4L60-E/4L65-E Automatic Transmission Second Gear Start, Lack/Loss of Power When Accelerating from a Stop (Reprogram Powertrain Control Module (PCM))
| Subject: | 4L60-E/4L65-E Automatic Transmission Second Gear Start, Lack/Loss of Power When Accelerating From a Stop (Reprogram Powertrain Control Module (PCM) |
| Models: | 2004-2005 Cadillac Escalade |
| 2004-2005 Chevrolet Avalanche, Express, Silverado, Suburban, Tahoe |
| 2004-2005 GMC Savana, Sierra, Yukon |
| 2004-2005 HUMMER H2 |
| with 4L60-E (RPO M30) or 4L65-E (RPO M32) Automatic Transmission |
Condition
Some customers may comment on a slip on launch, low power on a launch or a second gear start when accelerating from a stop.
This condition is usually very intermittent, occurring only once in a few thousand miles of driving.
A Tech 2 or VDR snapshot of the event may show 2nd gear being commanded for approximately two seconds, then 1st gear commanded as would be expected.
Cause
This condition may be caused by an intermittent VSS signal, which causes the PCM to command second gear.
Important: There are other conditions that can cause the transmission to start in a gear higher than first. The following are a few of these conditions.
• Some DTCs can cause the transmission to start in a higher gear. Check for the presence of DTCs and repair as appropriate before proceeding. • Debris on top of the spacer plate or in the valve body or a leaking shift solenoid can cause a 4L60-E or 4L65-E transmission to start in a gear higher than first. A start in a higher gear caused by any of these conditions typically occurs with much
greater frequency. Refer to Service Bulletin 01-07-30-036D or newer for diagnostic information of these conditions. • Placing the shift lever in the D2 position will cause a 4L60-E or 4L65-E transmission to start in second gear.
Correction
- Using a scan tool, check for the presence of DTCs. If DTCs are present, refer to the appropriate SI Document before proceeding with this calibration.
- Technicians are to reprogram the PCM with an updated software calibration. This new service calibration was released with TIS satellite data update version 5 or later available May 1, 2005. Refer to Service Programming System (SPS) in Vehicle Control Systems in the appropriate SI Document.
Important:
• This bulletin ONLY applies to 2004-2005 models year vehicles listed above. • Some DTCs can cause the transmission to start in a higher gear. Check for the presence of DTCs and repair as appropriate before proceeding.
Important: These calibrations also contain the 2-3 shift clunk calibration as detailed in bulletin 05-07-30-012.
Warranty Information
For vehicles repaired under warranty, use:
Labor Operation | Description | Labor Time |
|---|---|---|
J6355 | Module, Powertrain Control - Transmission Reprogramming | Use Current Published Labor Time |
