Inspection Procedure

1. Check if the CAN communication system DTC is output (see DIAGNOSIS SYSTEM )

   Result 

   DTC RESULT DESCRIPTION
   
   

   Result	Proceed to
   DTC is not output	A
   DTC is output	B

B: REPAIR CAN COMMUNICATION SYSTEM 

A: Go to next step. 

1. Check the Data List for proper functioning of the downhill assist control switch.

   ABS/VSC/TRAC: 

   MEASUREMENT ITEM/RANGE AND DIAGNOSTIC NOTE
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   Downhill Assist Control Switch	Downhill assist control switch / ON or OFF	ON: Downhill assist control switch is ON OFF: Downhill assist control switch is OFF	-

   OK: ON (downhill assist control switch is ON) appears on the screen. 

NG: Go to step   5

OK: Go to next step. 

1. Select the Active Test, generate a control command, and then check that the downhill assist control indicator light operates.

   ABS/VSC/TRAC: 

   CONTROL RANGE AND DIAGNOSTIC NOTE
   
   

   Tester Display	Test Part	Control Range	Diagnostic Note
   Downhill Assist Control Light	Downhill assist control indicator light	Indicator light ON / OFF	Observe combination meter

   OK: The downhill assist control indicator light turns ON and OFF. 

OK: REPLACE ABS AND TRACTION ACTUATOR ASSEMBLY 

NG: Go to next step. 

1. Inspect the combination meter (see HOW TO PROCEED WITH TROUBLESHOOTING ).

NG: REPLACE COMBINATION METER ASSEMBLY 

OK: REPLACE ABS AND TRACTION ACTUATOR ASSEMBLY 

1. Remove the downhill assist control switch.
Fig 1: Identifying Downhill Assist Control Switch
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance of the switch.

   Standard resistance 

   TESTER CONNECTION AND SPECIFIED CONDITION
   
   

   Tester Connection	Switch Condition	Specified Condition
   4 - 1	Switch is pushed	Below 1 Ω
   4 - 1	Switch is not pushed	10 kΩ or higher

NG: REPLACE DOWNHILL ASSIST CONTROL SWITCH 

OK: Go to next step. 

1. Disconnect the A19 ECU connector.
Fig 2: Identifying A19 ECU And E31 Switch Connector Terminals
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Disconnect the E31 switch connector.
3. Measure the resistance of the wire harness side connectors.

   Standard resistance 

   TESTER CONNECTION AND SPECIFIED CONDITION
   
   

   Tester Connection	Specified Condition
   A19-28 (HDCS) - E31-4	Below 1 Ω
   E31-1 - Body ground	Below 1 Ω
   A19-28 (HDCS) - Body ground	10 kΩ or higher

NG: REPAIR OR REPLACE HARNESS AND CONNECTOR 

OK: REPLACE ABS AND TRACTION ACTUATOR ASSEMBLY