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

Inspection and verification

1. Check the customer's complaint.

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

Visual check

Electrical equipment:

• Control lamp for glow plugs
• Fuses
• Box 1, under seat fuse box
• Glow Plug Relay
• Engine control relay
• Wiring harness / electrical connectors
• glow plugs
• The engine control unit (ECM)

3. If there is an obvious reason for the problem you identified or described by the client, eliminate it before proceeding to further actions (if possible).

4. Before Referring to the Symptom Table or DTC Index (DTC) read all DTCs with a validated diagnostic system or scan tool. Clear all DTCs after troubleshooting.

Symptom table

sign	Possible reason	Operation
Bad start (extreme weather conditions)	Glow plugs do not work / are not effective enough Fuel temperature too low To reduce this effect, the fuel system recirculates 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 electrical manuals. Check for DTCs (DTC), indicating a malfunction of the glow plugs. Repair if necessary. Clear DTCs and check for proper system operation.
High emissions when engine is cold	Post-heating phase not working	Check the wiring harnesses at the glow plugs and where they connect to the main wiring harness. Refer to electrical manuals. Check for DTCs (DTC), indicating a malfunction of the glow plugs. Repair if necessary. Clear DTCs and check for proper system operation. Post-heating operation is designed for conditions when the engine temperature is below 50°C, the rotation speed does not exceed 2500 rpm, and begins a maximum of 30 seconds after the engine is started.
High noise and vibration levels with a cold engine	Post-heating phase not working	Check the wiring harnesses at the glow plugs and where they connect to the main wiring harness. Refer to electrical manuals. Check for DTCs (DTC), indicating a malfunction of the glow plugs. Repair if necessary. Clear DTCs and check for proper system operation. Post-heating operation is designed for conditions when the engine temperature is below 50°C, the rotation speed does not exceed 2500 rpm, and begins a maximum of 30 seconds after the engine is started.

See section 100-00 for a complete list of DTCs that can be logged in the vehicle. For more information, see: How to use this manual (100-00 General information, Description and principle of operation).