P226B
P226B-TURBOCHARGER BOOST PRESSURE NOT RESPONDING
For a complete wiring diagram, refer to the Wiring Information.
Theory of Operation
The Variable Geometry Turbocharger (VGT) adjusts turbocharger performance by moving the position of the impeller nozzle, on the high-pressure (engine exhaust gas) side of the turbocharger assembly. Desired position of the actuator is commanded from the Powertrain Control Module (PCM). Actual position is sensed by the VGT, and reported back to the PCM as feedback. Discrepancy in position feedback sent to the module, and commanded position sent to the VGT by more than a prescribed amount will result in failure of device rationality diagnostics. Failure to properly actuate the VGT will result in poor engine performance. The PCM lights the MIL lamp after the diagnostic runs and fails in two drive cycles. The PCM will turn off the MIL lamp immediately after this diagnostic runs and passes in four consecutive drive cycles.
- When Monitored:
When the engine is in regeneration of the aftertreatment system.
- Set Condition:
Turbo position is not within the commanded position during desoot or the difference between charge flow and charge flow command is over the calibrated limit.
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.
NOTE: If any other DTCs are present with P2563, address P2563 before attempting to repair other fault codes. If however, DTC P0471 is present along with P2563, both DTCs should be addressed and repaired.
1. VEHICLE CONFIGURATION
1. The repair procedure is different depending on whether the vehicle is a Pick Up or Chassis Cab.
Is the vehicle a Pick Up or Chassis Cab?
Pick Up
- Go To 2
Chassis Cab
- Go To 3
2. TURBOCHARGER CLEANING
1. Use the scan tool to perform the Turbocharger Cleaning procedure.
NOTE: The Turbocharger Cleaning procedure can only run if the P2262, P226B or P2563 are present (active, pending or stored). Do not erase the DTC before attempting to run the procedure.
2. Follow the directions on the scan tool completely. After the test runs it will determine if cleaning of the Turbocharger is necessary. After the cleaning is completed the test will run again and determine if the Turbocharger has been cleaned. The Turbocharger Cleaning procedure will allow up to three attempts to clean the Turbocharger before failing it.
Did the Turbocharger Cleaning procedure pass the Turbocharger as clean?
Pick Up
- Repair complete.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
Chassis Cab
- Replace the Turbocharger Assembly.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
3. OTHER DTCS PRESENT
1. Turn ignition on.
2. With the scan tool, read DTCs.
Are any other Turbocharger related DTCs present?
Yes
- Repair the other Turbocharger related DTCs before proceeding.
No
- Replace the Turbocharger Assembly.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.