Review
Diesel engines have an additional drive belt for the high pressure fuel pump. This section is dedicated to the basic checks of both.
Information about the system and its operation can be found in the appropriate section of the workshop manual.
Inspection and verification
1. Make sure the customer's complaint is valid.
2. Visually inspect for obvious mechanical problems.
Mechanical factors |
3. If an obvious cause of a problem you identified or described by a customer is found, resolve it before proceeding to the next steps (if possible).
WARNING: If the engine is operated without an accessory drive belt, DTCs may be generated to prevent activation of certain components (DTC), to be erased before the vehicle is returned to its owner. The engine should not run with the belts removed for more than 2-3 minutes. Failure to follow this instruction may result in damage to the vehicle.
4. Use an approved diagnostic system or scan tool (tester), to retrieve all DTCs before referring to the Symptom Table DTC Index (DTC).
Clear all DTCs after troubleshooting.
Symptom table (accessory drive belt)
Symptom | Possible reason | Actions |
Noise | Check belt condition (see visual inspection). Check tensioner operation. Check pulley alignment. Check actuated elements for increased resistance to rotation. Repair if necessary. | |
Drive belt not holding tension | Check belt condition (see visual inspection). Check tensioner operation. Repair if necessary. |
Symptom table (high pressure fuel pump belt)
Symptom | Possible reasons | Actions |
Noise | Check belt condition (see visual inspection). Check the belt cover for signs of contamination (this may indicate misalignment of the pump), see the relevant section of the workshop manual. If the belt is removed, the belt tensioner should be replaced by checking the bearing for failure. Remove the belt, check the fastening of the high pressure fuel pump pulley. Check high pressure fuel pump for increased resistance to rotation (increased resistance in the pump causes the pulley lock nut to loosen - this is a design feature). Check for diagnostic trouble codes (DTC), indicating a pump failure. | |
Drive belt not holding tension | Check belt condition (see visual inspection). Check tensioner operation. Repair if necessary. | |
Loss of motion transmission (without transferring motion to the high pressure fuel pump, the engine will not run) | Investigate cause of broken/damaged belt (a break in the belt at a 45 degree angle usually indicates shearing, a break straight across the belt usually indicates that the belt has been pinched). Check high pressure fuel pump for increased resistance to rotation (increased resistance in the pump causes the pulley lock nut to loosen - this is a design feature). Check for diagnostic trouble codes (DTC), indicating a pump failure. |
DTC index
NOTE: Universal Scan Tools cannot read the listed codes 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 problem (the last 2 digits give additional information read by the diagnostic system approved by the manufacturer).
NOTE: See Section 303-14 for a complete list of ECM DTCs "Electronic engine management system" in the workshop manual.
DTCs | Description | Possible reasons | Actions |
P050600 | The speed of rotation of the crankshaft, taking into account the air supply control system in idle mode, is lower than expected | Check the air intake system. Check accessory drive belt and components. Refer to the relevant section in the workshop manual. |
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