Check Engine Light Illuminated, DTC P0400 Set (Reprogram ECM)

Under certain circumstances, some customers may comment that the Check Engine Light is illuminated. Upon investigation, the technician may find DTC P0400 - EGR System Performance set. The vehicle may or may not experience a driveability concern when the Check Engine light is illuminated.

A new calibration has been released to correct this condition. Reprogram the Engine Control Module (ECM) with the software/calibrations contained in GMNAO TIS version 9.0 or later or the Isuzu Technical Communication System (ITCS) CV#15 or later.

Important: This calibration was applied to production starting at the following VIN breakpoints. Do NOT reprogram vehicles at or after these breakpoints for the above-described condition.

Reprogramming 5.2L Denso Controller -- Remote Programming

Remote programming indicates that the software/calibrations can be downloaded to the Scan Tool from the TIS terminal. The Scan Tool is then taken to the vehicle and the software and calibrations are downloaded to the ECM.

Important: Do not use this procedure if the ECM is being replaced. Refer to the Engine Control module (ECM) Replacement procedure found in the 2005MY Service Information CD part # NPD05-ESM-C02.

Important: The following information will NOT be modified during this procedure.

•	Injector Flow Rates

•	Power Takeoff Options (if applicable)

•	Cruise Control Options

•	Exhaust Brake Options

•	Vehicle Speed Limit

1. Retrieve Service Programming information from the ECM using the Tech 2. Follow this navigation: F1: Service Programming System>F0: Request Info.
2. Confirm that the correct VIN is displayed on the Scan Tool.
3. Turn OFF the Scan Tool.
4. Turn OFF the ignition.

Important: If the ABS Class 2 communication is not stopped, the Class 2 bus traffic will be too high and the ECM will not program.

5. Disconnect the ABS module (EHCU) (refer to Corporate Bulletin Number 04-05-25-004) OR remove the Gauges 10A fuse that supplies ignition voltage to the ABS module. This fuse is a hidden fuse located behind the glove box.
6. In the TIS application, select Service Programming System.
7. Select the following information:

•	Select Diagnostic Tool - Tech 2.

•	Select Programming Process - Reprogram ECU.

•	Select ECU Location - Vehicle.

Important: Do not use a ribbon cable longer than 7.62 m (25 ft) or programming errors may occur.

8. Follow TIS prompts to download the new calibration to your Tech 2. Be sure to enter the full 17-digit VIN if not correctly displayed.
9. When completed, turn OFF the Scan Tool and return to the vehicle.

Important: Make sure the batteries are fully charged. Do NOT connect a battery charger during ECM programming.

10. Turn the ignition switch to the ON position with the engine off.
11. Connect the Scan Tool to the vehicle, ensuring a robust connection at the data link connector (DLC), and then turn the Scan Tool ON.
12. At the Main Menu, follow this navigation: F1: Service Programming System>F1: Program ECU then select F1: Program ECU.

Important: If the VIN is not correct, the entire process must be repeated.

13. After ensuring that the VIN is correct, press continue.
14. The ECM is now being reprogrammed. After the Scan Tool displays Programming Was Successful, turn OFF the ignition and the Scan Tool.
15. Install the Gauges 10A fuse or reconnect the ABS module harness connector.
16. Turn the ignition switch to the ON position with the engine off.
17. Use the Scan Tool to clear the DTCs in the TCM. A U2100 TCM DTC will set during the reprogramming.
18. Start the engine and recheck for DTCs.

The ECM programming is complete.

For vehicles repaired under warranty, use: