Toyota Tundra. Manual — part 2944

Fig. 135: Changing 4WD Control Switch From 2WD To 4H
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

If there is a malfunction, inspect the switch, ECU, transfer shift actuator and A.D.D. actuator.
If the system is normal, there may be a malfunction in the CAN communication system or
combination meter. In this case, first check the CAN communication system (See CAN
COMMUNICATION SYSTEM ). Then check the combination meter (See HOW TO
PROCEED WITH TROUBLESHOOTING ).

b. 4LO Indicator Light:

1. Turn the ignition switch ON.

2. Change the 4WD control switch from 2WD to 4H. Then change it from 4H to 4L after the

4HI indicator light illuminates (after 4H switch completion).

3. Check the 4LO indicator light.

OK

4LO INDICATOR LIGHT SPECIFIED CONDITION CHART

If there is a malfunction, inspect the switch, ECU and actuator. If the system is normal, the
combination meter may be malfunctioning.

2. INSPECT FUSE (4WD)

a. Remove the 4WD fuse from the main body ECU.

b. Measure the resistance according to the value(s) in the table below.

2WD to 4H

4HI indicator light comes on or 4HI indicator light comes on after it is
blinking

Switch Condition

Specified Condition

After 2WD to 4WD HIGH switch
completion, 4H to 4L

4LO indicator light comes on or 4LO indicator light
comes on after it is blinking

2009 Toyota Tundra

2009 TRANSMISSION JF1A Transfer - Tundra

Standard resistance

FUSE (4WD) TESTER CONNECTION AND SPECIFIED CONDITION

Fig. 136: Inspecting Fuse (4WD)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

If a fuse is blown, inspect the harness connected to the fuse for a short circuit, and repair or replace
the harness or replace the fuse.

3. INSPECT 4WD CONTROL ECU (POWER SUPPLY)

a. Measure the voltage according to the value(s) in the table below.

Standard voltage

4WD CONTROL ECU (POWER SUPPLY) TESTER CONNECTION AND SPECIFIED
CONDITION VOLTAGE

Tester Connection Condition Specified Condition

4WD fuse

Always

Below 1 ohms

Tester Connection

Switch Condition Specified Condition

A26-3 (IG) - Body ground Ignition switch ON

11 to 14 V

2009 Toyota Tundra

2009 TRANSMISSION JF1A Transfer - Tundra

Fig. 137: Inspecting 4WD Control ECU (Power Supply)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

If there is a malfunction, inspect the harness or connector. If the harness is malfunctioning, repair
or replace harness or connector. If the harness or connector is normal, replace the 4WD control
ECU (see REMOVAL ).

b. Measure the resistance according to the value(s) in the table below.

Standard resistance

4WD CONTROL ECU (POWER SUPPLY) TESTER CONNECTION AND SPECIFIED
CONDITION RESISTANCE

If there is a malfunction, repair or replace the harness or connector.

4. INSPECT 4WD CONTROL ECU (4WD CONTROL SWITCH)

a. Measure the voltage according to the value(s) in the table below.

Standard voltage

4WD CONTROL ECU (4WD CONTROL SWITCH) TESTER CONNECTION AND
SPECIFIED CONDITION VOLTAGE

Tester Connection

Condition Specified Condition

A26-4 (GND) - Body ground Always

Below 1 ohms

Tester Connection

Switch Condition

Specified

Condition

A25-11 (2-4) - Body

ground

Ignition switch ON 4WD control switch 2WD
position

Below 1.5 V

Ignition switch ON 4WD control switch 4H
position

Below 1.5 V

2009 Toyota Tundra

2009 TRANSMISSION JF1A Transfer - Tundra

Fig. 138: Inspecting 4WD Control ECU (4WD Control Switch)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

If there is a malfunction, check the power supply. If the power supply is normal, inspect the 4WD
control switch (see ON-VEHICLE INSPECTION ).

5. INSPECT 2WD-4WD TRANSFER SHIFT ACTUATOR

HINT:

After inspecting the power supply or 4WD control switch, inspect the 2WD-4WD transfer shift actuator.

a. Check the harness and connector (ECU - 2WD-4WD transfer shift actuator).

1. Disconnect the D67 actuator connector.

2. Disconnect the A25 and A26 ECU connectors.

3. Measure the resistance according to the value(s) in the table below.

Ignition switch ON 4WD control switch 4L
position

10.5 to 14 V

A25-13 (LO) - Body

ground

Ignition switch ON 4WD control switch 2WD
position

10.5 to 14 V

Ignition switch ON 4WD control switch 4H
position

Below 1.5 V

Ignition switch ON 4WD control switch 4L
position

Below 1.5 V

2009 Toyota Tundra

2009 TRANSMISSION JF1A Transfer - Tundra