B3634

DTC B3634

DTC Descriptors

DTC B3634
- Head-Up Display (HUD) Dimming Up Switch Short to Ground.

Diagnostic Fault Information

Important: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview






Circuit/System Description

The head-up display (HUD) dimming switch is a momentary press switch that adjusts the HUD display brightness. The HUD dimmer switch controls the intensity of the brightness. The HUD senses when the dimming switch is active and adjusts the display brightness until the desired intensity is attained. When the HUD dimming switch is pressed and the ignition is in the RUN position, the dimming switch signal to the HUD is low.

Conditions for Running the DTC

The ignition is in RUN.

Conditions for Setting the DTC

The HUD detects that the HUD dimming up switch signal circuit is low for greater than 60 seconds.

Action Taken When the DTC Sets

The HUD ignores the malfunctioning switch circuit.

Conditions for Clearing the DTC

* The DTC becomes history when the conditions for setting the DTC are no longer present.
* The HUD receives a clear code command from the scan tool.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the head-up display (HUD) switch.
2. Test for less than 1.0 ohm of resistance between the HUD switch ground circuit and low reference.

• If greater than 1.0 ohm, test the HUD switch ground circuit for an open/high resistance.

3. Ignition ON, verify that a test lamp does not illuminate when connected between the HUD dimming switch signal circuit and B+.

• If the test lamp illuminates, test the HUD dimming switch signal circuit for a short to ground. If the circuit tests normal replace the HUD.

4. Install a 3-A fused jumper wire between the HUD dimming switch signal circuit and ground. Verify the scan tool Adjust Display Down Switch parameter is Active.

• If not Active, test the HUD dimming switch signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the HUD.

5. If all circuits test normal, test or replace the HUD switch.

Repair Instructions

Important: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Programming and RelearningProgramming and Relearning
* Head Up Display Switch Replacement