A/T Controls - Harsh 4-3 Downshift/DTC P1884 Set

# 05-07-30-020A: Automatic Transmission 4-3 Shift Malfunction or 4-3 Harsh Downshift, Diagnostic Trouble Code (DTC) P1884 Set (Reprogram Transmission Control Module (TCM)) - (Jul 1, 2011)

Automatic Transmission 4-3 Shift Malfunction or 4-3 Harsh Downshift, Subject: Diagnostic Trouble Code (DTC) P1884 Set (Reprogram Transmission Control Module (TCM))

Models:
2004-2005 Chevrolet Optra
with ZF-4HP 16 Automatic Transmission

This bulletin is being revised to add DTC information to the title line. Please discard Corporate Bulletin Number 05-07-30-020 (Section 07 - Transmission/Transaxle).

Condition
Some customers may comment on the Malfunction Indicator Lamp (MIL) being illuminated or a 4-3 harsh downshift.

Technicians may find DTC P1884 (4-3 gear shift malfunction) set.

Correction
Reprogram the TCM with the modified TCM calibration that has been released to correct both the DTC and the 4-3 harsh downshift. Modifications to the calibration are as follows:

^ Calibration change to reduce the sensitivity of 4-3 error detection.

^ Calibration change in adaptation window and pressure for 4-3 harsh shift improvement.

Important:
The TCM will store a P0703 every time the TCM is energized. Once the TCM sees the brake switch transition from "Released" to "Applied," with the ignition switch On, then the P0703 will be cleared. If the Scan Tool is displaying the P0703 DTC, ensure that you press and release the brake before using the following diagnostic procedure. Only use the diagnostic procedure if the P0703 DTC is not cleared after initially pressing and releasing the brake pedal.

Service Procedure

1. Reprogram the TCM with service software and calibration that is included in TIS data version 8.00 broadcast to dealers via GM Access on August 7, 2005 and on TIS 2000 CD-ROM version 8.0 available August 2005. Refer to SI Document 1D 1672261.

2. Check any Diagnostic Trouble Code in the TCM and ECM and then clear any stored DTCs.

3. Use a scan tool to reset the TCM Adaptation Value.





Calibration Information
The service software and calibration is included in TIS data version 8.00 broadcast to dealers via GM Access on August 7, 2005 and on TIS 2000 CD-ROM version 8.0 available August 2005.





Warranty Information
For vehicles repaired under warranty use the above chart.




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