DTC C1A05: Stop Light Switch Circuit; DTC C1A4B: Stop Light Relay Circuit: 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   14 

OK: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Enter the following menus: Powertrain / Radar Cruise / Data List.
5. Check the Data List for proper functioning of the stop light switch.
   RADAR CRUISE
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   Stop Light SW 1 (M CPU)	Stop light switch (Main-CPU) signal / ON or OFF	ON: Brake pedal depressed OFF: Brake pedal released	-
   Stop Light SW 1 (S CPU)	Stop light switch (Sub-CPU) signal / ON or OFF	ON: Brake pedal depressed OFF: Brake pedal released	-
   Stop Light SW 2 (M CPU)	Stop light switch (Main-CPU) signal / ON or OFF	ON: Brake pedal depressed OFF: Brake pedal released	-

   OK

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

NG → See step   10 

OK: Go to next step 

1. Disconnect the stop light switch assembly connector.
2. Disconnect the brake booster with master cylinder assembly (skid control ECU) connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance (Check for Open)

   Tester Connection	Condition	Specified Condition
   A88-2 (L) - A58-33 (STP)	Always	Below 1 Ω

   Standard Resistance (Check for Short)

   Tester Connection	Condition	Specified Condition
   A88-2 (L) or A58-33 (STP) - Body ground	Always	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - SKID CONTROL ECU) 

OK: Go to next step 

1. Disconnect the stop light control relay connector.
2. Measure the resistance according to the value(s) in the table below.

   Standard Resistance (Check for Open)

   Tester Connection	Condition	Specified Condition
   A28-1 (OUT) - A58-6 (STP2)	Always	Below 1 Ω
   A28-5 (STP) - A58-33 (STP)	Always	Below 1 Ω
   A28-9 (ACC) - A58-3 (STP0)	Always	Below 1 Ω

   Standard Resistance (Check for Short)

   Tester Connection	Condition	Specified Condition
   A28-1 (OUT) or A58-6 (STP2) - Body ground	Always	10 kΩ or higher
   A28-5 (STP) or A58-33 (STP) - Body ground	Always	10 kΩ or higher
   A28-9 (ACC) or A58-3 (STP0) - Body ground	Always	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT CONTROL RELAY - SKID CONTROL ECU) 

OK: Go to next step 

1. Inspect the stop light control relay. Refer to INSPECTION .

NG → See step   15 

OK: Go to next step 

1. Replace the brake booster with master cylinder assembly (skid control ECU). Refer to REMOVAL .

NEXT: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Clear the DTCs. Refer to DTC CHECK / CLEAR .
4. Perform the following to make sure that the DTC detection conditions are met.

   HINT: 

   If the detection conditions are not met, the malfunction cannot be detected.

   1. Drive the vehicle at a speed for which radar cruise control operation is possible.
   2. Turn the cruise control system on using the cruise control switch (ON-OFF button).
   3. Push the cruise control switch to -/SET to begin control of vehicle speed using the cruise control system.
5. Enter the following menus: Powertrain / Radar Cruise / Trouble Codes.
6. Check for DTCs.

   Result

   Result	Proceed to
   DTC is not output	A
   DTC C1A05 or C1A4B is output	B

B → See step   8 

A → END 

1. Replace the power management control ECU. Refer to REMOVAL .

NEXT: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Clear the DTCs. Refer to DTC CHECK / CLEAR .
4. Perform the following to make sure that the DTC detection conditions are met.

   HINT: 

   If the detection conditions are not met, the malfunction cannot be detected.

   1. Drive the vehicle at a speed for which radar cruise control operation is possible.
   2. Turn the cruise control system on using the cruise control switch (ON-OFF button).
   3. Push the cruise control switch to -/SET to begin control of vehicle speed using the cruise control system.
5. Enter the following menus: Powertrain / Radar Cruise / Trouble Codes.
6. Check for DTCs.

   Result

   Result	Proceed to
   DTC is not output	A
   DTC C1A05 or C1A4B is output	B

B → See step   16 

A → END 

1. Disconnect the stop light switch assembly connector.
   Fig 1: Checking A88 Connector Terminals

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

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   A88-1 (B) - A88-3 (GND)	Power switch off	11 to 14 V
   A88-5 (B) - A88-3 (GND)	Power switch ON	11 to 14 V

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A88-3 (GND) - Body ground	Always	Below 1 Ω

   TEXT IN ILLUSTRATION
   
   

   *a	Front view of wire harness connector (to Stop Light Switch Assembly)

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH - IG2 RELAY) 

OK: Go to next step 

1. Remove the stop light switch assembly. Refer to REMOVAL .
   Fig 2: Checking A88 Connector Terminals

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

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   A88-2 (L) - A88-3 (GND)	Power switch off, Brake pedal not depressed	Below 1 V
   A88-2 (L) - A88-3 (GND)	Power switch off, Brake pedal depressed	11 to 14 V
   A88-4 (L) - A88-3 (GND)	Power switch ON, Brake pedal not depressed	11 to 14 V
   A88-4 (L) - A88-3 (GND)	Power switch ON, Brake pedal depressed	Below 1 V

   TEXT IN ILLUSTRATION
   
   

   *a	Component with harness connected (Stop Light Switch Assembly)

NG → See step   17 

OK: Go to next step 

1. Disconnect the driving support ECU assembly connector.
2. Measure the resistance according to the value(s) in the table below.

   Standard Resistance (Check for Open)

   Tester Connection	Condition	Specified Condition
   L151-27 (STP-) - A88-2 (L)	Always	Below 1 Ω
   L151-28 (ST1-) - A88-4 (L)	Always	Below 1 Ω

   Standard Resistance (Check for Open)

   Tester Connection	Condition	Specified Condition
   L151-27 (STP-) or A88-2 (L) - Body ground	Always	10 kΩ or higher
   L151-28 (ST1-) or A88-4 (L) - Body ground	Always	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (DRIVING SUPPORT ECU ASSEMBLY - STOP LIGHT SWITCH ASSEMBLY) 

OK: Go to next step 

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

   Standard Resistance (Check for Short)

   Tester Connection	Condition	Specified Condition
   A88-2 (L) - Body ground	Always	10 kΩ or higher
   A88-4 (L) - Body ground	Always	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - BODY GROUND) 

OK → See step   18