Engine Control System & Fuel System - 4.6l - DTC p2430 to DTC p2544 Cadillac DTS I

Diagnostic Instructions

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information

Typical Scan Tool Data

AIR Pressure Sensor

Circuit/System Description

The secondary air injection (AIR) system aids in the reduction of hydrocarbon emissions during a cold start. The system forces fresh filtered air into the exhaust stream in order to accelerate the catalyst operation. An electric air pump, the secondary AIR injection pump, provides filtered air on demand to the AIR control solenoid valve/pressure sensor assembly. The AIR control solenoid valve/pressure sensor assembly controls the flow of air from the AIR pump to the exhaust manifold. The AIR solenoid relay supplies the current needed to operate the AIR control solenoid valve/pressure sensor assembly. A pressure sensor is used to monitor the air flow from the AIR pump. The ECM supplies the internal pressure sensor with a 5-volt reference, an electrical ground, and a signal circuit.

The AIR diagnostic uses 3 phases to test the AIR system

1. DTCs P0411 and P2430 run during Phase 1
2. DTCs P2430 and P2440 run during Phase 2
3. DTC P2444 runs during Phase 3

During phase 1, both the AIR pump and the solenoid valve are activated. Normal secondary air function occurs. Expect system pressure is 8-10 kPa above BARO.

During phase 2, only the AIR pump is activated. The solenoid valve is closed. Pressure sensor performance and solenoid valve deactivation are tested. Expected system pressure is 10-20 kPa above BARO.

During phase 3, neither the AIR pump nor the solenoid valve is activated. AIR pump deactivation is tested. Expected system pressure equals BARO.

In all 3 phases, testing is accomplished by comparing the measured pressure against the expected pressure. The ECM can detect faults in the AIR pump, AIR control solenoid valve/pressure sensor assembly, and the exhaust check valve. The pressure sensor can also detect leaks and restrictions in the secondary AIR system plumbing.

Conditions for Running the DTC

P2430

1. DTCs P0412, P0418, P0606, P1635, P1639, P2432, P2433 are not set.
2. Greater than 60 minutes has elapsed since the last cold start.
3. The AIR pump is commanded ON.
4. DTC P2430 runs continuously when the above conditions are met.

2431

1. DTCs P0106, P0107, P0108, P0412, P0418, P0606, P0641, P0651, P1635, P1639, P2432, P2433 are not set.
2. The ignition is ON.
3. DTC P2431 runs continuously when the above conditions are met.

2432 and 2433

1. DTCs P0606, P0641, P0651, P1635, P1639 are not set.
2. The ignition is ON or the engine is running.
3. DTC P2432 and 2433 run continuously when the above conditions are met.

The ECM determines that the pressure sensor value change is less than a calibrated value.

P2431

1. The ECM determines that the difference between the AIR pressure sensor and the barometric pressure (BARO) sensor signals is greater than 10 kPa when the AIR pump is commanded OFF. OR
2. The ECM determines that the difference between the AIR pressure sensor and the BARO sensor signals is greater than 50 kPa when the AIR pump is commanded ON.

P2432

The pressure sensor signal is less than 0.2 volt for at least 12.5 seconds.

P2433

The pressure sensor signal is equal to or greater than 4.7 volts for at least 12.5 seconds.

Action Taken When the DTC Sets

DTCs P2430, P2431, P2432, and P2433 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P2430, P2431, P2432, and P2433 are Type B DTCs.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON, verify that the AIR pump is not activated.
2. Ignition ON, observe that the AIR Pressure Sensor parameter approximately equals BARO. If not equal, verify that the BARO reading is correct for your altitude. Refer to «Altitude Versus Barometric Pressure»(/cadillac/dts/i-2005-2011/remont/testing-diagnostics/#engine-control-system-fuel-system-46l-introduction-2-of-2__altitude-versus-barometric-pressure) . If the reading is not correct for your altitude, diagnose the MAP sensor. Refer to «DTC P0106»(/cadillac/dts/i-2005-2011/remont/testing-diagnostics/#engine-control-system-fuel-system-46l-dtc-p0016-to-dtc-p0336) .
3. Engine running, enable the AIR solenoid with a scan tool and observe that the AIR Pressure Sensor parameter equals approximately 10-20 kPa above BARO. If less than the specified range, verify that the AIR pump is activating.
4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the AIR solenoid.
2. Ignition OFF, test for less than 1 ohm of resistance between the low reference circuit terminal 4 and ground. If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 3 and ground. If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM. If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
4. Verify the scan tool AIR Pressure Sensor parameter is less than 0.5 volts. If greater than the specified range, test the signal circuit terminal 2 for a short to voltage. If the circuit tests normal, replace the ECM.
5. Install a 3A fused jumper wire between the signal circuit terminal 2 and the 5-volt reference circuit terminal 3. Verify the scan tool AIR Pressure Sensor parameter is greater than 4.9 volts. If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
6. Ignition OFF, connect all wiring harness connectors.
7. Engine RUNNING, enable the AIR system with a scan tool and observe the AIR Pressure Sensor parameter equals approximately 8-10 kPa above BARO. If not within the specified range, continue with this procedure.
8. Remove the AIR inlet hose from the AIR pump.
9. Engine RUNNING, enable the AIR system with a scan tool and observe the AIR Pressure Sensor parameter equals approximately 8-10 kPa above BARO. If within the specified range, the AIR pump inlet hoses/pipes are restricted. Remove the restriction or replace the hose/pipe. If not within the specified range, continue with this procedure.
10. Disconnect the hose from the AIR pump outlet.
11. Disconnect the hose quick-connect from the AIR solenoid valve inlet.
12. Install a length of standard 1-inch I.D., 25 4-mm, hose from the AIR pump outlet to the AIR solenoid valve inlet.
13. Engine RUNNING, enable the AIR system with a scan tool and observe the AIR Pressure Sensor parameter equals approximately 8-10 kPa above BARO. If within the specified range, the AIR pump outlet hoses/pipes are restricted or leaking. Remove the restriction or replace the hose/pipe. If less than the specified range, replace the AIR pump. If more than the specified range, continue with this procedure.
14. Remove the AIR solenoid valve.
15. Leave the standard hose and harness connector connected.
16. Engine RUNNING, enable the AIR system with a scan tool and observe the AIR Pressure Sensor parameter increases to approximately 7 kPa above BARO. If more than the specified range, replace the AIR solenoid valve. If within the specified range, the AIR solenoid valve outlet pipe or the exhaust system is restricted. Remove the restriction or replace the appropriate component.

Solenoid Valve

Apply appropriately fused battery voltage and ground to the solenoid terminals 6 and 4 and verify that the valve opens and closes completely as voltage is applied to and removed from the solenoid terminals. Observe that the valve is not obstructed or leaking.

1. If the valve operates incorrectly, leaks, or is obstructed, remove the obstruction or replace the AIR solenoid valve.

Repair Procedures

1. «Secondary Air Injection Check Valve Replacement»(/cadillac/dts/i-2005-2011/remont/testing-diagnostics/#engine-control-system-fuel-system-46l-introduction-2-of-2)
2. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup and programming

Repair Verification

1. Engine running, observe that the AIR Pressure Sensor parameter approximately equals BARO.
2. Engine running, enable the AIR pump with a scan tool and observe that the AIR Pressure Sensor parameter equals approximately 20-25 kPa above BARO.
3. Engine running, enable the AIR Solenoid with a scan tool and observe that the AIR Pressure Sensor parameter equals approximately 8-10 kPa above BARO.

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provide an overview of each diagnostic category.

AIR Pressure Sensor

The secondary air injection (AIR) system aids in the reduction of hydrocarbon emissions during a cold start. The system forces fresh filtered air into the exhaust stream in order to accelerate the catalyst operation. An electric air pump, the secondary AIR injection pump, provides filtered air on demand to the AIR control solenoid valve/pressure sensor assembly. The AIR control solenoid valve/pressure sensor assembly controls the flow of air from the AIR pump to the exhaust manifold. The AIR solenoid relay supplies the current needed to operate the AIR control solenoid valve/pressure sensor assembly. A pressure sensor is used to monitor the air flow from the AIR pump. The engine control module (ECM) supplies the internal pressure sensor with a 5-volt reference, an electrical ground, and a signal circuit.

The AIR diagnostic uses 3 phases to test the AIR system

1. DTCs P0411 and P2430 run during Phase 1
2. DTCs P2430 and P2440 run during Phase 2
3. DTC P2444 runs during Phase 3

In all 3 phases, testing is accomplished by comparing the measured pressure against the expected pressure. The ECM can detect faults in the AIR pump, AIR control solenoid valve/pressure sensor assembly, and the exhaust check valve. The pressure sensor can also detect leaks and restrictions in the secondary AIR system plumbing.

1. DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0128, P0201-P0208, P0300, P0351-P0358, P0411, P0412, P0418, P0420, P0606, P0641, P0651, P2430, P2431, P2432, P2433, 2444 are not set.
2. The system voltage is 9-18 volts.
3. The BARO is greater than 70 kPa.
4. The MAF sensor is less than 33 g/s.
5. DTC P2440 runs once per trip start up when the above conditions are met and AIR pump operation is requested.
6. AIR system is commanded ON.
7. Conditions are stable for greater than 5 seconds.

Conditions for Setting the DTC

1. The AIR system does not meet expected pressure conditions.
2. DTC P2440 sets with in 8 seconds when the above conditions are met.

DTC P2440 is a Type B DTC.

DTC P2440 is a Type B DTC.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. If any other Secondary Air Injection System Pressure Sensor Circuit DTCs are set then perform those diagnostics first.
2. Ignition ON, enable and disable the AIR solenoid relay and observe that the solenoid valve operates.
3. Inspect the AIR hoses/pipes between the pump and the shut-off valve for leaks.
4. Engine running, enable the AIR pump relay and observe that the AIR Pressure Sensor parameter increases to approximately 10-20 kPa above BARO.
5. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

1. Disconnect the AIR solenoid valve.
2. Ignition ON, connect a test lamp between the AIR solenoid voltage supply terminal 6 and the solenoid ground circuit terminal 4, the test lamp should not illuminate. If the test lamp illuminates, test the AIR solenoid supply voltage circuit for a short to voltage. If the circuit tests normal, test or replace the AIR solenoid relay.
3. Inspect the AIR pump inlet and outlet hoses/pipes for leaks or restrictions.
4. Inspect the AIR solenoid valve for leaks. If the solenoid valve inspects OK, replace the AIR pump.

AIR Solenoid Static Test

Measure the AIR solenoid for a resistance of 4.8-6.8 ohms across the B+ terminal 6 and the ground terminal 4 at the AIR check valve at an ambient temperature of approximately 20°C (68°F).

1. If the resistance is not within range, replace the AIR check valve assembly.

AIR Solenoid Test

Install a 10A fused jumper wire between the battery voltage supply terminal and 12 volts. Install a jumper wire between ground terminal at the solenoid valve and ground. The AIR solenoid valve should open when the jumper is connected to ground and close when the jumper is removed from ground.

1. If the solenoid valve does not perform as specified, replace the check valve and assembly.

Relay Test

1. Test between the normally closed switch terminals, if any, for 0 ohms.
2. Test between the normally open switch terminals for infinite ohms.
3. Test between each switch terminal and either coil terminal for infinite ohms.
4. Connect the relay coil terminals to ground and fused power to energize the relay.
5. Test between each switch terminal and each coil terminal for 0 volts.
6. Test between the normally closed switch terminals, if any for infinite ohms.
7. Test between the normally open switch terminals for 0 ohms.

1. «Secondary Air Injection Check Valve Replacement»(/cadillac/dts/i-2005-2011/remont/testing-diagnostics/#engine-control-system-fuel-system-46l-introduction-2-of-2)
2. «Secondary Air Injection Pump Replacement»(/cadillac/dts/i-2005-2011/remont/testing-diagnostics/#engine-control-system-fuel-system-46l-introduction-2-of-2)
3. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement and programming

1. Ignition ON, enable and disable the AIR solenoid relay and observe that the check valve operates.
2. Inspect the AIR hoses/pipes between the pump and the shut-off valve for leaks.
3. Engine running, enable the AIR pump relay and observe that the AIR Pressure Sensor parameter increases to approximately 10-20 kPa above BARO.

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provide an overview of each diagnostic category.

AIR Pressure Sensor

The secondary air injection (AIR) system aids in the reduction of hydrocarbon emissions during a cold start. The system forces fresh filtered air into the exhaust stream in order to accelerate the catalyst operation. An electric air pump, the secondary AIR injection pump, provides filtered air on demand to the AIR control solenoid valve/pressure sensor assembly. The AIR control solenoid valve/pressure sensor assembly controls the flow of air from the AIR pump to the exhaust manifold. The AIR solenoid relay supplies the current needed to operate the AIR control solenoid valve/pressure sensor assembly. A pressure sensor is used to monitor the air flow from the AIR pump. The ECM supplies the internal pressure sensor with a 5-volt reference, an electrical ground, and a signal circuit.

The AIR diagnostic uses 3 phases to test the AIR system

1. DTCs P0411 and P2430 run during Phase 1
2. DTCs P2430 and P2440 run during Phase 2
3. DTC P2444 runs during Phase 3

In all 3 phases, testing is accomplished by comparing the measured pressure against the expected pressure. The ECM can detect faults in the AIR pump, AIR control solenoid valve/pressure sensor assembly, and the exhaust check valve. The pressure sensor can also detect leaks and restrictions in the secondary AIR system plumbing.

1. DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0128, P0201-P0204, P0300, P0351-P0358, P0411, P0412, P0418, P0420, P0606, P0641, P0651, P1106, P1107, P2430, P2431, P2432, P2433, 2440 are not set.
2. The system voltage is 9-18 volts.
3. The BARO is greater than 70 kPa.
4. The MAF sensor is less than 33 g/s.
5. DTC P2444 runs once per trip start up when the above conditions are met and AIR pump operation is requested.
6. AIR system is commanded ON.
7. Conditions are stable for greater than 5 seconds.

1. The measured AIR pressure is greater than expected.
2. DTC P2444 sets within 5 seconds when the above conditions are met.

1. The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) at the beginning of the fourth ignition cycle, after 3 ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC and related Freeze Frame data clears after 40 warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. Verify that DTCs P0411, P0418, P0641, P0651, P2432 or P2433 are not set. If any of the DTCs are set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-trouble-code-dtc-list) .
2. Ignition ON, observe that the AIR pump is not activated. If the AIR pump is operating, test the AIR pump voltage supply circuit for a short to voltage. If the circuit tests normal, test the AIR pump relay control circuit for a short to ground. If the circuits test normal, test the AIR pump relay. If the relay and circuits test normal, replace the control module.
3. Ignition ON, enable and disable the AIR pump relay with a scan tool, listen for the AIR pump to turn ON and OFF.
4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Ignition ON, disconnect the AIR pump harness connector. Connect a test lamp between the pump voltage supply circuit terminal A and the pump ground circuit terminal C, observe that the test lamp is not illuminated.

1. If the test lamp is illuminated, test for a short to voltage on the pump voltage supply circuit. If the circuit test normal, replace the AIR pump relay.

Component Testing

AIR Pump Dynamic Test

1. Install a 50A fused jumper wire between the B+ terminal and 12 volts. Install a jumper wire between the ground terminal and ground.
2. Observe for a pressurized air flow at the pump outlet. If a pressurized air flow is not observed, replace the AIR pump.

Relay Test

1. Test between the normally closed switch terminals, if any, for 0 ohms.
2. Test between the normally open switch terminals for infinite ohms.
3. Test between each switch terminal and either coil terminal for infinite ohms.
4. Connect the relay coil terminals to ground and fused power to energize the relay.
5. Test between each switch terminal and each coil terminal for 0 volts.
6. Test between the normally closed switch terminals, if any for infinite ohms.
7. Test between the normally open switch terminals for 0 ohms.

1. «Secondary Air Injection Pump Replacement»(/cadillac/dts/i-2005-2011/remont/testing-diagnostics/#engine-control-system-fuel-system-46l-introduction-2-of-2)
2. «Secondary Air Injection Check Valve Replacement»(/cadillac/dts/i-2005-2011/remont/testing-diagnostics/#engine-control-system-fuel-system-46l-introduction-2-of-2)
3. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for engine control module (ECM) replacement and programming

Ignition ON, observe that the AIR pump is not operating.

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provide an overview of each diagnostic category.

To improve shift feel, the transmission control module (TCM) may request that the engine control module (ECM) reduce engine torque during shift events. When such a request is received, the ECM responds by retarding the base ignition timing and notifying the TCM that the request has succeeded. If the ECM is unable to comply with the request, the ECM sends the TCM a message that the request has failed.

The torque reduction request is sent to the ECM through a communication network called the controller area network (CAN). Two circuits are used to communicate CAN data between the ECM and TCM. A fault in the CAN will not cause DTC P2544 to set by itself. If a CAN fault occurs, other DTCs will set before DTC P2544.

When the TCM receives a torque reduction failure message from the ECM, then DTC P2544 will set. DTC P2544 is a type B DTC.

1. The engine run time is greater than 5 seconds.
2. No other CAN errors are present.

The ECM notifies the TCM that a torque reduction request has failed for 2 seconds.

1. DTC P2544 is a Type B DTC.
2. The TCM commands maximum line pressure.
3. The TCM freezes transmission adaptive functions.
4. At the time of the first failure, the TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as a Failure Record.
5. At the time of the second failure, the ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as a Freeze Frame.
6. The TCM stores DTC P2544 in TCM history.

Conditions for Clearing the DTC

1. DTC P2544 is a Type B DTC.
2. The ECM turns OFF the MIL after the sixth consecutive drive trip in which the TCM does not send a MIL illumination request.
3. A scan tool can clear the DTC.
4. The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without a non emission related diagnostic fault occurring.
5. The TCM cancels the DTC default actions when the ignition is OFF long enough in order to power down the TCM.

Diagnostic Aids

This test procedure requires that the vehicle battery has passed a load test and is completely charged. Refer to Battery Inspection/Test

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Observe the DTCs in the scan tool

1. If DTC P0604 is set, replace the ECM.
2. If DTC P0604 is not set, replace the TCM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM or TCM replacement, programming, and setup.

See also:
• Diagnostic System Check - Vehicle
• Strategy Based Diagnosis
• Diagnostic Procedure Instructions
• Engine Controls Schematics
• Component Connector End Views
• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs
• Powertrain Diagnostic Trouble Code (DTC) Type Definitions
• Control Module References
• Altitude Versus Barometric Pressure
• DTC P0106
• Diagnostic Trouble Code (DTC) List - Vehicle
• Battery Inspection/Test
• Diagnostic Repair Verification