PRE-RELEASE
DTC B3634
| DTC B3634 |
| Diagnostic Instructions |
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Perform the
Diagnostic System Check - Vehicle
prior to using this diagnostic procedure.
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Review
Strategy Based Diagnosis
for an overview of the diagnostic approach.
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Diagnostic Procedure Instructions
provides an overview of each diagnostic category.
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| DTC Descriptor |
DTC B3634 02
Head-Up Display Dimming Switch Circuit Short to Ground
| Diagnostic Fault Information |
| Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
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Head-Up Display Dimming Switch Signal
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B3634 02
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Low Reference
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1
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1. Head-Up Display Switch Malfunction
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| 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 |
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The ignition is in OFF, ACCESSORY or RUN position.
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The system voltage is between 9-16 V.
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| 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
Connector End View Reference
Component Connector End Views
Description and Operation
Head Up Display Description and Operation
Electrical Information Reference
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Circuit Testing
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Connector Repairs
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Testing for Intermittent Conditions and Poor Connections
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Wiring Repairs
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Scan Tool Reference
Control Module References
| 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 harness connector at the S27 Head-Up Display Switch.
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| 2. |
Test for less than 5 Ω between the low reference circuit terminal 1 and ground.
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| 3. |
If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K78 Head-Up Display Module.
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Ignition ON, verify the scan tool Dim Select Switch parameter is 12.
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If less than the specified range, test the signal circuit terminal 3 for a short to ground. If the circuit tests normal, replace the K78 Head-Up Display Module.
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Install a 3 A fused jumper wire between the signal circuit terminal 3 and the low reference circuit terminal 1. Verify the scan tool Dim Select Switch parameter is 1.
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If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K78 Head-Up Display Module.
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| 8. |
If all circuits test normal, test or replace the S27 Head-Up Display Switch.
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| Component Testing |
Static Test
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Ignition OFF, disconnect the harness connector at the S27 Head-Up Display Switch.
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| 2. |
Turn the dimming switch to minimum position.
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| 3. |
Test for 25-40 Ω 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 Ω in maximum position.
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If the resistance does not change, replace the S27 Head-Up Display Switch.
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| Repair Instructions |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
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Instrument Cluster Head-Up Display Replacement
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Instrument Cluster Head-Up Display Dimmer Switch Replacement
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Control Module References
for instrument cluster replacement, setup and programming
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