:  Dec 17, 2007



Overview

There is an additional drive belt on diesel engines for the fuel injection pump, this section covers basic checks for both.

For information on the description and operation of the system, refer to the relevant workshop manual section.

Inspection and verification

. Verify the customer concern.

. Visually inspect for obvious mechanical faults.

Mechanical
  • Drive belt condition (cracking/damage/contamination)
  • Idler assembly
  • Generator
  • Engine cooling fan
  • Tensioner assembly
  • Engine coolant pump
  • Power steering pump
  • Air conditioning (A/C) compressor
  • Torsional vibration damper
  • Dynamic response pump
  • Tensioner assembly
  • Accessory drive belt
  • Security/Correct installation of the fuel injection pump cover
  • Fuel injection pump belt condition (cracking/damage/contamination)
  • Fuel injection pump belt tensioner assembly
  • Fuel injection pump
  • Fuel injection pump belt

. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.

  : If the engine is run without the accessory drive belts connected to eliminate driven components, diagnostic trouble codes, (DTCs) may be set which must be cleared before the vehicle is returned to the owner. The engine should not be run for more than 2-3 minutes with the belts disconnected. Failure to follow this instruction may result in damage to the vehicle.

. Use the approved diagnostic system or a scan tool to retrieve any DTCs before moving onto the symptom chart or DTC index.
  Make sure that all DTCs are cleared following rectification.
Make sure that all DTCs are cleared following rectification.

Symptom chart (accessory drive belt)

Symptom Possible cause Action
Noise
  • Belt condition
  • Belt tension
  • Pulleys misaligned
  • Driven components (including tensioners)
Check the belt condition (see visual inspection). Check the tensioner function. Check the pulley alignment. Check the driven components for excessive resistance to rotation. Rectify as necessary.
Drive belt does not hold tension
  • Belt condition
  • Tensioner fault
Check the belt condition (see visual inspection). Check the tensioner function. Rectify as necessary.

Symptom chart (fuel injection pump belt)

Symptom Possible causes Action
Noise
  • Belt condition
  • Belt fouling cover
  • Tensioner bearing failure
  • Fuel injection pump failure
Check the belt condition (see visual inspection). Check the belt cover for indications of fouling (this may indicate a pump misalignment), refer to the relevant workshop manual section. The belt tensioner must be renewed if the belt is removed, making a check of the bearing impractical. Remove the belt, check the fuel injection pump pulley for security. Check the fuel injection pump for excessive resistance to rotation (excessive resistance in the pump will cause the pulley securing nut to loosen as a design feature). Check for diagnostic trouble codes (DTCs) indicating a pump malfunction.
Drive belt does not hold tension
  • Belt condition
  • Tensioner fault
Check the belt condition (see visual inspection). Check the tensioner function. Rectify as necessary.
Loss of drive (with no drive to the fuel injection pump, the engine will not run)
  • Belt broken/stripped teeth
  • Drive pulleys loose
Investigate the cause of the belt breakage/damage (a belt broken at a 45 degree angle normally indicates a shear, a break straight across the belt normally indicates that the belt has been crimped). Check the fuel injection pump for excessive resistance to rotation (excessive resistance in the pump will cause the pulley securing nut to loosen as a design feature). Check for DTCs indicating a pump malfunction.

DTC index

:
  Generic scan tools may not read the codes listed, or may read only 5-digit codes. Match the 5 digits from the scan tool to the first 5 digits of the 7-digit code listed to identify the fault (the last 2 digits give extra information read by the manufacturer-approved diagnostic system).

:
  For a full list of ECM DTCs, refer to workshop manual section 303-14 - Electronic Engine Controls.

DTC Description Possible causes Action
P050600 Idle Air Control System RPM Lower Than Expected
  • Air intake restriction
  • Accessory drive overload (defective/seized component)
Check the air intake system. Check the accessory drive belt and components. Refer to the relevant workshop manual section.