DTC B1279: Headlight Switch DIMMER Position Circuit Malfunction

WARNING: This page is about a different car, the 2013 Honda Fit, 2012 Honda Fit, 2011 Honda Fit, 2010 Honda Fit, and 2009 Honda Fit. However, it is still accessible from the selected car via links, so may be relevant.

Clear the DTCs with the HDS.
Turn the ignition switch to LOCK (0) and then back to ON (II).
Turn the combination light (headlight) switch ON.
Change the dimmer switch from low beam to high beam.
Turn the combination light switch OFF and then to the passing position, and wait for at least 6 seconds.
Check for DTCs with the HDS.
Is DTC B1279 indicated?

YES - Go to step 7.

NO - Intermittent failure, the system is OK at this time. Check for loose or poor connections.
Select LIGHTING from the BODY ELECTRICAL system select menu, then enter the DATA LIST.

Check each combination light switch position value with the DATA LIST menu.

When the passing switch is operated

DATA LIST TABLE

Data List	Value
Headlight Switch (PASSING)	ON
Headlight Switch (High beam)	OFF

When the headlight switch is turned ON, and the dimmer switch changed from low beam to high beam

DATA LIST TABLE

Data List	Value
Headlight Switch (PASSING)	OFF
Headlight Switch (High beam)	ON
Headlight Switch (HEADLIGHT)	ON

Are all data list values correct?

YES - Faulty MICU; replace the under-dash fuse/relay box:

For USA models (see USA MODELS )
For Canada models (see CANADA MODELS )

NO - Go to step 9.

Turn the ignition switch to LOCK (0).
Disconnect the combination light switch 12P connector.
Turn the ignition switch to ON (II).
Select LIGHTING from the BODY ELECTRICAL system select menu, then enter the DATA LIST.

Check each combination light switch position value with the DATA LIST menu.

When the combination light switch is turned OFF

DATA LIST TABLE

Data List	Value
Headlight Switch (PASSING)	OFF
Headlight Switch (High beam)	OFF
Headlight Switch (HEADLIGHT)	OFF

Are all data list values indicated OFF?

YES - Go to step 17.

NO - Go to step 14.

Turn the ignition switch to LOCK (0).
Disconnect under-dash fuse/relay box connector M (34P).
Check for continuity between under-dash fuse/relay box connector M (34P) terminals No. 3, No. 4, and No. 5 and body ground individually.
Is there continuity?

YES - Repair short to ground in the wires.

NO - Faulty MICU; replace the under-dash fuse/relay box:
- For USA models (see USA MODELS )
- For Canada models (see CANADA MODELS )
Fig 1: Checking Continuity Between Under-Dash Fuse/Relay Box Connector M (34P) Terminals 3, 4, 5 & Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Turn the ignition switch to LOCK (0).
Do the combination light switch test (see COMBINATION LIGHT SWITCH TEST/REPLACEMENT ).
Is the combination light switch OK?

YES - Go to step 19.

NO - Replace the combination light switch.
Disconnect under-dash fuse/relay box connector M (34P).

Check for continuity between under-dash fuse/relay box connector M (34P) terminals and the combination light switch 12P connector terminals as shown:

CONNECTOR TERMINAL REFERENCE TABLE

Under-dash fuse/ relay box connector M (34P)	Combination light switch 12P connector
3	4
4	6
5	10
33	12

Is there continuity?

YES - Go to step 21.

NO - Repair open in the wire.

Fig 2: Checking Continuity Between Under-Dash Fuse/Relay Box Connector M (34P) Terminals & Combination Light Switch 12P Connector Terminals

Courtesy of AMERICAN HONDA MOTOR CO., INC.

Check for continuity between under-dash fuse/relay box connector M (34P) terminals as shown:

CONTINUITY REFERENCE TABLE

From terminal	To terminal
5	3, 4, 7, 8
7	3, 4, 8
8	3, 4

Is there continuity?

YES - Repair short between the wires.

NO - Faulty MICU; replace the under-dash fuse/relay box:

For USA models (see USA MODELS )
For Canada models (see CANADA MODELS )