Diagnostics and checks of accessory drive (Defender 2007+)

Inspection and verification

1. Check the customer complaint.

2. Visually inspect for obvious mechanical faults.

Visual inspection

Mechanical elements:

• Drive belt condition (cracking/damage/contamination)
• Intermediate pulley assembly
• Generator
• Engine cooling fan
• Tensioner assembly
• Engine cooling system pump
• Power steering pump
• Air conditioning (A/C) compressor
• Torsional vibration damper
• Drive belt

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

CAUTION: If the engine is run without the accessory drive belt in order to avoid activating certain components, diagnostic trouble codes (DTCs) may be generated and should be cleared before returning the vehicle to the owner. The engine should not be run for more than 2-3 minutes with the belts removed. Failure to do so may result in vehicle damage.

4. Use the approved diagnostic system or scan tool to retrieve all diagnostic trouble codes (DTCs) before referring to the Symptom Chart or DTC Index.

• Clear all DTCs after troubleshooting.

Table of signs of malfunction (accessory drive belt)

Sign	Possible reason	Operation
Noise	Belt condition Belt tension Skewed pulleys Elements driven by (including tensioners)	Check the condition of the belt (see visual inspection). Check the operation of the tensioner. Check the pulley alignment. Check the driven elements for increased resistance to rotation. Repair if necessary.
The drive belt does not hold tension	Belt condition Tensioner malfunction	Check the condition of the belt (see visual inspection). Check the operation of the tensioner. Repair if necessary.

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).