DTC C1791: Adaptive Variable Suspension(AVS) Switch Circuit [08/2019 - 08/2021]: Procedure

1. Turn the engine switch off.
2. Connect the Techstream to the DLC3.
3. Turn the engine switch on (IG).
4. Turn the Techstream on.
5. Enter the following menus: Chassis / Air suspension / Data List.
   AIR SUSPENSION
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   Damping Control Switch	Absorber control switch / NORMAL, COMFORT or SPORT	Indicates current absorber control switch position	-

6. Check that the value displayed on the Techstream changes by operating the absorber control switch (combination switch assembly) between COMF, NORMAL and SPORT.

   OK

   Absorber control switch (combination switch assembly) value changes.

   Result

   Result
   OK
   NG

Result: 

OK 

USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [08/2019 - 08/2020]  , or refer to  HOW TO PROCEED WITH TROUBLESHOOTING [08/2020 - 08/2021] 

Result: 

NG 

See step  2

1. Turn the engine switch off.
2. Remove the absorber control switch (combination switch assembly).

   Refer to REMOVAL [08/2015 - 08/2021]

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

   Standard Resistance

   Tester Connection	Switch Condition	Specified Condition
   9 (E) - 11 (ECU2)	COMF position	Below 1 Ω
   	Normal position	10 kΩ or higher
   9 (E) - 1 (ECU1)	SPORT position	Below 1 Ω
   	Normal position	10 kΩ or higher

   Result

   Result
   OK
   NG

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Component without harness connected (Absorber Control Switch [Combination Switch Assembly])

Result: 

NG 

REPLACE ABSORBER CONTROL SWITCH (COMBINATION SWITCH ASSEMBLY). Refer to  REMOVAL [08/2015 - 08/2021] 

Result: 

OK 

See step  3

1. Disconnect the i5 absorber control switch (combination switch assembly) connector.
2. Disconnect the A40 suspension control ECU connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   i5-1 (ECU1) - A40-23 (TSW1)	Always	Below 1 Ω
   i5-11 (ECU2) - A40-22 (TSW2)	Always	Below 1 Ω
   i5-9 (E) - Body ground	Always	Below 1 Ω
   i5-1 (ECU1) - Body ground	Always	10 kΩ or higher
   i5-11 (ECU2) - Body ground	Always	10 kΩ or higher

   Result

   Result
   OK
   NG

Result: 

OK 

REPLACE SUSPENSION CONTROL ECU. Refer to  REMOVAL [08/2015 - ] 

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR