For 1990-2009 cars

# 4T45 Transmission, MIL/SES On, DTC P1818, Power Door Locks,Cruise Control, Shift Interlock or Retractable Hardtop Inop, Engine Speed Revs Limited, Hybrids-Autostop, Regen or Boost Inop (Reprogram TCM)

Subject: | 4T45 Transmission, MIL/SES On, DTC P1818, Power Door Locks, Cruise Control, Shift Interlock or Retractable Hardtop Inoperative, Engine Speed Revs Limited, Hybrids-Autostop, Regen or Boost Inoperative (Reprogram TCM)

Models: | 2007 Chevrolet Cobalt, HHR, Malibu

| 2007 Pontiac G5, G6

| 2007 Saturn AURA, ION, VUE, VUE Hybrid

| with 4T45 Automatic Transmission (RPOs MN5, ME7)

This bulletin is being revised to remove the 2006 model year. Please discard Corporate Bulletin Number 07-07-30-005A (Section 07-Transmission/Transaxle).

### Condition

Some customers may comment on the illumination of the Malfunction Indicator Lamp (MIL) or the Service Engine Soon (SES) light, the power door locks, cruise control, shift interlock, retractable hardtop being inoperative and engine speed revs limited to 4,000 RPM in first gear after a cold start or cold soak with temperatures between 0° to 10°C (32°F to 50°F).

Customers with hybrid vehicles may also comment on the following conditions:

-- Hybrid Autostop, regen or boost inoperative

### Cause

These conditions may be caused by the TCM setting a false DTC P1818 (Transmission Fluid Pressure (TFP) Valve Position Switch Indicates Drive without Drive Ratio).

### Correction

Verify the conditions and reprogram the transmission control module (TCM) with the new updated calibration using the procedure below.

1. Check for DTCs.
2. Clear DTC P1818.
3. Start the engine.
4. Apply the brake pedal.
5. Place the transmission in reverse.
6. With a Tech 2®, monitor the transmission fluid pressure (TFP) switch parameter.

• | If the TFP parameter indicates Reverse, reprogram the TCM with the updated calibration.

• | If the TFP parameter indicates Park/Neutral, refer to DTC P1818 in SI for further diagnosis.

Important: Confirm the newest calibration includes the "false P1818 fix".

An updated TCM calibration is now available to address this concern. This calibration, or any that follow, is designed to address this concern. Reprogram the TCM with the software now available in the TIS2WEB using the Service Programming System (SPS).

If you cannot access the calibration, call the Techline Customer Support Center at 1-800-828-6860 (English) or 1-800-503-3222 (French) and it will be provided. As always, make sure your Tech 2® Diagnostic Scan Tool is updated with the latest software version.

Clear any codes and verify the condition has been fixed.

### Warranty Information

For vehicles repaired under warranty, use:

Labor Operation | Description | Labor Time
--- | --- | ---
K5364 | Transmission Control Module Transmission Reprogramming with SPS | Use Published Labor Operation Time