FRONT SEAT WARMER CONTROL UNIT INSPECTION

id091300701900

Warning
•  Handling a front seat (with built-in side air bag) improperly can accidentally operate (deploy) the air bag, which may seriously injure you. Read the service warnings before handling a front seat (with built-in side air bag). (See AIR BAG SYSTEM SERVICE WARNINGS.) (See AIR BAG SYSTEM SERVICE CAUTIONS.)
Caution
•  After removing a front seat, do not operate the slider lever. If the slider lever is operated, the left and right slide positions will deviate, and the slide adjuster may be damaged after the front seat is installed.
•  Verify that there are no malfunctions in the sliding mechanism after installing a front seat.
•  When performing the procedure with a front seat removed from the vehicle, perform the procedure on a clean rag so as not to damage or soil the seat.

Forward

•  When performing an asterisked (*) troubleshooting inspection, shake the wiring harness and connectors while performing the inspection to discover whether poor contact points are the cause of any intermittent malfunction. If there is a problem, inspect to make sure connectors, terminals and wiring harnesses are connected correctly and undamaged.

System Diagram

am6zzw00013471

Symptom Trouble Shooting Index

No.

Troubleshooting item

Description
1
Front seat warmer function is inoperative (See Inspection Procedure (No.1 Front Seat Warmer Function Is Inoperative).)
Front seat warmer does not warm seat even though front seat warmer switch is on
2
Front seat warmer always operations (See Inspection Procedure (No.2 Front Seat Warmer Always Operations).)
Front seat warmer warms seat even though front seat warmer switch is off


Inspection Procedure (No.1 Front Seat Warmer Function Is Inoperative)

No.1

Front seat warmer function is inoperative
DETECTION
Front seat warmer does not warm seat even though front seat warmer switch is on
POSSIBLE CAUSE
The power supply is not supplied to filament of front seat warmer
•  Open circuit in front seat warmer control unit power supply circuit:
―  Front seat warmer control unit terminal O and battery positive terminal
―  Front seat warmer control unit terminal M and battery positive terminal
•  SEAT WARM 20 A fuse malfunction (Blown fuse):
―  Front seat warmer control unit terminal O and battery positive terminal
―  Front seat warmer control unit terminal M and battery positive terminal
•  Poor connect the connector:
―  Driver-side front seat warmer unit connector and front seat warmer control unit connector
―  Passenger-side front seat warmer unit connector and front seat warmer control unit connector
•  Open circuit in wiring harness between the following terminal:
―  Driver-side front seat warmer unit terminal P and driver-side front seat warmer unit terminal A
―  Passenger-side front seat warmer unit terminal N and passenger-side front seat warmer unit terminal B
Front seat warmer control unit not operation
•  Open circuit or short to ground in wiring harness between the following terminal:
―  FBCM terminal 1C and front seat warmer control unit terminal K
―  Front seat warmer control unit terminal H and body ground
―  Front seat warmer control unit terminal G and body ground
Front seat warmer unit cannot control filament on
•  Front seat warmer unit malfunction
Front seat warmer filament does not generate heat
•  Driver-side front seat warmer unit (seat cushion side) malfunction
•  Driver-side front seat warmer unit (seat back side) malfunction
•  Passenger-side front seat warmer unit (seat cushion side) malfunction
•  Passenger-side front seat warmer unit (seat back side) malfunction
Front seat warmer control unit cannot receive operation signal
•  Front seat warmer control unit malfunction
•  Open circuit or short to ground in wiring harness between the following terminal:
―  Front seat warmer control unit terminal I and indicator unit terminal D

Diagnostic procedure

STEP

INSPECTION

ACTION
1
PERFORM DTC INSPECTION
•  Verify the instrument cluster DTC inspection.
•  Are DTCs and error codes output?
Yes
Perform the diagnosis according to the inspection procedure for each code.
(See DTC TABLE [INSTRUMENT CLUSTER].)
No
Go to the next step.
2
DETERMINE IF THE MALFUNCTION CAUSE IS THE FRONT SEAT WARMER SWITCH
•  Select either Low, Mid, or High on the front seat warmer switch.
•  Does the front seat warmer switch LED illuminate?
Yes
Go to the next step.
No
Inspect the indicator unit.
(See INDICATOR UNIT INSPECTION.)
3
DETERMINE MALFUNCTIONING SYSTEM
•  Does either the left or right front seat warmer operate?
Yes
Go to step 9.
No
Go to the next step.
4
INSPECT THE FRONT SEAT WARMER CONTROL UNIT POWER SUPPLY FUSE
•  Inspect the SEAT WARM 20 A fuse.
•  Is the fuse normal?
Yes
Go to the next step.
No
•  If the fuse is deterioration:
―  Replace the malfunctioning fuse.
•  If the fuse is blown
Repair the short to ground in wiring harness between the following terminals:
―  SEAT WARM 20 A fuse and front seat warmer control unit terminal O
―  SEAT WARM 20 A fuse and front seat warmer control unit terminal M
5*
DETERMINE IF CAUSE OF MALFUNCTION IS CONTROLLER POWER SUPPLY WIRING HARNESS FOR FRONT SEAT WARMER OR OTHER CAUSE
•  Switch the ignition off (LOCK).
•  Disconnect the front seat warmer control unit connector.
•  Measure the voltage at the following terminal (wiring harness-side):
―  Front seat warmer control unit terminal O
―  Front seat warmer control unit terminal M
•  Is the voltage B+?
Yes
Go to the next step.
No
•  Repair or replace the open circuit at the following wiring harness.
―  SEAT WARM 20 A fuse and front seat warmer control unit terminal O
―  SEAT WARM 20 A fuse and front seat warmer control unit terminal M
6*
VERIFY IF MALFUNCTION CAUSE IS OPEN CIRCUIT IN FRONT SEAT WARMER CONTROL UNIT POWER SUPPLY WIRING HARNESS
•  Front seat warmer control unit connector are disconnected.
•  Switch the ignition ON (engine off or on).
•  Measure the voltage at the following terminal (wiring harness-side):
―  Front seat warmer control unit terminal K
•  Is the voltage B+?
Yes
Go to the next step.
No
•  Inspect the FBCM terminal 1C. (See FRONT BODY CONTROL MODULE (FBCM) INSPECTION.)
•  Repair or replace the open circuit at the following wiring harness.
―  FBCM terminal 1C and front seat warmer control unit terminal K
7*
INSPECT FOR OPEN CIRCUIT IN FRONT SEAT WARMER CONTROL UNIT GROUND CIRCUIT
•  Front seat warmer control unit connector on the side that is not operating is disconnected.
•  Inspect for continuity between the following terminals (wiring harness-side):
―  Front seat warmer control unit terminal on the side that is not operating H and body ground
―  Front seat warmer control unit terminal on the side that is not operating G and body ground
•  Is there continuity?
Yes
Go to the next step.
No
•  Inspect the open circuit following.
―  Front seat warmer unit terminal H and body ground
―  Front seat warmer unit terminal G and body ground
•  Inspect the body ground connector terminals for poor connection.
•  Repair or replace the malfunction.
8*
VERIFY IF MALFUNCTION CAUSE IS OPEN CIRCUIT IN WIRING HARNESS OF FRONT SEAT WARMER SWITCH SIGNAL
•  Front seat warmer control unit connector is disconnected.
•  Inspect for continuity between the following terminals (wiring harness-side):
•  Front seat warmer control unit terminal I and indicator unit terminal D
•  Is there continuity?
Yes
Go to the next step.
No
•  Inspect the open circuit following.
―  Front seat warmer control unit terminal I and indicator unit terminal D
9*
INSPECT FRONT SEAT WARMER CONTROL UNIT AND FRONT SEAT WARMER UNIT CONNECTOR
•  Disconnect the front seat warmer control unit and front seat warmer unit connector on the side not operating.
•  Inspect the front seat warmer control unit and front seat warmer unit connector terminals for poor connection (such as damaged/pulled-out pins, and corrosion).
•  Is there any malfunction?
Yes
Repair or replace the malfunctions.
No
Go to the next step.
10*
VERIFY IF MALFUNCTION CAUSE IS OPEN CIRCUIT IN WIRING HARNESS OF FRONT SEAT WARMER UNIT CIRCUIT
•  Switch the ignition off (LOCK).
•  Disconnect the front seat warmer control unit connector.
•  Inspect for continuity between the following terminals (wiring harness-side):
―  Driver-side front seat warmer unit terminal P and A
―  Passenger-side front seat warmer unit terminal N and B
•  Is there continuity?
Yes
Go to the next step.
No
Replace the front seat back pad or front seat cushion pad.
(See FRONT SEAT BACK TRIM REMOVAL/INSTALLATION.)
(See FRONT SEAT CUSHION TRIM REMOVAL/INSTALLATION.)
11
DETERMINE IF THE MALFUNCTION CAUSE IS FRONT SEAT WARMER CONTROL UNIT
•  Replace the indicator unit.
•  Does the front seat warmer system operate?
Yes
Troubleshooting completed.
No
Replace the front seat back pad or front seat cushion pad.
(See FRONT SEAT BACK TRIM REMOVAL/INSTALLATION.)
(See FRONT SEAT CUSHION TRIM REMOVAL/INSTALLATION.)


Inspection Procedure (No.2 Front Seat Warmer Always Operations)

No.2

Front seat warmer always operations
DETECTION
Front seat warmer warms seat even though front seat warmer switch is off
POSSIBLE CAUSE
•  Short circuit in wiring harness between the following terminal.
―  Front seat warmer control unit terminal N and passenger-side front seat warmer unit terminal G
―  Front seat warmer control unit terminal P and driver-side front seat warmer unit terminal 6B
•  Passenger-side front seat warmer unit malfunction
•  Driver-side front seat warmer unit malfunction
•  Indicator unit malfunction
•  Front seat warmer control unit malfunction

Diagnostic procedure

STEP

INSPECTION

ACTION
1*
INSPECT FRONT SEAT WARMER UNIT CIRCUIT FOR SHORT TO POWER SUPPLY
•  Disconnect the front seat warmer control unit connector.
•  Measure the voltage between passenger-side front seat warmer unit terminal G and body ground.
•  Measure the voltage between driver-side front seat warmer unit terminal 6B and body ground.
•  Is the voltage 1.0 or more?
Yes
Repair or replace for a short to ground in the wiring harness.
No
Go to the next step.
2
INSPECT FRONT SEAT WARMER UNIT
•  Inspect the front seat warmer unit.
•  Is the front seat warmer unit normal?
Yes
Go to the next step.
No
Replace the front seat back pad.
(See FRONT SEAT CUSHION TRIM REMOVAL/INSTALLATION.)
3
INSPECT INDICATOR UNIT
•  Inspect the indicator unit.
•  Is the indicator unit normal?
Yes
Replace the front seat warmer control unit.
(See FRONT SEAT WARMER CONTROL UNIT REMOVAL/INSTALLATION.)
No
Replace the indicator unit.
(See INDICATOR UNIT REMOVAL/INSTALLATION.)