LEMON Manuals: Even more car manuals for everyone
Home >> Mazda >> 2017 >> CX-5 Grand Select, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 104 (On-Board Diagnostic - Rear Body Control Module (RBCM)) >> DTC C0023-14; Brake Light Circuit Malfunction >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2017 Mazda 3. However, it is still accessible from the selected car via links, so may be relevant.
DIAGNOSTIC PROCEDURE

Step Inspection Action
1 VERIFY REAR BODY CONTROL MODULE (FBCM) DTCs AGAIN Yes Brake light (bulb type)
  • Go to the next step.

    Brake light (LED type)

  • Go to Step 4.
No Go to Step 17.
2 INSPECT BRAKE LIGHT BULB (LH)
  • Inspect the brake light bulb (LH).
  • Is the brake light bulb (LH) normal?
 Yes Go to the next step.
No Replace the brake light bulb (LH), then go to Step 17.
(See BRAKE LIGHT/TAILLIGHT/REAR SIDE MARKER LIGHT BULB REMOVAL/INSTALLATION .)
3 INSPECT BRAKE LIGHT BULB (RH)
  • Inspect the brake light bulb (RH).
  • Is the brake light bulb (RH) normal?
 Yes Go to the next step.
No Replace the brake light bulb (RH), then go to Step 17.
(See BRAKE LIGHT/TAILLIGHT/REAR SIDE MARKER LIGHT BULB REMOVAL/INSTALLATION .)
4 INSPECT HIGH-MOUNT BRAKE LIGHT CONNECTOR CONDITION Yes Go to the next step.
No Repair or replace the connector, then go to Step 17.
5 INSPECT BRAKE LIGHT (LH) CONNECTOR CONDITION
  • Disconnect the brake light (LH) connector.
  • Inspect the connector engagement and connection condition and inspect the terminals for damage, deformation, corrosion, or disconnection.
  • Is the connector normal?
 Yes Go to the next step.
No Repair or replace the connector, then go to Step 17.
6 INSPECT BRAKE LIGHT (RH) CONNECTOR CONDITION
  • Disconnect the brake light (RH) connector.
  • Inspect the connector engagement and connection condition and inspect the terminals for damage, deformation, corrosion, or disconnection.
  • Is the connector normal?
 Yes Go to the next step.
No Repair or replace the connector, then go to Step 17.
7 INSPECT REAR BODY CONTROL MODULE (RBCM) CONNECTOR CONDITION
  • Disconnect the rear body control module (RBCM) connector.
  • Inspect the connector engagement and connection condition and inspect the terminals for damage, deformation, corrosion, or disconnection.
  • Is the connector normal?
 Yes Go to the next step.
No Repair or replace the connector, then go to Step 17.
8 INSPECT FOR SHORT TO GROUND IN BRAKE LIGHT CIRCUIT
  • Verify that the high-mount brake light, brake light (LH), brake light (RH) and rear body control module (RBCM) connectors are disconnected.
  • Inspect for continuity between rear body control module (RBCM) terminal 4D (wiring harness-side) and body ground.
  • Is there continuity?
 Yes Refer to the wiring diagram and verify whether or not there is a common connector between the following terminals:
  • Rear body control module (RBCM) terminal 4D-Brake light (LH) terminal C
  • Rear body control module (RBCM) terminal 4D-Brake light (RH) terminal C
  • Rear body control module (RBCM) terminal 4D-High-mount brake light terminal B

    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 ground.
  • Repair or replace the malfunctioning part.

    If there is no common connector:

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

Go to Step 17.
No Go to the next step.
9 INSPECT FOR SHORT TO POWER SUPPLY IN BRAKE LIGHT CIRCUIT
  • Verify that the high-mount brake light, brake light (LH), brake light (RH) and rear body control module (RBCM) connectors are disconnected.
  • Reconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)
  • Switch the ignition ON (engine off or on).
  • Measure the voltage at the rear body control module (RBCM) terminal 4D (wiring harness-side).
  • Is the voltage 0 V?
 Yes Go to the next step.
No Refer to the wiring diagram and verify whether or not there is a common connector between the following terminals:
  • Rear body control module (RBCM) terminal 4D-Brake light (LH) terminal C
  • Rear body control module (RBCM) terminal 4D-Brake light (RH) terminal C
  • Rear body control module (RBCM) terminal 4D-High-mount brake light terminal B

    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 17.
10 INSPECT FOR OPEN CIRCUIT IN BRAKE LIGHT CIRCUIT
  • Verify that the high-mount brake light, brake light (LH), brake light (RH) and rear body control module (RBCM) connectors are disconnected.
  • Switch the ignition off.
  • Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)
  • Inspect for continuity between the following terminals (wiring harness-side):
    • Rear body control module (RBCM) terminal 4D-Brake light (LH) terminal C
    • Rear body control module (RBCM) terminal 4D-Brake light (RH) terminal C
      • Rear body control module (RBCM) terminal 4D-High-mount brake light terminal B
  • 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 the following terminals:
  • Rear body control module (RBCM) terminal 4D-Brake light (LH) terminal C
  • Rear body control module (RBCM) terminal 4D-Brake light (RH) terminal C
  • Rear body control module (RBCM) terminal 4D-High-mount brake light terminal B

    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 17.
11 INSPECT FOR SHORT TO GROUND IN HIGH-MOUNT BRAKE LIGHT
  • Verify that the high-mount brake light, brake light (LH), brake light (RH) and rear body control module (RBCM) connectors are disconnected.
  • Reconnect the high-mount brake light connector.
  • Inspect for continuity between rear body control module (RBCM) terminal 4D (wiring harness-side) and body ground.
  • Is there continuity?
 Yes Replace the high-mount brake light, then go to Step 17.
(See HIGH-MOUNT BRAKE LIGHT REMOVAL/INSTALLATION .)
No Go to the next step.
12 INSPECT FOR SHORT TO POWER SUPPLY IN HIGH-MOUNT BRAKE LIGHT
  • Verify that the brake light (LH), brake light (RH) and rear body control module (RBCM) connectors are disconnected.
  • Reconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)
  • Switch the ignition ON (engine off or on).
  • Measure the voltage at the rear body control module (RBCM) terminal 4D (wiring harness-side).
  • Is the voltage 0 V?
 Yes Brake light (bulb type)
  • Go to Step 17.

    Brake light (LED type)

  • Go to the next step.
No Replace the high-mount brake light, then go to Step 17.
(See HIGH-MOUNT BRAKE LIGHT REMOVAL/INSTALLATION .)
13 INSPECT FOR SHORT TO GROUND IN BRAKE LIGHT (LH)
  • Verify that the brake light (LH), brake light (RH) and rear body control module (RBCM) connectors are disconnected.
  • Switch the ignition off.
  • Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)
  • Reconnect the brake light (LH) connector.
  • Inspect for continuity between rear body control module (RBCM) terminal 4D (wiring harness-side) and body ground.
  • Is there continuity?
 Yes Replace the rear combination light (LH), then go to Step 17.
(See REAR COMBINATION LIGHT REMOVAL/INSTALLATION .)
No Go to the next step.
14 INSPECT FOR SHORT TO POWER SUPPLY IN BRAKE LIGHT (LH) Yes Go to the next step.
No Replace the rear combination light (LH), then go to Step 17.
(See REAR COMBINATION LIGHT REMOVAL/INSTALLATION .)
15 INSPECT FOR SHORT TO GROUND IN BRAKE LIGHT (RH)
  • Verify that the brake light (RH) and rear body control module (RBCM) connectors are disconnected.
  • Switch the ignition off.
  • Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)
  • Reconnect the brake light (RH) connector.
  • Inspect for continuity between rear body control module (RBCM) terminal 4D (wiring harness-side) and body ground.
  • Is there continuity?
 Yes Replace the rear combination light (RH), then go to Step 17.
(See REAR COMBINATION LIGHT REMOVAL/INSTALLATION .)
No Go to the next step.
16 INSPECT FOR SHORT TO POWER SUPPLY IN BRAKE LIGHT (RH) Yes Go to the next step.
No Replace the rear combination light (RH), then go to the next step.
(See REAR COMBINATION LIGHT REMOVAL/INSTALLATION .)
17 VERIFY THAT REPAIRS HAVE BEEN COMPLETED Yes Repeat the inspection from Step 1.
Go to the next step.
No Go to the next step.
18 VERIFY IF OTHER DTCs DISPLAYED
  • Are any other DTCs displayed?
 Yes Repair or replace the malfunctioning part according to the applicable DTC troubleshooting.
(See DTC TABLE [REAR BODY CONTROL MODULE (RBCM)] .)
No DTC troubleshooting completed.
scientia non olet · About LEMON Manuals