition OFF, exterior lamps OFF, disconnect the harness connector at the
appropriate E13
Headlamp Assembly. It may take up to 2 min for all vehicle systems to power
down.
2. Test for less than 10 Ω between the ground circuit terminal 7 and ground.
- Ignition OFF.
- Test for less than 2 Ω in the ground circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, repair the open/high resistance in the ground
connection.
- Go to next step: If less than 10 Ω
3. Ignition ON.
4. Verify a test lamp illuminates between the B+ ignition circuit terminal 6
and ground.
- If the test lamp does not illuminate
- Ignition OFF, remove the F44UA fuse at the X50A Fuse Block - Underhood.
- Test for infinite resistance between the B+ ignition circuit and ground.
- If less than infinite resistance, repair the short to ground on the
circuit.
- Go to next step: If infinite resistance
- Test for less than 2 Ω in the B+ circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the X50A Fuse Block - Underhood.
- Go to next step: If the test lamp illuminates
5. Ignition OFF, scan tool disconnected, all doors closed, all accessories
OFF, disconnect the harness
connector at the S30 Headlamp Switch. It may take up to 2 min for all vehicle
systems to power
down.
6. Test for less than 15 Ω between the ground circuit terminal 8 and ground.
- Ignition OFF.
- Test for less than 2 Ω in the ground circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, repair the open/high resistance in the ground
connection.
- Go to next step: If less than 15 Ω
7. Ignition ON.
8. Verify a test lamp illuminates between the B+ ignition circuit terminal 4
and ground.
- If the test lamp does not illuminate
- Ignition OFF, remove the F27UA fuse at the X50A Fuse Block - Underhood.
- Test for infinite resistance between the B+ circuit and ground.
- If less than infinite resistance, repair the short to ground on the
circuit.
- Go to next step: If infinite resistance
- Test for less than 2 Ω in the B+ circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the X50A Fuse Block - Underhood.
- Go to next step: If the test lamp illuminates
9. Ignition OFF, connect the harness connector at the S30 Headlamp Switch.
10. Ignition ON, exterior lights OFF.
11. Test the voltage between the control circuit terminal 8 at the E13 Headlamp
Assembly harness
connector and ground for each headlamp leveling switch position listed below.
- Headlamp leveling switch position 0 - 10 V - 11 V
- Headlamp leveling switch position 1 - 8.5 V - 9.9 V
- Headlamp leveling switch position 2 - 8 V - 9 V
- Headlamp leveling switch position 3 - 6 V - 7 V
- If less than the specified voltage range for each headlamp leveling
switch position
- Ignition OFF, disconnect the harness connector at the S30 Headlamp
Switch.
- Test for infinite resistance between the control circuit terminal 9 and
ground.
- If less than infinite resistance, repair the short to ground on the
circuit.
- Go to next step: If infinite resistance
- Test for less than 2 Ω in the control circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the S30 Headlamp Switch.
- If greater than the specified voltage range for each headlamp
leveling switch position
- Ignition OFF, disconnect the harness connector at the S30 Headlamp
Switch, ignition ON.
- Test for less than 1 V between the control circuit terminal 9 and
ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V, replace the S30 Headlamp Switch.
- Go to next step: If within the specified voltage range for each
headlamp leveling switch
position
12. Test or replace the E13 Headlamp Assembly.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
- Headlamp Switch Replacement
- Headlamp Replacement
READ NEXT:
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.
Diag
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.
Diag
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.
Diag
SEE MORE:
If equipped with base seats, the
vehicle's front seats have adjustable
head restraints in the outboard
seating positions.
If equipped with GS Model seats,
the vehicle's front seats have head
restraints in the outboard seating
positions that cannot be adjusted.
Warning:
With head restraints that are
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