Tech Tip

June 10, 2013

T-TT-0058-10

RECOMMENDATIONS

Basic S)lstem 012eration

•
..

4WD ECU powers the
transfer case actuator
motor while monitoring
the limit switches

Selector switch
is moved from
2WDto4HI
Free

The system
operates in the
same order going
back to 2WD

The 4WD light(s)
turn on solid

•
•

Transfer case
differential is
engaged into
4Hi Lock

4WD EC U confirms
all input values are
correct for the
requested action

• ..
•

Front differential
engaged into
4WD

Transfer case
differential is
disengaged into
4Hi Free

Note: If the system does not complete the requested action or the actuator limit switches do not match the 4WD ECU
desired position, the 4WD light(s) will flash indicating a problem. Additionally if the system is unsure of its position, it may
stop operating and not move in or out of its current position.
Before Beginning Diagnosis:
• If the 4WD system is inoperative or has harsh engagement/disengagement while driving but works normally when
the wheels are off the ground, it may be caused by a difference in front and rear driveshaft speeds.
Confirm: Tire size differences, uneven wear, or incorrect inflation pressures.
• The vehicle must be stopped and transmission in N or the system will not go into 4LO and beeping will be heard.
• Confirm customer is not attempting to engage 4WD at speeds above 62MPH as operation will be prohibited .
• If the vehicle has a OTC in another system, diagnose that condition first as it may be prohibiting 4WD operation.
lns12ection Procedure
1. Print and complete the 4WD System Diagnosis Pre-Call W orksheet on TIS (refer to link on bottom of page 2).
2. Refer to the table on page 2. The columns in the table provide the correct voltage values for each component
position. Using the information from the Pre-Call worksheet, compare the voltages in the columns that match the
mechanical position and selector switch input of the system.
3. Identify which switch position(s) do not match the mechanical position of the system .
4. Inspect the component and circuit that is not completing the requested action. Example: Transfer case engaged in
4HI, transfer switch voltages correct for 4HI, ADD voltages not correct for 4HI , inspect ADD and related circuits.
Diagnostic Ti12s:
• If the 4WD light(s) flash in 2WD, make sure the front differential is not staying engaged in 4WD. Rotate the front
wheels by hand and if the front driveshaft turns, the front differential is engaged .
• Rotate the rear driveshaft by hand and note which direction the front driveshaft turns . If it turns in the same direction,
the center differential is engaged. If it turns in the opposite direction, the center differential is disengaged.
Tech Tip
V t.T.

l.0 2/9/20IO T

11/10/2013

Rev4

© 201 1, Toyota Motor Sales.USA

Page 1of2

@TOYOTA

Tech Tip

June 10, 2013

T-TT-0058-10

Sub1cct

Markel

4WD System Diagnosis

usA

Applicability

2008 - 2013 Sequoia
RECOMMENDATIONS

Circuit
HL 1
HL2
HL3*
TL 1
TL2
TL3
DL1
DL2
2-4
DL*
LO
4WD
ADD
NP*
L4

Pin #
1
2
3
6
7
8
10
11

2WD
0-1V
10-14V
10-14V
0-1V
10-14V
10-14V
10-14V
0-1V
o-1v

12

10-14V

10-14V

10-14V

10-14V

10-14V

13
14
15
16
21

10-14V
10-14V
10-14V
10-14V
10-14V

0.5V-0.7V
10-14V
0-1V
10-14V
10-14V

0.5V-0.7V
0-1V
0-1V
10-14V
10-14V

0-1V
10-14V
0-1V
10-14V
0-1V

0-1V
0-1V
0-1V
10-14V
o-1v

9

4HI
o-1v
10-14V
10-14V
10-14V
0-1V
10-14V
0-1V
10-14V
0.5V-0.7V

4HI lock
0-1V
10-14V
10-14V
10-14V
10-14V
0-1V
0-1V
10-14V
0.5V-0.7V

4LO
10-14V
o-1v
10-14V
10-14V
0-1V
10-14V
0-1V
10-14V
10-14V

4LO lock
10-14V
0-1V
10-14V
10-14V
10-14V
0-1V
0-1V
10-14V
10-14V

Circuit Function
Transfer case actuator HI/LO range
limit switches
Transfer case actuator 2WD/4WD &
Lock/Free lim it switches
ADD actuator limit switches

ut

*Operation Notes:
• HL3 voltage will drop to less than 1V during High - Low transition.
• DL is a momentary type input switch and will read Ov only when the center
differential request switch is depressed.
• NP will read Ov only when the transfer case is in a neutral position.

2\VO

I-

OI+

n .•

ON

- - - - -

I - --

.

Frcl'

l .u c.: k

-I_______

-+-_

ll it;h

.

, . - - -- -- -Ill.I

TI'~:: __ ) _________ 1---r --~-------------- \

u; ·:::

___ __

Ill~

(:: - - - - - - - - - - -

r·
N

. __ .
IAM

-1 --- ---- -- ----

I-----------

IJI I·

DISENGAGED

DL1 &

ON

AOO

------]

ENGAGED

t

O il

ON--- - ---- --- --'-· ----

llL'

·~:

_____ _

1-------- ---1 ____ __

DL2

: ~. --------------~I__

-------1...1.------------U..------------------------""'--.J

LINK REFERENCES

1. 4WD System Diagnosis Pre-Call Worksheet
2. Foreword (2008 Sequoia)
3. JF3A TRANSFER I 4WD I AWD: TOUCH SELECT 2-4 AND HIGH-LOW SYSTEM : PARTS
LOCATION (2011 Sequoia)
4. JF3A TRANSFER I 4WD I AWD: TOUCH SELECT 2-4 AND HIGH-LOW SYSTEM: FAIL-SAF E
CHART 2011 Se uoia
Tech Tip

11/10/2013

Rev4

© 2011, Toyota Motor Sales .USA

Page 2 of 2