Toyota Tacoma 2015-2018 Service Manual: Downhill Assist Control Switch Malfunction (Test Mode DTC) (C1379)

Toyota Tacoma 2015-2018 Service Manual / Brake Control / Dynamic Control Systems / Vehicle Stability Control System(for Hydraulic Brake Booster) / Downhill Assist Control Switch Malfunction (Test Mode DTC) (C1379)

DESCRIPTION

DTC C1379 is cleared when the crawl control switch sends a crawl control operation signal or when test mode ends.

DTC Code	DTC Detection Condition	Trouble Area
C1379	Stored only during test mode.	Crawl control switch (drive monitor switch) Harness or connector Skid control ECU (master cylinder solenoid)

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

When replacing the skid control ECU (master cylinder solenoid), perform calibration (See page ).
Inspect the fuses for circuits related to this system before performing the following inspection procedure.

PROCEDURE

1.	READ VALUE USING TECHSTREAM (CRAWL CONTROL SWITCH)

(a) Turn the ignition switch off.

(b) Connect the Techstream to the DLC3.

(d) Turn the Techstream on.

(e) Enter the following menus: Chassis / ABS/VSC/TRAC / Data List.

(f) Check the Data List for proper functioning of the crawl control switch.

ABS/VSC/TRAC

Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
Crawl Control Switch	Crawl speed selector switch status/ LOW, MIDLOW, MID, MIDHIGH or HIGH	Actual crawl speed selector switch position	-

OK:

The Techstream displays according to crawl control switch operation.

GO TO STEP 3

2.	CHECK TEST MODE DTC

(a) Perform the crawl control switch check in the Test Mode Procedure (See page OK: OK: ).

OK:

Test mode DTC C1379 is cleared.

USE SIMULATION METHOD TO CHECK

REPLACE MASTER CYLINDER SOLENOID

3.	INSPECT DRIVE MONITOR SWITCH

(a) Remove the crawl control switch (drive monitor switch) (See page (b) Inspect the crawl control switch (drive monitor switch) (See page ).

(b) Inspect the crawl control switch (drive monitor switch) (See page ).

REPLACE DRIVE MONITOR SWITCH

4.	INSPECT ROOF CONSOLE BOX ASSEMBLY

(a) Remove the roof console box assembly.

for Double Cab: (See page )
for Access Cab: (See page )

Text in Illustration

Component without harness connected

(Roof Console Box Assembly)

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
R44-1 (SWI3) - 2	Always	Below 1 Ω
R44-3 (DN) - 7	Always	Below 1 Ω
R44-4 (ECU) - 6	Always	Below 1 Ω
R44-5 (UP) - 3	Always	Below 1 Ω
R44-12 (GND) - 5	Always	Below 1 Ω

Result

Result	Proceed to
OK	A
NG (for Double Cab)	B
NG (for Access Cab)	C

REPAIR OR REPLACE HARNESS OR CONNECTOR (MASTER CYLINDER SOLENOID - ROOF CONSOLE BOX ASSEMBLY)

REPLACE ROOF CONSOLE BOX ASSEMBLY

Diameter of the Tire is not Uniform (C1337)

DESCRIPTION The skid control ECU (master cylinder solenoid) measures the speed of each wheel by receiving signals from the speed sensors. These signals are used for recognizing whether all 4 whee ...

Acceleration Sensor Power Supply Voltage Malfunction (C1381)

DESCRIPTION The skid control ECU (master cylinder solenoid) receives signals from the yaw rate and acceleration (airbag sensor assembly) via the CAN communication system. The airbag sensor assembl ...

Other materials:

Brake Warning Light does not Come ON
DESCRIPTION Refer to Brake Warning Light Remains ON (See page ). WIRING DIAGRAM Refer to Brake Warning Light Remains ON (See page ). CAUTION / NOTICE / HINT NOTICE: When replacing the skid control ECU (master cylinder solenoid), perform calibration (See page ). Inspect ...

Pressure Control Solenoid "G" Actuator Stuck Off (P28077F)
SYSTEM DESCRIPTION The ECM uses the vehicle speed signal and signals from the transmission revolution sensors (NT, SP2) to detect the actual gear (1st, 2nd, 3rd, 4th, 5th or 6th gear). The ECM compares the actual gear with the shift schedule in the ECM memory to detect mechanical problems of t ...

Disassembly
DISASSEMBLY PROCEDURE 1. INSPECT FRONT PROPELLER SHAFT UNIVERSAL JOINT SPIDER BEARING (a) Check the spider bearings for wear and damage. (b) Check each spider bearing's axial play by turning the yoke while holding the shaft tightly. Maximum bearing axial play: 0 to 0.05 mm (0 to 0.002 i ...