DTC C1A05: Stop Light Switch Circuit: Procedure

1. Check the Data List for proper functioning of the stop light switch. Refer to DATA LIST / ACTIVE TEST .
   RADAR CRUISE
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   Stp Light SW1 (M CPU)	Stop light switch signal (Main CPU)/ON or OFF	ON: Brake pedal is depressed OFF: Brake pedal is released	-
   Stp Light SW1 (S CPU)	Stop light switch signal (Sub CPU)/ON or OFF	ON: Brake pedal is depressed OFF: Brake pedal is released	-

   OK

   Display changes according to brake pedal operation described in above table.

NG → See step   2 

OK → See step   5 

1. Remove the STOP fuse from the main body ECU.
2. Remove the ECU-IG fuse from the engine room No. 2 junction block.
3. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   STOP fuse	Always	Below 1 Ω
   ECU-IG fuse	Always	Below 1 Ω

NG → REPLACE FUSE 

OK: Go to next step 

1. Remove the stop light switch. Refer to REMOVAL .
   Fig 1: Identifying Stop Light Switch Pin

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Switch Condition	Specified Condition
   1 - 2	Not pushed	Below 1 Ω
   1 - 2	Pushed	10 kΩ or higher
   3 - 4	Pushed	Below 1 Ω
   3 - 4	Not pushed	10 kΩ or higher

NG → See step   6 

OK: Go to next step 

Fig 2: Identifying Driver Support ECU Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Disconnect the A33 ECU connector.
2. Measure the voltage according to the value(s) in the table below.

   Standard voltage

   Tester Connection	Switch Condition	Specified Condition
   A33-11 (STP-) - Body ground	Brake pedal is released	11 to 14 V
   A33-11 (STP-) - Body ground	Brake pedal is depressed	Below 1 V
   A33-34 (ST1-) - Body ground	Power switch is ON (IG), brake pedal is released	11 to 14 V
   A33-34 (ST1-) - Body ground	Power switch is ON (IG), brake pedal is depressed	Below 1 V

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK → See step   5