For 1990-2009 cars

# Info - 1-2, 2-3, 3-4, 4-5 Shift and Torque Converter Clutch (TCC) Characteristics During Cold Weather Operation on 4L60-E, 4L80-E or Allison Transmissions

Subject: | 1-2, 2-3, 3-4, 4-5 Shift and Torque Converter Clutch (TCC) Characteristics During Cold Weather Operation on 4L60-E, 4L80-E or Allison Transmissions

Models: | 2002-2004 Cadillac Escalade, Escalade EXT

| 2003-2004 Cadillac ESV

| 2001-2004 Chevrolet and GMC Light Duty Full-Size Pickup and Utility Models

| 2003-2004 HUMMER H2

| with 4.3L, 4.8L, 5.3L, 6.0L or 8.1L Gas Engine (VINs W, V, T, N, U, G -- RPOs L35, LR4, LM7, LQ9, LQ4, L18) or 6.6L Diesel Engine (VINs 1, 2 -- RPOs LB7, LLY)

| and 4L60-E, 4L80-E or Allison Automatic Transmission (RPO M74-Transmission Auto 5-Speed, Allison, LCT 1000, 3.10 1st, 1.00 4th, 0.71 5th, O/D, Conversion Clutch)

This bulletin is being revised to add model years, model and Allison transmission information. Please discard Corporate Bulletin Number 01-07-30-031 (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 the intake air temperature (IAT) is less than -7°C (19°F), 1-2, 2-3 and 3-4 upshift speeds will be affected as detailed below.

### Vehicles Equipped with Allison Transmissions

#### Range Shifts with M74 and L18

No heater performance utilized for range shifts for all model years.

#### (2001-2004 Model Year) TCC Operation with M74 and L18

If the transmission fluid temperature is less than 18°C (64.4°F), torque converter clutch (TCC) operation will not occur until the transmission fluid temperature is greater than 22°C (71.6°F).

#### (2001-2004 Model Year) 1-2 Shift with M74 and LB7 or LLY

No heater performance for 1-2 range shift for all model years.

#### (2001-2004 Model Year) 2-3 Shift with M74 and LB7

If the throttle position (TP) is less than 43 percent, the 2-3 upshift will take place at a minimum speed of 35 km/h (22 mph). This raises the shift point a maximum of 2 mph. If the TP is above 43 percent, the shifts will follow the normal shift pattern. When the transmission sump temperature reaches 44°C (111.2°F), 2-3 upshifts will follow the normal shift pattern.

#### (2004 Model Year) 2-3 Shift with M74 and LLY

If the throttle position (TP) is less than 37 percent, the 2-3 upshift will take place at a minimum speed of 33 km/h (20 mph). This raises the shift point a maximum of 2 mph. If the TP is above 37 percent, the shifts will follow the normal shift pattern. When the engine coolant temperature reaches 68°C (154.4°F), 2-3 upshifts will follow the normal shift pattern.

#### (2001-2004 Model Year) 3-4 Shift with M74 and LB7

If the throttle position (TP) is less than 56 percent, the 3-4 upshift will take place at a minimum speed of 52 km/h (32 mph). This raises the shift point a maximum of 5 mph. If the TP is above 56 percent, the shifts will follow the normal shift pattern. When the transmission sump temperature reaches 44°C (111.2°F), 3-4 upshifts will follow the normal shift pattern.

#### (2004 Model Year) 3-4 Shift with M74 and LLY

If the throttle position (TP) is less than 37 percent, the 3-4 upshift will take place at a minimum speed of 50 km/h (31 mph). This raises the shift point a maximum of 6 mph. If the TP is above 37 percent, the shifts will follow the normal shift pattern. When the engine coolant temperature reaches 68°C (154.4°F), 3-4 upshifts will follow the normal shift pattern.

#### (2001-2004 Model Year) 4-5 Shift with M74 and LB7

If the throttle position (TP) is less than 56 percent, the 4-5 upshift will take place at a minimum speed of 70 km/h (44 mph). This raises the shift point a maximum of 6 mph. If the TP is above 56 percent, the shifts will follow the normal shift pattern. When the transmission sump temperature reaches 44°C (111.2°F), 4-5 upshifts will follow the normal shift pattern.

#### (2004 Model Year) 4-5 Shift with M74 and LLY

If the throttle position (TP) is less than 56 percent, the 4-5 upshift will take place at a minimum speed of 67 km/h (42 mph). This raises the shift point a maximum of 6 mph. If the TP is above 56 percent, the shifts will follow the normal shift pattern. When the engine coolant temperature reaches 68°C (154.4°F), 4-5 upshifts will follow the normal shift pattern.

#### (2001-2004 Model Year) TCC Operation with M74 and LB7 or LLY

If the transmission fluid temperature is less than 29°C (84.2°F), torque converter clutch (TCC) operation will not occur until the transmission fluid temperature is greater than 31°C (87.8°F).

### Vehicles Equipped with 4L60-E or 4L80-E Transmissions

#### 1-2 Upshift

If the throttle position (TP) is less than 37 percent, the 1-2 upshift will take place at a minimum speed of 19 km/h (12 mph).

#### 2-3 Upshift

• | (2001 Model Year) 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).

• | (2002-2004 Model Year) If the throttle position (TP) is less than 37 percent, the 2-3 upshift will take place at a minimum speed of 43 km/h (27 mph).

• | If the throttle position (TP) is above 37 percent, the shifts will follow the normal shift pattern.

#### 3-4 Upshift

• | (2001 Model Year) 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).

• | (2002-2004 Model Year) If the throttle position (TP) is less than 37 percent, the 3-4 upshift will take place at a minimum speed of 64 km/h (40 mph).

• | If the throttle position (TP) is above 37 percent, the shifts will follow 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).

(2001 Model Year) When the engine coolant temperature (ECT) reaches 77°C (171°F), 2-3 and 3-4 upshifts will follow the normal shift patterns. A brief description of operation may also be included in the Owner's Manual.

(2002 Model Year) When the ECT reaches 80°C (176°F), 2-3 and 3-4 upshifts will follow the normal shift patterns. A brief description of operation may also be included in the Owner's Manual.