B3621

DTC B3621

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview)provides an overview of each diagnostic category.



DTC Descriptor
DTC B3621
- Head-Up Display (HUD) Information Down Switch




Diagnostic Fault Information






Circuit/System Description

The head-up display (HUD) image down switch is used to vertically adjust the HUD image on the windshield to accommodate various vehicle operator heights. The HUD monitors the image down switch signal circuit in order to adjust image positions. When the HUD image down switch is depressed and the ignition is in the RUN position, the 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 image down 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 history DTC clears after 40 malfunction-free warm-up cycles.



Reference Information
Schematic Reference

Head Up Display Schematics (Head Up Display Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Head Up Display (HUD) Description and Operation (Head Up Display (HUD) Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning)for Scan Tool Information


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 low reference circuit terminal 3 and ground.

• If greater than the specified value, test the low reference circuit for an open/high resistance.

3. Ignition ON, test for 4.8-5.2 volts between the HUD image down control circuit terminal 4 and ground.

• If less than the specified range, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the HUD.

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



Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Head Up Display Switch Replacement (Head Up Display Switch Replacement)
* Control Module References (Programming and Relearning)for the HUD replacement, setup and programming