DTC

C0023:62, C0040:64, C0040:86

Brake light/Brake switch

DETECTION CONDITION

• C0023:62

• Brake light ON signal is not input even though the brake light request signal is input.

• Brake light ON signal is input even though the brake light request signal is not input.

• Brake light ON signal is not input when the brake fluid pressure sensor signal reaches the specified value.

• Communication error with brake light is detected in CAN communication via RBCM.

• C0040:64

• Brake switch ON signal is input for 15 min or more when driving at a vehicle speed of 15 km/h {9.3 mph} or more.

• C0040:86

• Communication error with brake switch is detected in CAN communication via PCM.

FAIL-SAFE FUNCTION

• C0023:62

• Illuminates the master warning light*¹.

• Inhibits the Mazda Radar Cruise Control (MRCC), and Smart City Brake Support (SCBS) controls.

• C0040:64, C0040:86

• Illuminates the ABS warning light, TCS/DSC indicator light, and master warning light*¹.

• Tire pressure monitoring system warning light illuminates after flashes.

• Inhibits the ABS, brake assist, TCS, Hill Launch Assist (HLA), vehicle roll prevention function*², DSC, Mazda Radar Cruise Control (MRCC)*², Smart City Brake Support (SCBS)*², and TPMS controls.

*¹: Vehicles with Smart City Brake Support (SCBS).

*²: If equipped.

POSSIBLE CAUSE

• Open in wiring harness between the DSC HU/CM terminal AF and the ignition switch.

• Brake switch malfunction

• Poor connection at connectors (female terminal)

• Rear Body Control Module (RBCM) malfunction

• PCM malfunction

STEP

INSPECTION

ACTION

1

• Switch the ignition ON (engine off).

• Measure the voltage at the DSC HU/CM connector terminal AF (vehicle harness side) and body ground.

• Is the voltage B+?

Yes

Go to the next step.

No

Refer to the wiring diagram and verify whether or not there is a common connector between ignition switch and DSC HU/CM terminal AF (vehicle harness side).

If there is a common connector:

• Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for an open circuit.

• Repair or replace the malfunctioning part.

If there is no common connector:

• Repair or replace the wiring harness which has an open circuit.

Go to Step 8.

2

• Switch the ignition ON (engine off).

• Measure the voltage between the PCM connector terminal 2G (vehicle harness-side) and body ground when the brake pedal is depressed and released.

• Voltage

  Brake pedal depressed: B+

  Brake pedal released: 1 V or less

• Is the voltage normal?

Yes

Go to the Step 8.

No

If it is B+ under any condition, then go to the next step.

If it is 1 V or less under any condition, then go to Step 4.

3

• Disconnect the brake switch connector.

• Measure voltage between the brake switch connector terminal D (vehicle harness-side) and body ground.

• Is the voltage 1 V or less?

Yes

Go to Step 5.

No

Refer to the wiring diagram and verify whether or not there is a common connector between PCM connector terminal 2G (vehicle harness-side) and brake switch connector terminal D (vehicle harness side).

If there is a common connector:

• Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for a short to power supply.

• Repair or replace the malfunctioning part.

If there is no common connector:

• Repair or replace the wiring harness which has a short to power supply.

Go to Step 8.

4

• Disconnect the PCM connectors.

• Disconnect the brake switch connector.

• Inspect continuity between the PCM and brake switch as follows.

• SKYACTIV-G 2.5

• PCM connector terminal 2G (vehicle harness-side) and brake switch connector terminal D (vehicle harness-side)

• Is there continuity?

Yes

Go to the next step.

No

Refer to the wiring diagram and verify whether or not there is a common connector between PCM connector terminal 2G (vehicle harness-side) and brake switch connector terminal D (vehicle harness side).

If there is a common connector:

• Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for an open circuit.

• Repair or replace the malfunctioning part.

If there is no common connector:

• Repair or replace the wiring harness which has an open circuit.

Go to Step 8.

5

• Inspect the brake switch.

  (See BRAKE SWITCH INSPECTION.)

• Is the brake switch normal?

Yes

Go to the next step.

No

Replace the brake switch, then go to Step 8.

(See BRAKE PEDAL REMOVAL/INSTALLATION.)

6

• Reconnect all disconnected connectors.

• Using the M-MDS, perform the DTC inspection for the rear body control module (RBCM).

  (See DTC INSPECTION [REAR BODY CONTROL MODULE (RBCM)].)

• Are any DTCs detected?

Yes

Go to applicable DTC inspection.

(See DTC TABLE [REAR BODY CONTROL MODULE (RBCM)].)

No

Go to the next step.

7

• Using the M-MDS, perform the DTC inspection for the PCM.

  (See ON-BOARD DIAGNOSTIC TEST [SKYACTIV-G 2.5].)

• Are any DTCs detected?

Yes

Go to applicable DTC inspection.

(See DTC TABLE [SKYACTIV-G 2.5].)

No

Go to the next step.

8

• Reconnect all disconnected connectors.

• Clear the DTCs from the memory.

  (See ON-BOARD DIAGNOSIS [DYNAMIC STABILITY CONTROL (DSC)].)

• Start the engine and drive the vehicle at 20 km/h {12 mph} or more.

• Are the same DTCs present?

Yes

Repeat the inspection from Step 1.

No

Go to the next step.

9

• Are any other DTCs output?

Yes

Go to the applicable DTC inspection.

(See ON-BOARD DIAGNOSIS [DYNAMIC STABILITY CONTROL (DSC)].)

No

DTC troubleshooting completed.