Toyota Tacoma (2015-2018) Service Manual: Automatic Disconnecting Differential Motor Limit Switch Circuit (P17A4)

Toyota Tacoma (2015-2018) Service Manual / Vf2cm Transfer / Touch Select 2-4 And High-low System / Automatic Disconnecting Differential Motor Limit Switch Circuit (P17A4)

DESCRIPTION

When the A.D.D. actuator switches between 2WD and 4WD, the DL1 and DL2 terminals of the limit switch and ADD terminal of the A.D.D. position switch change to one of the following ON/OFF combinations listed in the table below.

Terminal	In 2WD	Switching between 2WD and 4WD		In 4WD
DL1	ON (GND)	ON (GND)		OFF (OPEN)
DL2	OFF (OPEN)	ON (GND)		ON (GND)
ADD	OFF (OPEN)	OFF (OPEN)	ON (GND)	ON (GND)

A malfunction is detected depending on the combination of the 3 circuits that make up the limit switch and A.D.D. position switch.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
P17A4	Automatic Disconnecting Differential Motor Limit Switch Circuit	Diagnosis Condition: Directly after the ignition switch is turned to ON, or while switching between 2WD and H4 (A.D.D. shift motor operating) with the ignition switch turned to ON Malfunction Status: The ON/OFF combination of DL1, DL2 and ADD does not match the pattern Malfunction Time: 0 seconds Other: 1 trip detection logic	Wire harness and connector 4 wheel drive control ECU A.D.D. actuator (differential vacuum actuator assembly)

WIRING DIAGRAM

PROCEDURE

1.	CHECK HARNESS AND CONNECTOR (4 WHEEL DRIVE CONTROL ECU - DIFFERENTIAL VACUUM ACTUATOR ASSEMBLY)

(a) Disconnect the F13 4 wheel drive control ECU connector.

(b) Disconnect the A3 A.D.D. actuator (differential vacuum actuator assembly) connector.

Disconnect the S1 skid control ECU (Master Cylinder Solenoid) connector.

for Vacuum Brake Booster:

Disconnect the S1 skid control ECU (brake actuator assembly) connector.

(d) for 2GR-FKS:

Disconnect the E13 ECM connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
F13-8 (DL1) - A3-6 (DL1)	Always	Below 1 Ω
F13-7 (DL2) - A3-5 (DL2)	Always	Below 1 Ω
F13-2 (ADD) - A3-3 (ADD)	Always	Below 1 Ω
A3-4 (GND) - Body ground	Always	Below 1 Ω
F13-8 (DL1) or A3-6 (DL1) - Body ground	Always	10 kΩ or higher
F13-7 (DL2) or A3-5 (DL2) - Body ground	Always	10 kΩ or higher
F13-2 (ADD) or A3-3 (ADD) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

2.	INSPECT DIFFERENTIAL VACUUM ACTUATOR ASSEMBLY (LIMIT SWITCH AND A.D.D. POSITION SWITCH)

(a) Disconnect the A.D.D. actuator (differential vacuum actuator assembly) connector.

(b) for Hydraulic Brake Booster:

Disconnect the S1 skid control ECU (Master Cylinder Solenoid) connector.

for Vacuum Brake Booster:

Disconnect the S1 skid control ECU (brake actuator assembly) connector.

Disconnect the E13 ECM connector.

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

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
A3-6 (DL1) - Body ground	Ignition switch ON	10 to 14 V
A3-5 (DL2) - Body ground	Ignition switch ON	10 to 14 V
A3-3 (ADD) - Body ground	Ignition switch ON	10 to 14 V

Text in Illustration

*a	Front view of wire harness connector (to A.D.D. Actuator (Differential Vacuum Actuator Assembly))

REPLACE DIFFERENTIAL VACUUM ACTUATOR ASSEMBLY

REPLACE 4 WHEEL DRIVE CONTROL ECU

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Parts Location
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