A/T - 4L60E/4L80E, Cold Weather Performance
File In Section: 07 - Transmission/TransaxleBulletin No.: 01-07-30-013
Date: April, 2001
INFORMATION
Subject:
Information On Automatic Transmission Performance During Cold Weather Operation
Models:
1999-2001 Chevrolet and GMC C/K Models
with 4.3 L, 4.8 L. 5.3 L, or 6.0 L Gas Engine
(VINS W, V, T, U - RP0s L35, LR4, LM7, LQ4)
and 4L60-E or 4L80-E Automatic Transmission (M30, MT1)
This bulletin is being revised to add 2000 and 2001 model years. Please discard Corporate Bulletin Number 87-71-76 (Section 7 - Transmission).
Transmission operation during cold weather has been revised on these vehicles to provide faster engine warm-up and improved heater performance. During initial key-up, if intake air temperature (IAT) is less than 0°C (32°F), 2-3 and 3-4 upshift speeds will be affected as detailed below:
2-3 upshift
^ If the throttle position (TPS) is less than 37 percent, the 2-3 upshift will take place at a minimum speed of 32 mph (51 km/h).
^ If the TPS is above 37 percent, the shifts will divert back to the normal shift pattern.
3-4 Upshift
^ If the throttle position (TPS) is less than 37 percent, the 3-4 upshift will take place at a minimum speed of 47 mph (75 km/h).
^ If the TPS is above 37 percent, the shifts will divert back to the normal shift pattern.
TCC Operation
If the transmission fluid temperature is less than 17°C (62.6°F), TCC operation will not occur until the transmission fluid temperature is greater than 20°C (68°F).
When ECT reaches 77°C (171°F), 2-3 and 3-4 upshifts will divert back to the normal shift patterns. A brief description of operation is also included in the Owner's Manual.
DISCLAIMER