PRE-RELEASE
DTC 20 or 21
| DTC 20 or 21 |
| 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 Descriptors |
DTC 20
Parking Heater Glow Plug Circuit Open
DTC 21
Parking Heater Glow Plug Circuit Low or Circuit High
| Diagnostic Fault Information |
| Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
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Heater Glow Plug Supply Voltage Circuit
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21
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20
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21
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-
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Heater Glow Plug Low Reference Circuit
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20
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21
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-
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| Circuit/System Description |
The parking heater uses an auxiliary heater glow plug to increase the temperature in the combustion chamber to a temperature that is necessary to ignite the air fuel mixture. Once a stable flame has formed, the glow plug will turn OFF.
| Conditions for Running the DTC |
Ignition OFF. Battery voltage must be between 10-15 V.
| Conditions for Setting the DTC |
parking heater has recognized out of range condition for more than 2.5 s.
| Action Taken When the DTC Sets |
The parking heater will lock.
| Conditions for Clearing the DTC |
DTC must be cleared with the remote control.
| Reference Information |
Schematic Reference
HVAC Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Fuel Operated Heater 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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| Circuit/System Verification |
Ignition OFF, command the parking heater ON and OFF with the remote control. Verify the parking heater turns ON and OFF with no DTCs.
| Component Testing |
Dynamic Test
| 1. |
Ignition OFF, separate the K87 Parking Heater Control Module from the X150 Parking Heater Harness & Parking Heater Assembly Harness.
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| 2. |
Ignition OFF, test for less than 5 Ω between the E46 Parking Heater Glow Plug low reference circuit terminal and ground.
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| 3. |
If greater than the specified range, replace the K87 Parking Heater Control Module.
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| 4. |
Install a test lamp between the E46 Parking Heater Glow Plug control circuit terminal and low reference circuit terminal.
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| 5. |
Command the parking heater ON and OFF using the remote control. Verify the test lamp turns ON and OFF with each command.
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| 6. |
If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K87 Parking Heater Control Module.
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| 7. |
If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K87 Parking Heater Control Module.
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| 8. |
If all circuits test normal, test or replace the E46 Parking Heater Glow Plug.
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| Repair Instructions |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
