Diagnostics and testing Turbocharger (Discovery 3)

Inspection and verification

CAUTION: The following checks may require working near hot parts. Wear appropriate protective equipment. Failure to follow this instruction may result in personal injury.

CAUTION: The turbocharger may continue to rotate after the engine has stopped. Do not attempt to check the turbocharger until at least one minute has passed since the engine has been turned off. Failure to do so could result in personal injury.

1. Accurately define the problem stated by the customer.

2. Visually inspect for obvious mechanical and electrical faults.

Mechanical elements	Electrical elements
Air intake system Hose(s)/hose connections Turbocharger General condition of the engine.	Electrical circuit(s) Turbocharger drive Engine Control Module (ECM) Electrical connectors and wiring harnesses

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

4. Before referring to the symptom chart or DTC index, read all diagnostic trouble codes (DTCs) using an approved diagnostic system or scan tool.

Clear all DTCs after troubleshooting.

Table of signs of malfunction

Sign of malfunction	Possible reason	Action taken
Poor dynamic performance	Low fuel level/contamination Clogged air intake system General condition of the engine ECM failure	Check the fuel level and condition. Check the air intake system for any blockages. Check engine condition, compression, etc. Check for DTC diagnostic trouble Codes If an ECM fault is suspected, refer to the Warranty Service Policies and procedures manual.
No boost	Electrical connectors and wiring harnesses Clogged air intake system Charge air cooler is clogged/leaking Turbocharger drive failure Turbocharger failure ECM failure	Check electrical connectors and wiring harnesses. Check the air intake system for blockages/leaks (see "Visual Inspection"). For air intake system tests. Check turbocharger actuator and electrical circuits. Refer to electrical manuals. Check turbocharger mechanical condition. If ECM malfunction is suspected, refer to the Warranty Policy and Procedures Manual.
No boost/excessive noise	Turbocharger failure	Disconnect the intake and exhaust manifolds and manually rotate the turbocharger shaft. Any difficulty in rotating smoothly indicates a fault. Check the turbocharger shaft for any lateral movement. Excessive movement indicates a fault. If in doubt, compare the suspect unit to the new turbocharger unit.

DTC indicator

NOTE: Generic scan tools may not be able to read the codes listed or may only be able to 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 an approved diagnostic system).

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

DTC	State	Possible reasons	Action taken
P004500	Turbocharger/Supercharger Boost Sensor A Circuit - Open Circuit	Variable Geometry Turbocharger (VGT) Actuator Circuit High Resistance VGT actuator circuit: short to ground VGT actuator malfunction ECM failure	Refer to the electrical manual and check the VGT electrical circuit. If you have any doubts about the module's functionality, refer to the warranty policy and procedures manual.
P004600	Turbocharger/Mechanical Compressor Control Circuit A Range/Performance Problems	Variable Geometry Turbocharger (VGT) Actuator Circuit High Resistance VGT actuator circuit: short to ground VGT actuator circuit: short circuit to battery + VGT actuator malfunction ECM failure	Refer to the electrical manual and check the VGT electrical circuit. If you have any doubts about the module's functionality, refer to the warranty policy and procedures manual.
P004700	Turbocharger/Supercharger Boost Sensor A Circuit Low Voltage	Variable Geometry Turbocharger (VGT) Actuator Circuit High Resistance VGT actuator circuit: short to ground VGT actuator malfunction ECM failure	Refer to the electrical manual and check the VGT electrical circuit. If you have any doubts about the module's functionality, refer to the warranty policy and procedures manual.
P004800	Turbocharger/Supercharger Boost Sensor A Circuit High Voltage	VGT actuator circuit: short circuit to battery + VGT actuator malfunction ECM failure	Refer to the electrical manual and check the VGT electrical circuit. If you have any doubts about the module's functionality, refer to the warranty policy and procedures manual.
P023400	Turbocharger/Mechanical Compressor A Boost Pressure Too High	Air leak Manifold Absolute Pressure (MAP) Sensor Circuit High Resistance MAP Sensor Circuit Short to Ground MAP sensor electrical circuit: short circuit to battery + MAP sensor malfunction Exhaust Gas Recirculation (EGR) System Malfunction VGT actuator malfunction	Refer to the appropriate section in the workshop manual. Check the MAP sensor and electrical circuits. Refer to the electrical manuals. EGR valve tests are described in the appropriate section of the workshop manual. Check for DTCs indicating a faulty EGR or VGT actuator. If in doubt about the module, refer to the warranty policy and procedures manual.
P029900	Turbocharger/Mechanical Compressor A Boost Pressure Too Low	Air leak after turbocharger MAP Sensor Circuit High Resistance MAP Sensor Circuit Short to Ground MAP sensor electrical circuit: short circuit to battery + MAP sensor malfunction Exhaust Gas Recirculation (EGR) System Malfunction VGT malfunction ECM failure	Refer to the appropriate section in the workshop manual. Check the MAP sensor and electrical circuits. Refer to the electrical manuals. EGR valve tests are described in the appropriate section of the workshop manual. Check for DTCs indicating a faulty EGR or VGT actuator. If in doubt about the module, refer to the warranty policy and procedures manual.
P226300	Turbocharger/Compressor Boost System - Operating Parameters	Air leak after turbocharger Intake Air Temperature (IAT) Sensor Circuit High Resistance, Short to Ground, Short to Power Manifold Absolute Pressure (MAP) Sensor Circuit High Resistance, Short to Ground, Short to Battery Mass Air Flow (MAF) Sensor Circuit High Resistance, Short to Ground, Short to Battery Exhaust Gas Recirculation (EGR) Circuit High Resistance, Short to Ground, Short to Power VGT actuator malfunction Seized turbocharger blades	Check the mechanical condition of the turbocharger and linkage. Check the condition of the air intake system, repair as necessary. Check for sensor DTCs. Check the IAT and MAP sensor circuits. Refer to the electrical manual and repair as necessary. Using the data logger function, check the turbocharger actuator position. Turn the ignition on, turn the engine off and command the turbocharger actuator to 95% PWM, then to 5% PWM and check the turbocharger actuator position again. The angle at 5% PWM should be in the range of 0 - 20%, and at 95% - in the range of 80 - 95%. If not, install a new turbocharger. Clear the DTCs and check for proper operation.