Diagnostics and testing of the glow plug system (Defender 2007+)

Inspection and verification

1. Check the customer complaint.

2. Visually inspect for obvious signs of mechanical or electrical damage.

Visual inspection

Electrical equipment:

• Glow plug indicator light
• Fuses and fuses
• Insert 1, Under-seat fuse box
• Glow Plug Relay
• Engine control relay
• Wiring harness/electrical connectors
• Glow plugs
• Engine Control Module (ECM)

3. If an obvious cause for the problem you identified or the customer described is found, resolve it before proceeding with further actions (if possible).

4. Before referring to the symptom chart or diagnostic trouble code (DTC) index, read all DTCs with a validated diagnostic system or scan tool. Clear all DTCs after troubleshooting.

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Table of signs of malfunction

Sign	Possible reason	Operation
Bad start (extreme weather conditions)	Glow plugs not working/not effective enough Fuel temperature too low To reduce this effect, the fuel system recirculates the fuel until operating temperature is reached.	Check the wiring harnesses at the glow plugs and where they connect to the main wiring harness. Refer to the electrical manuals. Check for diagnostic trouble codes (DTCs) indicating a malfunction of the glow plugs. Repair as necessary. Clear the DTCs and test the system for proper operation.
High emissions when engine is cold	The post-heating phase does not work	Check the wiring harnesses at the glow plugs and where they connect to the main wiring harness. Refer to the electrical manuals. Check for diagnostic trouble codes (DTCs) indicating a faulty glow plug. Repair as necessary. Clear the DTCs and check for proper system operation. Afterglow operation is designed for conditions when the engine temperature is below 50°C, the engine speed does not exceed 2500 rpm, and begins a maximum of 30 seconds after the engine is started.
High levels of noise and vibration when the engine is cold	The post-heating phase does not work	Check the wiring harnesses at the glow plugs and where they connect to the main wiring harness. Refer to the electrical manuals. Check for diagnostic trouble codes (DTCs) indicating a faulty glow plug. Repair as necessary. Clear the DTCs and check for proper system operation. Afterglow operation is designed for conditions when the engine temperature is below 50°C, the engine speed does not exceed 2500 rpm, and begins a maximum of 30 seconds after the engine is started.

For a complete list of diagnostic trouble codes that may be stored in the vehicle, see Section 100-00. For additional information, refer to: How to Use This Manual (100-00 General information, Description and operating principle).