Transfer Case - Not Shifting Temperatures Below Freezing

T-SB-0079-08

May 30, 2008

Transfer Case Not Shifting with Temperatures Below Freezing

Service Category
Drivetrain

Section
Transfer 4wd/Awd

Market
USA

Applicability

Introduction

Some customers may be concerned about the inability to shift the transfer case between 2WD 4WD High and 4WD Low after an overnight cold soak with temperatures below freezing. An improved transfer case actuator and revised 4WD computer logic has been implemented for this condition.

Use the following repair procedure to address customer concerns.

Warranty Information

^ This repair is covered under the Toyota Powertrain Warranty. This warranty is in effect for 60 months or 60,000 miles, whichever occurs first, from the vehicle's in-service date.

^ Warranty application is limited to correction of a problem based upon a customer's specific complaint.





Production Change Information

This TSB applies to vehicles produced BEFORE the Production Change Effective VINs shown.





Parts Information





Required Tools & Equipment

Repair Procedure

1. Confirm customer complaint of no shifting between 2WD 4WD High and 4WD Low gear positions after an overnight cold soak with temperatures below freezing (32°F/0°C)

^ If the vehicle is parked inside with temperatures above freezing, normal operation should be observed.

^ If the vehicle is driven for 5-10 minutes, normal operation may be observed because of transfer case gear oil temperature increasing above 32°F (0°C).

2. Remove the transfer case from the vehicle.

Refer to the Technical Information System (TIS) 2007 or 2008 model year Tundra Repair Manual:

2007 or 2008 Tundra: Drivetrain - Transfer/4wd/Awd - "JF1A Transfer: Transfer Assembly: Removal"

HINT
JF1A transfer case is used on both the 4.7 L and 5.7 L.





3. Remove the 4WD computer from the vehicle.

Refer to TIS 2007 or 2008 model year Tundra Repair Manual:

2007 or 2008 Tundra: Drivetrain - Transfer/4wd/Awd - "JF1A Transfer: 4WD Control ECU: Removal"

4. Install the NEW 4WD computer.

Refer to TIS 2007 or 2008 model year Tundra Repair Manual:

2007 or 2008 Tundra: Drivetrain - Transfer/4wd/Awd - "JF1A Transfer: 4WD Control ECU: Installation"

5. Disassemble the transfer case to replace the transfer case actuator assembly.

Refer to TIS 2007 or 2008 model year Tundra Repair Manual:

2007 or 2008 Tundra: Drivetrain - Transfer/4wd/Awd - "JF1A Transfer: Transfer Assembly: Disassembly"

NOTE
Complete steps 1 through the "Remove Transfer Shift Actuator Assembly" step. Do NOT complete any further steps.

6. Install the NEW transfer case actuator assembly into the transfer case.

Refer to TIS 2007 or 2008 model year Tundra Repair Manual:

2007 or 2008 Tundra: Drivetrain - Transfer/4wd/Awd - "JF1A Transfer: Transfer Assembly: Reassembly"

NOTE
Start at the "Install Transfer Shift Actuator Assembly" step and complete all remaining steps through the end of the Reassembly procedure.

7. Install the transfer case assembly into the vehicle.

Refer to TIS 2007 or 2008 model year Tundra Repair Manual:

2007 or 2008 Tundra: Drivetrain - Transfer/4wd/Awd - "JF1A Transfer: Transfer Assembly: Installation"

8. Test drive the vehicle and confirm proper operation of the 4WD system.