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 Fuel Pump and Level Sensor Assembly - Primary
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 Control Module References for scan tool information
Circuit/System Verification
1. Ignition ON.
2. Verify 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. while rotating the Head-Up Display dim select switch from the minimum to maximum positions.
• If scan tool parameters do not respond properly
Refer to Circuit/System Testing.
• If scan tool parameters respond properly
3. All OK.
Circuit/System Testing
1. Ignition OFF, disconnect the S27 Head-Up Display Switch.
2. Verify the scan tool Dim Select Switch parameter displays Open.
• If Dim Select Switch parameter does not display Open
1. Ignition OFF, disconnect the harness connector at the Head-Up Display.
2. Test for infinite resistance between the signal circuit terminal 3 and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the P29 Head-Up Display.
• If Dim Select Switch parameter displays Open
3. Test or 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. Turn the dimming switch to minimum position.
2. Test for 25-40 ohms between the signal terminal 3 and the low reference circuit terminal 1.
• If less than 25 ohms or more than 40 ohms
Replace S27 Head-Up Display Switch.
• If 25-40 ohms
3. Turn the dimming switch to the maximum position.
4. Test for 875-950 ohms between the signal terminal 3 and the low reference circuit terminal 1.
• If less than 875 ohms or more than 950 ohms
Replace S27 Head-Up Display Switch.
• If 875-950 ohms
5. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Head-Up Display Replacement Head-Up Display Replacement
* Head-Up Display Dimmer Switch Replacement Head-Up Display Dimmer Switch Replacement
* Control Module References Control Module References for instrument cluster replacement, programming and setup