Buick Regal: DTC B361B

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.

DTC Descriptor

DTC B361B 02

Head-Up Display Switch Short to Ground

DTC B361B 05

Head-Up Display Switch High Voltage/Open

DTC B361B 59

Head-Up Display Switch Protection Time-Out

Diagnostic Fault Information

Circuit/System Description

The head-up display switch is a multiplexed switch that controls the head-up display based on driver inputs. The head-up display provides the switch with a low reference and monitors a signal circuit. The head-up display switch is made up of a resistor ladder and three switches: Dim +/-, Up/Down, and Page.

When a switch is pressed, the signal voltage is pulled low through the resistor ladder. When pressed, each of the switches will result in a different signal voltage seen by the head-up display, depending on the switch's location on the resistor ladder.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

B361B 02

The head-up display switch signal voltage is less than 1 V

B361B 05

The head-up display switch signal voltage is greater than 11.5 V

B361B 59

The head-up display switch is stuck

Action Taken When the DTC Sets

The head-up display ignores the head-up display switch inputs

Conditions for Clearing the DTC

The DTC will become history if the head-up display no longer detects a malfunction

Reference Information

Schematic Reference

Head-Up Display Wiring Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEW INDEX

Description and Operation

Instrument Cluster 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.

2. While holding each switch listed below, verify the scan tool Heads Up Display Switch State parameter is as follows:

• DIM + Switch - HUD Dimming Up/Down Pressed
• DIM - Switch - HUD Dimming Up/Down Pressed
• UP Switch - HUD Movement
• DOWN Switch - HUD Movement
• PAGE Switch - HUD Page Switch
• If the scan tool parameter does not equal the expected result with the switch in the appropriate state

Refer to Circuit/System Testing.

• Go to next step: If the scan tool parameter equals the expected result with the switch in the appropriate state

3. All OK.

Circuit/System Testing

NOTE: Circuit/System Verification must be performed before proceeding with Circuit/System Testing.

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the S27 Head-Up Display Switch. It may take up to 2 min for all vehicle systems to power down.

2. Test for less than 10 Ω between the low reference circuit terminal 3 and ground.

• If 10 Ω or greater

1. Ignition OFF, disconnect the harness connector at the P29 Head-Up Display.
2. Test for less than 2 Ω in the low reference circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, replace the P29 Head-Up Display.

• Go to next step: If less than 10 Ω

3. Test for less than 1 V between the signal circuit terminal 4 and ground.

• If 1 V or greater

1. Ignition OFF, disconnect the harness connector at the P29 Head-Up Display.
2. Test for less than 1 V between the signal circuit and ground.
   • If 1 V or greater, repair the short to voltage in the circuit.
   • If less than 1 V, replace the P29 Head-Up Display.

• Go to next step: If less than 1 V

4. Ignition ON.

5. Test for B+ between the signal circuit terminal 4 and ground.

• If less than B+

1. Ignition OFF, disconnect the harness connector at the P29 Head-Up Display.
2. Test for infinite resistance between the signal circuit and ground.
   • If less than infinite resistance, repair the short to ground on the circuit.
   • Go to next step: If infinite resistance
3. Test for less than 2 Ω in the signal circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, replace the P29 Head-Up Display.

• Go to next step: If B+

6. Test or replace the S27 Head-Up Display switch.

Component Testing

1. Ignition OFF, disconnect the harness connector at the S27 Head-Up Display Switch.

2. Test for 3.4K - 4.2K Ω between the signal terminal 4 and the low reference terminal 3.

• If not between 3.4K - 4.2K Ω

Replace the S27 Head-Up Display Switch.

• Go to next step: If between 3.4K - 4.2K Ω

3. Test for 87 - 107 Ω between the signal terminal 4 and the low reference terminal 3 with the Dim + switch pressed.

• If not between 87 - 107 Ω

Replace the S27 Head-Up Display Switch.

• Go to next step: If between 87 - 107 Ω

4. Test for 291 - 356 Ω between the signal terminal 4 and the low reference terminal 3 with the Dim - switch pressed.

• If not between 291 - 356 Ω

Replace the S27 Head-Up Display Switch.

• Go to next step: If between 291 - 356 Ω

5. Test for 575 - 704 Ω between the signal terminal 4 and the low reference terminal 3 with the Up switch pressed.

• If not between 575 - 704 Ω

Replace the S27 Head-Up Display Switch.

• Go to next step: If between 575 - 704 Ω

6. Test for 1K - 1.2K Ω between the signal terminal 4 and the low reference terminal 3 with the Down switch pressed.

• If not between 1K - 1.2K Ω

Replace the S27 Head-Up Display Switch.

• Go to next step: If between 1K - 1.2K Ω

7. Test for 1.7K - 2.1K Ω between the signal terminal 4 and the low reference terminal 3 with the Page switch pressed.

• If not between 1.7K - 2.1K Ω

Replace the S27 Head-Up Display Switch.

• Go to next step: If between 1.7K - 2.1K Ω

8. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Displays and Gauges Component Replacement Reference.

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