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Tahoe / Yukon Service Manual

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

Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performanc
B+ U1518 00 U1518 00 — —
Serial Data 1, U1518 00 U1518 00 1, U1518 00 —
Video Signal 1 1 1 1
Switch Signal B110A 11 B110A 15 B110A 15 B110A 63
Switch Low Reference — B110A 15 — —
Ground — U1518 00 — —
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 Panel Cluster Control Module through a video cable. The head-up display is a slave device to the Instrument Panel Cluster Control Module. The head- up display is powered through ignition voltage and ground. It communicates directly with Instrument Panel Cluster Control Module via serial data and only has limited self-diagnosis capacity. Head-up display DTCs are reported through the Instrument Panel Cluster Control Module. 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 Schematics Steering Wheel Secondary/Configurable Control Schematics Connector End View Reference Master Electrical Component List 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/Vehicle in Service Mode.
  2. Verify a test pattern is displayed is displayed on the P29 Head-Up Display when performing the Head-Up Display Pattern Check on the scan tool. ⇒ If the test pattern is not displayed Refer to Inoperative Head-Up display Circuit/System Testing. ⇓ If the test pattern is displayed
  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 INFO Switch – Head-up display image changes pages POWER Switch – Head-up display image turns off ⇒ 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 Switch Circuit/System Testing. ⇓ If the P29 Head-Up Display performs the expected function with the switch in the appropriate state
  4. All OK. Circuit/System Testing
  1. Ignition/Vehicle & All vehicle systems » Off
  2. Disconnect the electrical connector: X4 @ P16 Instrument Cluster
  3. Disconnect the electrical connector: X1 @ P29 Head-Up Display
  4. Disconnect the electrical connector: S70R Steering Wheel Controls Switch - Right
  5. Ignition » On / Vehicle » In Service Mode
  6. Test for less than 1 V between the test points: Serial Data circuit terminal 20 @ P16 Instrument Cluster Component harness & Ground ⇒ If 1 V or greater Repair the short to voltage on the circuit. ⇓ If less than 1 V
  7. Ignition/Vehicle & All vehicle systems » Off
  8. Test for infinite resistance between the test points: Serial Data circuit terminal 20 @ P16 Instrument Cluster Component harness & Ground ⇒ If less than infinite resistance » Repair the short to ground on the circuit. ⇓ If infinite resistance
  9. Replace the component: Low-Voltage Differential Signaling Cable @ P29 Head-Up Display & P16 Instrument Cluster
  10. Connect the component: P16 Instrument Cluster & P29 Head-Up Display & S70R Steering Wheel Controls Switch - Right
  11. Ignition » On / Vehicle » In Service Mode
  12. Perform the scan tool function: Head-Up Display Pattern Check
  13. Verify the component activates: P29 Head-Up Display ⇒ If the specified state All OK. ⇓ If not the specified state
  14. Disconnect the electrical connector: S70R Steering Wheel Controls Switch - Right
  15. Ignition » On / Vehicle » In Service Mode
  16. Perform the scan tool function: Head-Up Display Pattern Check
  17. Verify the component activates: P29 Head-Up Display ⇒ If the specified state Replace the component: S70R Steering Wheel Controls Switch - Right ⇓ If not the specified state
  18. Disconnect the electrical connector: P29 Head-Up Display
  19. Connect the component: S70R Steering Wheel Controls Switch - Right
  20. Ignition » On / Vehicle » In Service Mode
  21. Verify the function: Steering Wheel Controls ⇒ If the specified state Replace the component: P29 Head-Up Display ⇓ If not the specified state
  22. Replace the component: P16 Instrument Cluster Inoperative Head-Up Display Switch
  23. Ignition OFF/Vehicle 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.
  24. Test for less than 10 Ω between the low reference circuit terminal 3 and ground. ⇒ If 10 Ω or greater 2.1. Ignition OFF/Vehicle OFF, disconnect the harness connector at the P29 Head-Up Display . 2.2. 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 . ⇓ If less than 10 Ω
  25. Test for 4.8–5.2 V between the signal circuit terminal 4 and ground. ⇒ If less than 4.8 V 3.1. Ignition OFF/Vehicle OFF, disconnect the harness connector at the P29 Head-Up Display . 3.2. Test for infinite resistance between the signal circuit and ground. ⇒ If less than infinite resistance, repair the short to ground on the circuit. ⇓ If infinite resistance 3.3. 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 3.1. Ignition OFF/Vehicle OFF, disconnect the harness connector at the P29 Head-Up Display , ignition ON. 3.2. 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 . ⇓ If between 4.8–5.2 V
  26. Test or replace the S27 Head-Up Display Switch h. Component Testing S27 Head-Up Display Switch
  27. Ignition OFF/Vehicle OFF, disconnect the harness connector at the S27 Head-Up Display Switch .
  28. Test for 14K – 16K Ω between the signal terminal 4 and the low reference terminal 3. ⇒ If not between 14K – 16K Ω Replace the S27 Head-Up Display Switch . ⇓ If between 14K – 16K Ω
  29. Test for 6K – 8K Ω between the signal terminal 4 and the low reference terminal 3 with the DIM - Switch pressed. ⇒ If not between 6K – 8K Ω Replace the S27 Head-Up Display Switch . ⇓ If between 6K – 8K Ω
  30. Test for 3.5K – 4.3K Ω between the signal terminal 4 and the low reference terminal 3 with the DIM + Switch pressed. ⇒ If not between 3.5K – 4.3K Ω Replace the S27 Head-Up Display Switch . ⇓ If between 3.5K – 4.3K Ω
  31. Test for 2.2K – 2.6K Ω between the signal terminal 4 and the low reference terminal 3 with the INFO Switch pressed. ⇒ If not between 2.2K – 2.6K Ω Replace the S27 Head-Up Display Switch h. ⇓ If between 2.2K – 2.6K Ω
  32. Test for 1.3K – 1.6K Ω between the signal terminal 4 and the low reference terminal 3 with the POWER Switch pressed. ⇒ If not between 1.3K – 1.6K Ω Replace the S27 Head-Up Display Switch . ⇓ If between 1.3K – 1.6K Ω
  33. Test for 750 – 910 Ω between the signal terminal 4 and the low reference terminal 3 with the DOWN Switch pressed. ⇒ If not between 750 – 910 Ω Replace the S27 Head-Up Display Switch . ⇓ If between 750 – 910 Ω
  34. Test for 360 – 440 Ω between the signal terminal 4 and the low reference terminal 3 with the UP Switch pressed. ⇒ If not between 360 – 440 Ω Replace the S27 Head-Up Display Switch . ⇓ If between 360 – 440 Ω
  35. 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