Diagnostics and testing 4.4L (Discovery 3)

Review

Turbocharged engines have 2 accessory drive belts.; this section describes basic checks for both.

For ease of identification, these 2 belts are referred to as the primary and secondary accessory drive belts.

Further information on the system and its operation can be found in the relevant section of the service station manual.

Inspection and verification

1. Check the validity of the customer's complaint.

2. Visually inspect for obvious mechanical problems.

Mechanical factors

Primary drive belt condition (cracking/damage/contamination) Secondary drive belt condition (cracking/damage/contamination) Belt tension Alignment of pulley position Coolant pump Primary tensioner assembly Air conditioning compressor Power steering pump Crankshaft pulley Generator Dynamic Reaction Pump Pulley Tension pulley Turbocharger pulley Secondary tensioner assembly Coolant pump pulley

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

CAUTION: If the engine is run without the accessory drive belt 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 follow this instruction 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

Sign of malfunction	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.

DTC Index

NOTE: Generic scan tools cannot read the codes listed or can only read 5-digit codes. Match the 5 digits from the scan tool with the first 5 digits of the listed 7-digit code to identify the fault. (the last 2 digits provide additional information readable by a manufacturer approved diagnostic system).

NOTE: For a complete listing of ECM DTCs, refer to Section 303-14, Electronic Engine Control System, in the service manual.

DTC	Description	Possible reason	Operation
P050600	Crankshaft speed with air supply management system in idle mode is lower than expected	Reducing the air intake capacity Auxiliary drive overload (defective/sticking element)	Check the air intake system. Check the accessory drive belt and components. Refer to the relevant section of the workshop manual.