DTC Troubleshooting: C0023-14 (5-door) - Honda Civic FC/FK 2016-2021

1.

Problem verification:

Problem verification

?1.	Turn the vehicle to the ON mode.

?2.	Clear the DTC with the HDS.

?3.	Turn the vehicle to the OFF (LOCK) mode, then to the ON mode.

?4.

Check for DTCs with the HDS.

DTC Description	DTC	Freeze Frame
C0023-14 Brake Diag Circuit OFF Failure

Is DTC C0023-14 indicated?


	YES

The failure is duplicated. Go to step 2.


	NO

Intermittent failure, the system is OK at this time. Refer to intermittent failures troubleshooting. If the freeze data/on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the Freeze data/on-board snapshot.?

2.

Fuse check

?1.	Turn the vehicle to the OFF (LOCK) mode.

?2.

Check the following fuse.

Fuse	No. A8 (10 A)
Location	Under-hood fuse/relay box

Is the fuse OK?


	YES

The fuse is OK. Reinstall the fuse, then go to step 3.


	NO

Replace the fuse. If the fuse blows again, repair the short to body ground on the No. A8 (10 A) fuse circuit.?

3.

Open wire check (BRK LAMP line) 1:

Open wire check (BRK LAMP line) 1

?1.	Turn the vehicle to the OFF (LOCK) mode.

?2.

Disconnect the following connector.

VSA modulator-control unit 46P connector

?3.

Connect terminals 1 and 2 with a jumper wire.

Terminal 1	VSA modulator-control unit 46P connector No. 34
Terminal 2	Body ground

?4.	Turn the vehicle to the ON mode.

?5.	Check the brake lights without pressing the brake pedal.

Are the brake lights on?


	YES

Go to step 7.


	NO

Go to step 4.

4.

Open wire check (BRK LAMP line) 2:

Open wire check (BRK LAMP line) 2

?1.	Turn the vehicle to the OFF (LOCK) mode.

?2.	Disconnect the jumper wire.

?3.

Disconnect the following connector.

Relay circuit board connector B (6P) (built-in brake light relay)

?4.

Check for continuity between test points 1 and 2.

Test condition	Vehicle OFF (LOCK) mode
	VSA modulator-control unit 46P connector: disconnected
	Relay circuit board connector B (6P): disconnected
Test point 1	Relay circuit board connector B (6P) (female terminals) No. 1:
Test point 2	VSA modulator-control unit 46P connector No. 34

Is there continuity?


	YES

The BRK LAMP wire is OK. Go to step 5.


	NO

Repair an open in the wire between the VSA modulator-control unit and the relay circuit board (built-in brake light relay).?

5.

Open wire check (IG1 OPTION line):

Open wire check (IG1 OPTION line)

?1.

Disconnect the following connector.

Relay circuit board connector A (8P) (built-in brake light relay)

?2.	Turn the vehicle to the ON mode.

?3.

Measure the voltage between test points 1 and 2.

Test condition	Vehicle ON mode
	VSA modulator-control unit 46P connector: disconnected
	Relay circuit board connector A (8P): disconnected
	Relay circuit board connector B (6P): disconnected
Test point 1	Relay circuit board connector A (8P) (female terminals) No. 3:
Test point 2	Body ground

Is there battery voltage?


	YES

The IG1 OPTION wire is OK. Go to step 6.


	NO

Repair an open in the wire between the No. B5 (10 A) fuse in the under-dash fuse/relay box and the relay circuit board (built-in brake light relay).?

6.

Open wire check (+B STOP line):

Open wire check (+B STOP line)

?1.	Turn the vehicle to the OFF (LOCK) mode.

?2.

Disconnect the following connector.

Relay circuit board connector C (18P) (built-in brake light relay)

?3.

Check for continuity between test points 1 and 2.

Test condition	Vehicle OFF (LOCK) mode
	Relay circuit board connector A (8P): disconnected
	Relay circuit board connector B (6P): disconnected
	Relay circuit board connector C (18P): disconnected
Test point 1	Relay circuit board connector C (18P) (female terminals) No. 4:
Test point 2	Body ground

Is there battery voltage?


	YES

The +B STOP is OK. Go to step 7.


	NO

Repair an open in the wire between the No. A8 (10 A) fuse in the under-hood fuse/relay box and the relay circuit board (built-in brake light relay).?

7.

Open wire check (BRK DIAG line):

Open wire check (BRK DIAG line)

?1.	Turn the vehicle to the OFF (LOCK) mode.

?2.	Disconnect the jumper wire (if installed).

?3.

Disconnect the following connector (if connected).

VSA modulator-control unit 46P connector

Relay circuit board connector A (8P) (built-in brake light relay)

?4.

Check for continuity between test points 1 and 2.

Test condition	Vehicle OFF (LOCK) mode
	Relay circuit board connector A (8P): disconnected
	Relay circuit board connector B (6P): connected or disconnected
	Relay circuit board connector C (18P): connected or disconnected
	VSA modulator-control unit 46P connector: disconnected
Test point 1	Relay circuit board connector A (8P) (female terminals) No. 6:
Test point 2	VSA modulator-control unit 46P connector No. 30

Is there continuity?


	YES

The BRK DIAG wire is OK. Go to step 8.


	NO

Repair an open in the wire between the VSA modulator-control unit and the relay circuit board (built-in brake light relay).?

8.

Brake light relay check (substitution):

Brake light relay check (substitution)

?1.	Substitute a known-good relay circuit board (built-in brake light relay).

?2.

Reconnect the following connectors.

Relay circuit board connector A (8P)

Relay circuit board connector B (6P) (if disconnected)

Relay circuit board connector C (18P) (if disconnected)

VSA modulator-control unit 46P connector

?3.	Turn the vehicle to the ON mode.

?4.	Clear the DTC with the HDS.

?5.	Turn the vehicle to the OFF (LOCK) mode, then to the ON mode.

?6.

Check for DTCs with the HDS.

DTC Description	DTC	Freeze Frame
C0023-14 Brake Diag Circuit OFF Failure

Is DTC C0023-14 indicated?


	YES

Check for loose terminals and poor connections in the VSA modulator-control unit 46P connector. Check for any authorized service information related to the DTCs or symptoms you are troubleshooting. If they are OK, replace the VSA modulator-control unit.?


	NO

Replace the original relay circuit board (built-in brake light relay).?