| Subject: | 2-3, 3-4 Shift Characteristics During Cold Weather Operation
on 4L60-E or 4L80-E Transmission |
| Models: | 1999-2000 Chevrolet and GMC C/K Models |
| 1999-2000 Cadillac Escalade |
| with 4.3L, 4.8L, 5.3L, or 6.0L Gas Engine (VINs W, V, T, U -- RPOs
L35, LR4, LM7, LQ4) |
| and 4L60-E or 4L80-E Automatic Transmission |
This bulletin is being revised to update the model years. Please discard
Corporate Bulletin Number 01-07-30-013 dated April,
2001 (Section 07 -- Transmission/Transaxle).
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 (TP) is less than 37 percent,
the 2-3 upshift will take place at a minimum speed of 51 km/h (32 mph). |
| • | If the TP is above 37 percent, the shifts will divert back
to the normal shift pattern. |
3-4 Upshift
| • | If the throttle position (TP) is less than 37 percent,
the 3-4 upshift will take place at a minimum speed of 75 km/h (47 mph). |
| • | If the TP 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),
torque converter clutch (TCC) operation will not occur until the transmission
fluid temperature is greater than 20°C (68°F).
When the engine coolant temperature (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.
