DTC C1422: Master Cylinder Pressure Sensor Zero Point High Malfunction: Procedure

1. Check that the stop lights come on when the brake pedal is depressed, and go off when the brake pedal is released.

   OK

   Condition	Illumination Condition
   Brake pedal depressed	ON
   Brake pedal released	OFF

NG → See step   8 

OK: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the engine switch on (IG).
3. Select the Data List on the Techstream. Refer to DATA LIST / ACTIVE TEST .
   DATA LIST
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   Stop Light SW	Stop light switch / ON or OFF	ON: Brake pedal depressed OFF: Brake pedal released	-

4. Check that the stop light condition observed on the Techstream changes according to brake pedal operation.

   OK

   The Techstream displays ON or OFF according to brake pedal operation.

NG → See step   5 

OK: Go to next step 

1. Turn the engine switch off.
2. Check the brake pedal height and stop light switch installation. Refer to ADJUSTMENT .

   OK

   The brake pedal height and stop light switch installation are normal.

NG → See step   9 

OK: Go to next step 

1. Clear the DTCs. Refer to DTC CHECK / CLEAR .
2. Start the engine.
3. Drive the vehicle at a speed of 40 km/h (25 mph) or more and perform braking test (decelerate the vehicle by depressing the brake pedal).
4. Check if the same DTC is recorded. Refer to DTC CHECK / CLEAR .

   Result

   Result	Proceed to
   DTC (C1422) is not output	A
   DTC (C1422) is output	B

B → See step   7 

A → See step   6 

1. Turn the engine switch off.
   Fig 1: Identifying Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Make sure that there is no looseness at the locking part and the connecting part of the connectors.
3. Disconnect the skid control ECU connector.
4. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Switch Condition	Specified Condition
   A58-2 (STP1) - Body ground	Stop light switch ON (Brake pedal depressed)	8 to 14 V
   A58-2 (STP1) - Body ground	Stop light switch OFF (Brake pedal released)	Below 1.5 V

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (STP1 CIRCUIT) 

OK → See step   7