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DTC 20 or 21

DTC 20 or 21

Diagnostic Instructions


• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• Diagnostic Procedure Instructions provides an overview of each diagnostic category.


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
Heater Glow Plug Supply Voltage Circuit

21

20

21

-

Heater Glow Plug Low Reference Circuit

-

20

21

-



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


• Circuit Testing

• Connector Repairs

• Testing for Intermittent Conditions and Poor Connections

• Wiring Repairs


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.

2. Ignition OFF, test for less than 5 Ω between the E46 Parking Heater Glow Plug low reference circuit terminal and ground.

3. If greater than the specified range, replace the K87 Parking Heater Control Module.

4. Install a test lamp between the E46 Parking Heater Glow Plug control circuit terminal and low reference circuit terminal.

5. Command the parking heater ON and OFF using the remote control. Verify the test lamp turns ON and OFF with each command.

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.

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.

8. If all circuits test normal, test or replace the E46 Parking Heater Glow Plug.


Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.