DTC C0023:14 [REAR BODY CONTROL MODULE (RBCM)]

< Previous Next >

2014 - Mazda6 - Body and Accessories

DTC C0023:14 [REAR BODY CONTROL MODULE (RBCM)]

Without Mazda Radar Cruise Control (MRCC) System


Description	Brake light circuit malfunction
Detection condition	Rear body control module (RBCM) detects any of the following conditions: Brake lights/high-mount brake light illuminated even though driver or system does not illuminate brake lights/high-mount brake lights. Brake lights/high-mount brake light not illuminated even though driver depresses brake pedal. Brake lights/high-mount brake light not illuminated even though system illuminates brake lights/high-mount brake light.
Fail-safe function	Not applicable
Possible cause	High-mount brake light connector or terminal malfunction Brake light (LH) connector or terminal malfunction Brake light (RH) connector or terminal malfunction Rear body control module (RBCM) connector or terminal malfunction Short to ground in brake light circuit Short to power supply in brake light circuit Open circuit in brake light circuit High-mount brake light malfunction Brake light (LH) malfunction Brake light (RH) malfunction Rear body control module (RBCM) malfunction

Diagnostic Procedure


Step	Inspection		Action
1	VERIFY REAR BODY CONTROL MODULE (FBCM) DTCs AGAIN Clear the DTC for the rear body control module (RBCM) using the M-MDS. (See CLEARING DTC [REAR BODY CONTROL MODULE (RBCM)].) Depress the brake pedal. Retrieve the rear body control module (RBCM) DTCs using the M-MDS. (See DTC INSPECTION [REAR BODY CONTROL MODULE (RBCM)].) Is the same DTC displayed?	Yes	Go to the next step.
1		No	Go to Step 16.
2	INSPECT HIGH-MOUNT BRAKE LIGHT CONNECTOR Switch the ignition off. Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.5].) Disconnect the high-mount brake light 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.
2		No	Repair or replace the connector, then go to Step 15.
3	INSPECT BRAKE LIGHT (LH) CONNECTOR 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.
3		No	Repair or replace the connector, then go to Step 15.
4	INSPECT BRAKE LIGHT (RH) CONNECTOR 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.
4		No	Repair or replace the connector, then go to Step 15.
5	INSPECT REAR BODY CONTROL MODULE (RBCM) CONNECTOR 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.
5		No	Repair or replace the connector, then go to Step 15.
6	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 15.
6		No	Go to the next step.
7	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 2.5].) 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.
7		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 15.
8	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 2.5].) Inspect for continuity between rear body control module (RBCM) terminal 4D (wiring harness-side) and brake light (LH) terminal C (wiring harness-side). Is there continuity?	Yes	Go to the next step.
8		No	Refer to the wiring diagram and verify whether or not there is a common connector between rear body control module (RBCM) terminal 4D and brake light (LH) terminal C. 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 15.
9	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 15. (See HIGH-MOUNT BRAKE LIGHT REMOVAL/INSTALLATION.)
9		No	Go to the next step.
10	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 2.5].) 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.
10		No	Replace the high-mount brake light, then go to Step 15. (See HIGH-MOUNT BRAKE LIGHT REMOVAL/INSTALLATION.)
11	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 2.5].) 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 15. (See REAR COMBINATION LIGHT REMOVAL/INSTALLATION.)
11		No	Go to the next step.
12	INSPECT FOR SHORT TO POWER SUPPLY IN BRAKE LIGHT (LH) Verify that the 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 2.5].) 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.
12		No	Replace the rear combination light (LH), then go to Step 15. (See REAR COMBINATION LIGHT REMOVAL/INSTALLATION.)
13	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 2.5].) 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 15. (See REAR COMBINATION LIGHT REMOVAL/INSTALLATION.)
13		No	Go to the next step.
14	INSPECT FOR SHORT TO POWER SUPPLY IN BRAKE LIGHT (RH) Verify that the rear body control module (RBCM) connector is disconnected. Reconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [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.
14		No	Replace the rear combination light (RH), then go to the next step. (See REAR COMBINATION LIGHT REMOVAL/INSTALLATION.)
15	VERIFY THAT REPAIRS HAVE BEEN COMPLETED Always reconnect all disconnected connectors. Reconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.5].) Clear the DTC for the rear body control module (RBCM) using the M-MDS. (See CLEARING DTC [REAR BODY CONTROL MODULE (RBCM)].) Depress the brake pedal. Retrieve the rear body control module (RBCM) DTCs using the M-MDS. (See DTC INSPECTION [REAR BODY CONTROL MODULE (RBCM)].) Is the same DTC displayed?	Yes	Repeat the inspection from Step 1. If the malfunction recurs, replace the rear body control module (RBCM). (See REAR BODY CONTROL MODULE (RBCM) REMOVAL/INSTALLATION.) Go to the next step.
15		No	Go to the next step.
16	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)].)
16		No	DTC troubleshooting completed.

With Mazda Radar Cruise Control (MRCC) System


Description	Brake light circuit malfunction
Detection condition	Rear body control module (RBCM) detects any of the following conditions: Brake lights/high-mount brake light illuminated even though driver or system does not illuminate brake lights/high-mount brake lights. Brake lights/high-mount brake light not illuminated even though driver depresses brake pedal. Brake lights/high-mount brake light not illuminated even though system illuminates brake lights/high-mount brake light.
Fail-safe function	Not applicable
Possible cause	Brake light (LH) connector or terminal malfunction Brake light (RH) connector or terminal malfunction Brake light unit connector or terminal malfunction Rear body control module (RBCM) connector or terminal malfunction Short to ground in brake light circuit Short to power supply in brake light circuit Open circuit in brake light circuit Brake light unit malfunction Brake light (LH) malfunction Brake light (RH) malfunction Rear body control module (RBCM) malfunction

Diagnostic Procedure


Step	Inspection		Action
1	VERIFY REAR BODY CONTROL MODULE (FBCM) DTCs AGAIN Clear the DTC for the rear body control module (RBCM) using the M-MDS. (See CLEARING DTC [REAR BODY CONTROL MODULE (RBCM)].) Depress the brake pedal. Retrieve the rear body control module (RBCM) DTCs using the M-MDS. (See DTC INSPECTION [REAR BODY CONTROL MODULE (RBCM)].) Is the same DTC displayed?	Yes	Go to the next step.
1		No	Go to Step 15.
2	INSPECT BRAKE LIGHT (LH) CONNECTOR Switch the ignition off. Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.5].) 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.
2		No	Repair or replace the connector, then go to Step 14.
3	INSPECT BRAKE LIGHT (RH) CONNECTOR 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.
3		No	Repair or replace the connector, then go to Step 14.
4	INSPECT BRAKE LIGHT UNIT CONNECTOR Disconnect the brake light unit 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.
4		No	Repair or replace the connector, then go to Step 14.
5	INSPECT REAR BODY CONTROL MODULE (RBCM) CONNECTOR 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.
5		No	Repair or replace the connector, then go to Step 14.
6	INSPECT FOR SHORT TO GROUND IN BRAKE LIGHT CIRCUIT Verify that the brake light (LH), brake light (RH), brake light unit 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—Brake light unit terminal J 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 14.
6		No	Go to the next step.
7	INSPECT FOR SHORT TO POWER SUPPLY IN BRAKE LIGHT CIRCUIT Verify that the brake light (LH), brake light (RH), brake light unit and rear body control module (RBCM) connectors are disconnected. Reconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [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.
7		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—Brake light unit terminal J 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 14.
8	INSPECT FOR OPEN CIRCUIT IN BRAKE LIGHT CIRCUIT Verify that the brake light (LH), brake light (RH), brake light unit 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 2.5].) Inspect for continuity between rear body control module (RBCM) terminal 4D (wiring harness-side) and brake light (LH) terminal C (wiring harness-side). Is there continuity?	Yes	Go to the next step.
8		No	Refer to the wiring diagram and verify whether or not there is a common connector between rear body control module (RBCM) terminal 4D and brake light (LH) terminal C. 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 14.
9	INSPECT BRAKE LIGHT UNIT Inspect the brake light unit. (See BRAKE LIGHT UNIT INSPECTION.) Is the brake light unit normal?	Yes	Go to the next step.
9		No	Replace the brake light unit, then go to Step 14. (See BRAKE LIGHT UNIT REMOVAL/INSTALLATION.)
10	INSPECT FOR SHORT TO GROUND IN BRAKE LIGHT (LH) Verify that the brake light (LH), brake light (RH), brake light unit and rear body control module (RBCM) connectors are disconnected. 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 14. (See REAR COMBINATION LIGHT REMOVAL/INSTALLATION.)
10		No	Go to the next step.
11	INSPECT FOR SHORT TO POWER SUPPLY IN BRAKE LIGHT (LH) Verify that the brake light (RH), brake light unit and rear body control module (RBCM) connectors are disconnected. Reconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [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.
11		No	Replace the rear combination light (LH), then go to Step 14. (See REAR COMBINATION LIGHT REMOVAL/INSTALLATION.)
12	INSPECT FOR SHORT TO GROUND IN BRAKE LIGHT (RH) Verify that the brake light (RH), brake light unit 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 2.5].) 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 14. (See REAR COMBINATION LIGHT REMOVAL/INSTALLATION.)
12		No	Go to the next step.
13	INSPECT FOR SHORT TO POWER SUPPLY IN BRAKE LIGHT (RH) Verify that the brake light unit and rear body control module (RBCM) connectors are disconnected. Reconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [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.
13		No	Replace the rear combination light (RH), then go to the next step. (See REAR COMBINATION LIGHT REMOVAL/INSTALLATION.)
14	VERIFY THAT REPAIRS HAVE BEEN COMPLETED Always reconnect all disconnected connectors. Reconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.5].) Clear the DTC for the rear body control module (RBCM) using the M-MDS. (See CLEARING DTC [REAR BODY CONTROL MODULE (RBCM)].) Depress the brake pedal. Retrieve the rear body control module (RBCM) DTCs using the M-MDS. (See DTC INSPECTION [REAR BODY CONTROL MODULE (RBCM)].) Is the same DTC displayed?	Yes	Repeat the inspection from Step 1. If the malfunction recurs, replace the rear body control module (RBCM). (See REAR BODY CONTROL MODULE (RBCM) REMOVAL/INSTALLATION.) Go to the next step.
14		No	Go to the next step.
15	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)].)
15		No	DTC troubleshooting completed.

< Previous Next >