REAR SEAT WARMER CONTROL UNIT INSPECTION

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•  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

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Symptom Trouble Shooting Index

No.

Troubleshooting item

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


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

No.1

Rear seat warmer function is inoperative
DETECTION
Rear seat warmer does not warm seat even though rear seat warmer switch is on
POSSIBLE CAUSE
The power supply is not supplied to filament of rear seat warmer
•  Open circuit in rear seat warmer control unit power supply circuit:
―  Rear seat warmer control unit terminal O and battery positive terminal
―  Rear seat warmer control unit terminal M and battery positive terminal
•  R.SEAT W 20 A fuse malfunction
―  Rear seat warmer control unit terminal O and battery positive terminal
―  Rear seat warmer control unit terminal M and battery positive terminal
•  IG2 30 A fuse malfunction
―  Rear seat warmer control unit terminal K and Ignition positive terminal
•  Poor connect the connector:
―  Left-side rear seat warmer unit connector and rear seat warmer control unit connector
―  Right-side rear seat warmer unit connector and rear seat warmer control unit connector
•  Open circuit in wiring harness between the following terminal:
―  Left-side rear seat warmer unit terminal P and driver-side rear seat warmer unit terminal A
―  Left-side rear seat warmer unit terminal N and passenger-side rear seat warmer unit terminal B
Rear seat warmer control unit not operation
•  Open circuit or short to ground in wiring harness between the following terminal:
―  Rear seat warmer control unit terminal H and body ground
―  Rear seat warmer control unit terminal G and body ground
Rear seat warmer unit cannot control filament on
•  Rear seat warmer unit malfunction
Rear seat warmer filament does not generate heat
•  Left-side rear seat warmer unit (seat cushion side) malfunction
•  Left-side rear seat warmer unit (seat back side) malfunction
•  Right-side rear seat warmer unit (seat cushion side) malfunction
•  Right-side rear seat warmer unit (seat back side) malfunction
Rear seat warmer control unit cannot receive operation signal
•  Rear seat warmer control unit malfunction
•  Open circuit or short to ground in wiring harness between the following terminal:
―  Rear seat warmer control unit terminal I and rear seat warmer switch terminal C

Diagnostic procedure

STEP

INSPECTION

ACTION
1
PERFORM DTC INSPECTION
•  Perform 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 REAR SEAT WARMER SWITCH
•  Select either Low, Mid, or High on the rear seat warmer switch.
•  Does the rear seat warmer switch LED illuminate?
Yes
Go to the next step.
No
Inspect rear seat warmer switch.
(See REAR SEAT WARMER SWITCH INSPECTION.)
3
DETERMINE MALFUNCTIONING SYSTEM
•  Does either the left or right rear seat warmer operate?
Yes
Go to step 9.
No
Go to the next step.
4
INSPECT THE REAR SEAT WARMER CONTROL UNIT POWER SUPPLY FUSE
•  Inspect the R.SEAT W 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:
―  R.SEAT W 20 A fuse and rear seat warmer control unit terminal O
―  R.SEAT W 20 A fuse and rear seat warmer control unit terminal M
5*
DETERMINE IF CAUSE OF MALFUNCTION IS CONTROLLER POWER SUPPLY WIRING HARNESS FOR REAR SEAT WARMER OR OTHER CAUSE
•  Switch the ignition off (LOCK).
•  Disconnect the rear seat warmer control unit connector.
•  Measure the voltage at the following terminal (wiring harness-side):
―  Rear seat warmer control unit terminal O
―  Rear 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.
―  R.SEAT W 20 A fuse and rear seat warmer control unit terminal O
―  R.SEAT W 20 A fuse and rear 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 REAR SEAT WARMER CONTROL UNIT GROUND CIRCUIT
•  Rear seat warmer control unit connector on the side that is not operating is disconnected.
•  Inspect for continuity between the following terminals (wiring harness-side):
―  Rear seat warmer control unit terminal on the side that is not operating H and body ground
―  Rear 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.
―  Rear seat warmer unit terminal H and body ground
―  Rear 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 REAR SEAT WARMER SWITCH SIGNAL
•  Rear seat warmer control unit connector is disconnected.
•  Inspect for continuity between the following terminals (wiring harness-side):
―  Rear seat warmer control unit terminal I and rear seat warmer switch terminal C
•  Is there continuity?
Yes
Go to the next step.
No
•  Inspect the open circuit following.
―  Rear seat warmer control unit terminal I and rear seat warmer switch terminal C
9*
INSPECT REAR SEAT WARMER CONTROL UNIT AND REAR SEAT WARMER UNIT CONNECTOR
•  Disconnect the rear seat warmer control unit and rear seat warmer unit connector on the side not operating.
•  Inspect the rear seat warmer control unit and 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 REAR SEAT WARMER UNIT CIRCUIT
•  Switch the ignition off (LOCK).
•  Disconnect the rear seat warmer control unit connector.
•  Inspect for continuity between the following terminals (wiring harness-side):
―  Left-side rear seat warmer unit terminal P and A
―  Right-side rear seat warmer unit terminal N and B
•  Is there continuity?
Yes
Go to the next step.
No
Replace the rear seat back pad or rear seat cushion pad.
(See REAR SEAT BACK TRIM REMOVAL/INSTALLATION.)
(See REAR SEAT CUSHION TRIM REMOVAL/INSTALLATION.)
11
DETERMINE IF THE MALFUNCTION CAUSE IS REAR SEAT WARMER SWITCH
•  Replace the rear seat warmer switch.
•  Does the rear seat warmer system operate?
Yes
Troubleshooting completed.
No
Replace the rear seat back pad or rear seat cushion pad.
(See REAR SEAT BACK TRIM REMOVAL/INSTALLATION.)
(See REAR SEAT CUSHION TRIM REMOVAL/INSTALLATION.)


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

No.2

Rear seat warmer always operations
DETECTION
Rear seat warmer warms seat even though rear seat warmer switch is off
POSSIBLE CAUSE
•  Short circuit in wiring harness between the following terminal
―   Rear seat warmer control unit terminal N and right-side rear seat warmer unit terminal G
―  Rear seat warmer control unit terminal P and left-side rear seat warmer unit terminal A
•  Right-side rear seat warmer unit malfunction
•  Left-side rear seat warmer unit malfunction
•  Rear seat warmer switch malfunction
•  Rear seat warmer control unit malfunction

Diagnostic procedure

STEP

INSPECTION

ACTION
1*
INSPECT REAR SEAT WARMER UNIT CIRCUIT FOR SHORT TO POWER SUPPLY
•  Disconnect the rear seat warmer control unit connector.
•  Measure the voltage between right-side rear seat warmer unit terminal G and body ground.
•  Measure the voltage between left-side rear seat warmer unit terminal A 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 REAR SEAT WARMER UNIT
•  Inspect the rear seat warmer unit.
•  Is the rear seat warmer unit normal?
Yes
Go to the next step.
No
Replace the rear seat back pad.
(See .REAR SEAT CUSHION TRIM REMOVAL/INSTALLATION)
3
INSPECT REAR SEAT WARMER SWITCH
•  Inspect the rear seat warmer switch.
•  Is the rear seat warmer switch normal?
Yes
Replace the rear seat warmer control unit.
(See REAR SEAT WARMER CONTROL UNIT REMOVAL/INSTALLATION.)
No
Replace the rear seat warmer switch.
(See REAR SEAT WARMER SWITCH REMOVAL/INSTALLATION.)