Buick Regal: Head-Up Display 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

1. Head-Up Display Malfunction

Circuit/System Description

The head-up display projects a full color image onto the windshield and is only viewable from the driver seat. The image location and brightness is adjustable using the head-up display switch. The image information is received from the instrument cluster through a video cable.

The head-up display is a slave device to the instrument cluster. The head-up display is powered through ignition voltage and ground. It communicates directly with instrument cluster via serial data and only has limited self-diagnosis capacity. Head-up display DTCs are reported through the Instrument Cluster.

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.

Reference Information

Schematic Reference

Head-Up Display Wiring Schematics

Steering Wheel Secondary/Configurable Control 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 Head-Up Display Switch 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 Inoperative Head-Up Display Switch Circuit/System Testing.

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

3. Verify the P29 Head-Up Display performs the following function with the switch in the appropriate state:

• DIM + Switch - Head-up display brightness increases
• DIM - Switch - Head-up display brightness decreases
• UP Switch - Head-up display image moves up
• DOWN Switch - Head-up display image moves down
• PAGE Switch - Head-up display image changes pages
• If the P29 Head-Up Display does not perform the expected function with the switch in the appropriate state

Refer to Inoperative Head-Up display Circuit/System Testing.

• Go to next step: If the P29 Head-Up Display performs the expected function with the switch in the appropriate state

4. All OK.

Circuit/System Testing

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

Inoperative Head-Up Display

1. Ignition OFF, disconnect the harness connector at the P29 Head-Up Display, ignition ON.

2. Test for 2 - 10 V between the S70R Steering Wheel Controls Switch - Right serial data circuit terminal 7 and ground.

• If less than 2 V

1. Ignition OFF, disconnect the harness connector at the P16 Instrument Cluster.
2. Test for infinite resistance between the S70R Steering Wheel Controls Switch - Right serial data circuit terminal 7 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 infinite resistance between the P29 Head-Up Display serial data circuit terminal 1 and ground.
   • If less than infinite resistance, repair the short to ground on the circuit.
   • Go to next step: If infinite resistance
4. Test for less than 2 Ω in the S70R Steering Wheel Controls Switch - Right serial data circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, replace the P16 Instrument Cluster.

• If greater than 10 V

1. Ignition OFF, disconnect the harness connector at the P16 Instrument Cluster, ignition ON.
2. Test for less than 1 V between the S70R Steering Wheel Controls Switch - Right serial data circuit terminal 7 and ground.
   • If 1 V or greater, repair the short to voltage on the circuit.
   • Go to next step: If less than 1 V.
3. Test for less than 1 V between the P29 Head-Up Display serial data circuit terminal 1 and ground.
   • If 1 V or greater, repair the short to voltage on the circuit.
   • If less than 1 V, replace the P16 Instrument Cluster.

• Go to next step: If between 2 - 10 V

3. Connect the harness connector at the S70R Steering Wheel Controls Switch - Right. Ignition ON.

4. Verify steering wheel controls function properly.

• If steering wheel controls function properly

Replace P29 Head-Up Display.

• Go to next step: If steering wheel controls do not function properly

5. Ignition OFF. Disconnect harness connector at the S70R Steering Wheel Controls Switch - Right.

Connect the harness connector at the and P29 Head-Up Display. Ignition ON.

6. Verify head-up display functions properly.

• If head-up display functions properly

Replace S70R Steering Wheel Controls Switch - Right.

• Go to next step: If head-up display does not function properly

7. Replace the video cable between the P29 Head-Up Display and the P16 Instrument Cluster.

Ignition ON.

8. Verify head-up display functions properly.

• If head-up display functions properly

All OK.

• Go to next step: If head-up display does not function properly

9. Replace P16 Instrument Cluster.

Inoperative Head-Up Display Switch

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. Ignition ON.

4. Test for 4.8 - 5.2 V between the signal circuit terminal 4 and ground.

• If less than 4.8 V

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.

• If greater than 5.2 V

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

• Go to next step: If between 4.8 - 5.2 V

5. 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
• Control Module References for control module replacement, programming, and setup

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