DTC : B1279

DTC B1279  : Dimmer switch circuit malfunction

DTC (MICU)

NOTE:  If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A - Refer to: Body Electrical Troubleshooting - B-CAN System Diagnosis Test Mode A - Initial Communication and DTC Checks .

1. Exterior lights system check 1

   -1. With the headlight dimmer switch in the neutral position, check the parameter(s) below with the HDS.

   Signal	Current conditions
   	Values	Unit
   Headlight Switch (HIGH BEAM)
   Headlight Switch (PASSING)

   Is either information indicator ON?

   YES 

   Go to step 4.

   NO 

   Go to step 2.

2. Exterior lights system check 2

   -1. With the headlight dimmer switch in the high beam position, check the parameter(s) below with the HDS.

   Signal	Current conditions
   	Values	Unit
   Headlight Switch (HIGH BEAM)
   Headlight Switch (PASSING)

   Are both information indicators ON?

   YES 

   Go to step 3.

   NO 

   Intermittent failure, the system is OK at this time.

3. Shorted wire check (H/L HI SW to PASSING SW line)

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

   - 2. Disconnect the following connector.

   Combination light switch 12P connector

   - 3. Connect terminals A and B with a jumper wire.

   Terminal A	Under-Dash Fuse/Relay Box Connector N (20P) No. 16
   Terminal B	Body ground

   - 4. Check the parameter(s) below with the HDS.

   Signal	Current conditions
   	Values	Unit
   Headlight Switch (HIGH BEAM)
   Headlight Switch (PASSING)

   Are both information indicators ON?

   YES 

   Repair a short between the wires.

   NO 

   The H/L HI SW to PASSING SW wire is OK. Replace the Combination Light Switch - Removal and Installation .

4. Determine possible failure area (combination light switch, others)

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

   - 2. Disconnect the following connector.

   Combination light switch 12P connector

   - 3. Check the parameter(s) below with the HDS.

   Signal	Current conditions
   	Values	Unit
   Headlight Switch (HIGH BEAM)
   Headlight Switch (PASSING)

   Is either information indicator ON?

   YES 

   Go to step 5.

   NO 

   Replace the Combination Light Switch - Removal and Installation .

5. Shorted wire check (PASSING SW, H/L HI SW lines)

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

   - 2. Disconnect the following connector.

   Under-dash fuse/relay box connector N (20P)

   - 3. Check for continuity between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode Combination light switch 12P connector: disconnected Under-dash fuse/relay box connector N (20P): disconnected
   Test point 1	Under-Dash Fuse/Relay Box Connector N (20P) No. 17
   Test point 2	Body ground

   Test point 1	Under-Dash Fuse/Relay Box Connector N (20P) No. 16
   Test point 2	Body ground

   Are there continuity?

   YES 

   Repair a short to ground in the wire.

   NO 

   The PASSING SW and DIMMER SW wires are OK. Faulty MICU; replace the Under-Dash Fuse/Relay Box - Removal and Installation .