B3634
DTC B3634
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions)provides an overview of each diagnostic category.
DTC Descriptor
DTC B3634 02
- Head-Up Display Dimming Switch Circuit Short to Ground
Diagnostic Fault Information
Circuit/System Description
The head-up display dimming switch is a resistance ladder switch and wired to head-up display. The head-up display dimming switch signal circuit is pulled up to battery voltage in the head-up display. The head-up display also provides the head-up display switch with a low reference. The head-up display switch is a momentary contact switch that connects a series of resistors in a resistor ladder format. The head-up display monitors the head-up display dimming switch signal circuit to determine the head-up display dimming state. Each switch state corresponds to a certain resistance value.
Conditions for Running the DTC
* The ignition is in OFF, ACCESSORY or RUN position.
* The system voltage is between 9-16 V.
Conditions for Setting the DTC
B3634 02
The head-up display detects that the head-up display switch signal circuit is less than 100 mV.
Action Taken When the DTC Sets
B3634 02
The head-up display will be set in a default illumination level.
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 Schematics (Head Up Display Schematics)
Connector End View Reference
Component Connector End Views (Connector End Views By Name)
Description and Operation
Head Up Display Description and Operation (Description and Operation)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing For Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
Scan Tool Reference
Control Module References (Programming and Relearning)for scan tool information
Circuit/System Verification
Ignition ON, verify that when the head-up display dimming switch is change for minimum to maximum position the scan tool Display Dimming parameter changes from 0% to 100% and the and the scan tool Dim Select Switch parameter changes from 1-12.
Circuit/System Testing
1. Ignition OFF, disconnect the S27 head-up display switch. Verify the scan tool Dim Select Switch parameter displays Open.
• If not the specified value, test the switch signal circuit terminal 3 for a short to ground. If the circuit tests normal, replace the K78 head-up display module.
2. If all circuits tests normal, replace the S27 head-up display switch.
Component Testing
Static Test
1. Ignition OFF, disconnect the harness connector at the S27 Head-Up Display Switch.
2. Turn the dimming switch to minimum position.
3. Test for 25-40 ohm between the signal terminal 3 and the low reference circuit terminal 1. Turn the dimming switch from minimum to maximum and verify the resistance increases in each position to 875-950 ohm in maximum position.
• If the resistance does not change, replace the S27 Head-Up Display Switch.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Instrument Cluster Head-Up Display Replacement (Instrument Cluster Head-Up Display Replacement)
* Instrument Cluster Head-Up Display Dimmer Switch Replacement (Instrument Cluster Head-Up Display Dimmer Switch Replacement)
* Control Module References (Programming and Relearning)for instrument cluster replacement, programming and setup