SEAT WARMER CONTROL UNIT INSPECTION

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2014 - Mazda6 - Body and Accessories

SEAT WARMER CONTROL UNIT INSPECTION

WARNING:

Handling a side air bag improperly can accidentally operate (deploy) the air bag, which may seriously injure you. Read the service warnings/cautions in the Workshop Manual before handling the front seat (side air bag integrated). (See AIR BAG SYSTEM SERVICE WARNINGS [TWO-STEP DEPLOYMENT CONTROL SYSTEM].) (See AIR BAG SYSTEM SERVICE CAUTIONS [TWO-STEP DEPLOYMENT CONTROL SYSTEM].) (See AIR BAG SYSTEM SERVICE WARNINGS [STANDARD DEPLOYMENT CONTROL SYSTEM].) (See AIR BAG SYSTEM SERVICE CAUTIONS [STANDARD DEPLOYMENT CONTROL SYSTEM].)

If the sliding mechanisms on both sides are not locked after assembling the front seat, the front seat will operate accidentally while the vehicle is driven, which could result in serious injury. After assembling the front seat, shake it up and down and verify that the sliding mechanism on the both sides are locked.

CAUTION:

If the slide lever is operated after the front seat is removed, the left/right slide positions will deviate and the adjuster unit could be damaged after the front seat is installed. After removing a front seat, do not operate the slide lever.

Verify that there are no malfunctions in the forward/back slide of the seat and in the adjuster unit after installing a front seat.

When performing the procedure with a front seat removed from the vehicle, perform the procedure on a clean cloth so as not to damage or soil the seat.

When the passenger's seat is removed, perform the seat weight sensor inspection using the M-MDS after installing the passenger's seat. (See SEAT WEIGHT SENSOR INSPECTION [TWO-STEP DEPLOYMENT CONTROL SYSTEM].)

When the passenger's seat is replaced with a new one, perform the seat weight sensor calibration using the M-MDS. (See SEAT WEIGHT SENSOR CALIBRATION [TWO-STEP DEPLOYMENT CONTROL SYSTEM].)

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

Symptom Trouble Shooting Index


No.	Troubleshooting item	Description
1	Seat warmer function is inoperative (See Inspection Procedure (No.1 Seat Warmer Function Is Inoperative).)	Seat warmer does not warm seat even though seat warmer switch is on
2	Seat warmer operates constantly (See Inspection Procedure (No.2 Seat Warmer Operates Constantly).)	Seat warmer warms seat even though seat warmer switch is off
3	Temperature of the seat warmer cannot be adjusted (See Inspection Procedure (No.3 Temperature Of Seat Warmer Cannot Be Adjusted).)	Seat warmer does not adjust temperature even though seat warmer switch is switched between low and high Seat warmer temperature continues to rise

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


No.1	Seat warmer function is inoperative
DETECTION	Seat warmer does not warm seat even though seat warmer switch is on
POSSIBLE CAUSE	The power supply is not supplied to filament of seat warmer Open circuit in seat warmer control unit power supply circuit: Seat warmer control unit terminal O and battery positive terminal Seat warmer control unit terminal M and battery positive terminal SEAT WARM 20 A fuse malfunction (Blown fuse): Seat warmer control unit terminal O and battery positive terminal Seat warmer control unit terminal M and battery positive terminal Poor connect the connector: Driver-side seat warmer unit connector and seat warmer control unit connector Passenger-side seat warmer unit connector and seat warmer control unit connector Open circuit in wiring harness between the following terminal: Driver-side seat warmer unit terminal P and driver-side seat warmer unit terminal A Passenger-side seat warmer unit terminal N and passenger-side seat warmer unit terminal B Seat warmer control unit not operation Open circuit or short to ground in wiring harness between the following terminal: FBCM terminal 1C and seat warmer control unit terminal K Seat warmer control unit terminal H and body ground Seat warmer control unit terminal G and body ground Seat warmer unit cannot control filament on Seat warmer unit malfunction Seat warmer filament does not generate heat Driver-side seat warmer unit (seat cushion side) malfunction Driver-side seat warmer unit (seat back side) malfunction Passenger-side seat warmer unit (seat cushion side) malfunction Passenger-side seat warmer unit (seat back side) malfunction Seat warmer control unit cannot receive operation signal Seat warmer control unit malfunction Open circuit or short to ground in wiring harness between the following terminal: Seat warmer control unit terminal I and climate control unit terminal 1R (with full-auto air conditioner) Seat warmer control unit terminal I and clock terminal D (with manual air conditioner)

No.1

Seat warmer function is inoperative

DETECTION

Seat warmer does not warm seat even though seat warmer switch is on

POSSIBLE CAUSE

The power supply is not supplied to filament of seat warmer

Open circuit in seat warmer control unit power supply circuit:

Seat warmer control unit terminal O and battery positive terminal

Seat warmer control unit terminal M and battery positive terminal

SEAT WARM 20 A fuse malfunction (Blown fuse):

Seat warmer control unit terminal O and battery positive terminal

Seat warmer control unit terminal M and battery positive terminal

Poor connect the connector:

Driver-side seat warmer unit connector and seat warmer control unit connector

Passenger-side seat warmer unit connector and seat warmer control unit connector

Open circuit in wiring harness between the following terminal:

Driver-side seat warmer unit terminal P and driver-side seat warmer unit terminal A

Passenger-side seat warmer unit terminal N and passenger-side seat warmer unit terminal B

Seat warmer control unit not operation

Open circuit or short to ground in wiring harness between the following terminal:

FBCM terminal 1C and seat warmer control unit terminal K

Seat warmer control unit terminal H and body ground

Seat warmer control unit terminal G and body ground

Seat warmer unit cannot control filament on

Seat warmer unit malfunction

Seat warmer filament does not generate heat

Driver-side seat warmer unit (seat cushion side) malfunction

Driver-side seat warmer unit (seat back side) malfunction

Passenger-side seat warmer unit (seat cushion side) malfunction

Passenger-side seat warmer unit (seat back side) malfunction

Seat warmer control unit cannot receive operation signal

Seat warmer control unit malfunction

Open circuit or short to ground in wiring harness between the following terminal:

Seat warmer control unit terminal I and climate control unit terminal 1R (with full-auto air conditioner)

Seat warmer control unit terminal I and clock terminal D (with manual air conditioner)

Diagnostic procedure


STEP	INSPECTION		ACTION
1	PERFORM DTC INSPECTION Perform instrument cluster and climate control unit DTC inspection. (with full-auto air conditioner) (See DTC INSPECTION [INSTRUMENT CLUSTER].) (See DTC DISPLAY [FULL-AUTO AIR CONDITIONER].) Verify the instrument cluster DTC inspection and clock output check mode. (with manual air conditioner) (See DTC INSPECTION [INSTRUMENT CLUSTER].) (See CLOCK INPUT/OUTPUT CHECK MODE.) Are DTCs and error codes output?	Yes	Perform the diagnosis according to the inspection procedure for each code. (See DTC TABLE [INSTRUMENT CLUSTER].) (See DTC TABLE [FULL-AUTO AIR CONDITIONER].)
1		No	Go to the next step.
2	DETERMINE IF THE MALFUNCTION CAUSE IS THE SEAT WARMER SWITCH Select either Low, Mid, or High on the seat warmer switch. Does the seat warmer switch LED illuminate?	Yes	Go to the next step.
2		No	Inspect the climate control unit or clock. (See CLIMATE CONTROL UNIT INSPECTION [FULL-AUTO AIR CONDITIONER].) (See CLOCK INSPECTION.)
3	DETERMINE MALFUNCTIONING SYSTEM Are the seat warmers on both sides not operating?	Yes	Go to step 9.
3		No	Go to the next step.
4	INSPECT THE SEAT WARMER CONTROL UNIT POWER SUPPLY FUSE Inspect the SEAT WARM 20 A fuse. Is the fuse normal?	Yes	Go to the next step.
4		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 seat warmer control unit terminal O SEAT WARM 20 A fuse and seat warmer control unit terminal M
5*	DETERMINE IF CAUSE OF MALFUNCTION IS CONTROLLER POWER SUPPLY WIRING HARNESS FOR SEAT WARMER OR OTHER CAUSE Switch the ignition off (LOCK). Disconnect the seat warmer control unit connector. Measure the voltage at the following terminal (wiring harness-side): Seat warmer control unit terminal O Seat warmer control unit terminal M Is the voltage B+?	Yes	Go to the next step.
5*		No	Repair or replace the open circuit at the following wiring harness. SEAT WARM 20 A fuse and seat warmer control unit terminal O SEAT WARM 20 A fuse and seat warmer control unit terminal M
6*	VERIFY IF MALFUNCTION CAUSE IS OPEN CIRCUIT IN SEAT WARMER CONTROL UNIT POWER SUPPLY WIRING HARNESS Seat warmer control unit connector are disconnected. Switch the ignition off (LOCK). Measure the voltage at the following terminal (wiring harness-side): Seat warmer control unit terminal K Is the voltage B+?	Yes	Go to the next step.
6*		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 seat warmer control unit terminal K
7*	VERIFY IF MALFUNCTION CAUSE IS SHORT TO GROUND IN SEAT WARMER CONTROL UNIT Seat warmer control unit connector on the side that is not operating is disconnected. Inspect for continuity between the following terminals (wiring harness-side): Seat warmer control unit terminal on the side that is not operating H and body ground 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.
7*		No	Inspect the open circuit following. Seat warmer unit terminal H and body ground 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 SEAT WARMER SWITCH SIGNAL Seat warmer control unit connector is disconnected. Inspect for continuity between the following terminals (wiring harness-side): With full-auto air conditioner Seat warmer control unit terminal I and climate control terminal 1R With manual air conditioner Seat warmer control unit terminal I and clock terminal D Is there continuity?	Yes	Go to the next step.
8*		No	Inspect the open circuit following. Seat warmer control unit terminal I and climate control terminal 1R Seat warmer control unit terminal I and clock terminal D
9*	INSPECT SEAT WARMER CONTROL UNIT AND SEAT WARMER UNIT CONNECTOR Disconnect the seat warmer control unit and seat warmer unit connector on the side not operating. Inspect the 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.
9*		No	Go to the next step.
10*	VERIFY IF MALFUNCTION CAUSE IS OPEN CIRCUIT IN WIRING HARNESS OF SEAT WARMER UNIT CIRCUIT Switch the ignition off (LOCK). Disconnect the seat warmer control unit connector. Inspect for continuity between the following terminals (wiring harness-side): Driver-side seat warmer unit terminal P and A Passenger-side seat warmer unit terminal N and B Is there continuity?	Yes	Go to the next step.
10*		No	Replace the front seat. (See FRONT SEAT REMOVAL/INSTALLATION.)
11	DETERMINE IF THE MALFUNCTION CAUSE IS SEAT WARMER CONTROL UNIT With full-auto air conditioner Replace the climate control unit. (See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER].) With manual air conditioner Replace the clock. (See CLOCK REMOVAL/INSTALLATION.) Does the seat warmer system operate?	Yes	Troubleshooting completed.
11		No	Replace the front seat. (See FRONT SEAT REMOVAL/INSTALLATION.)

Inspection Procedure (No.2 Seat Warmer Operates Constantly)


No.2	Seat warmer operates constantly
DETECTION	Seat warmer warms seat even though seat warmer switch is off
POSSIBLE CAUSE	Seat warmer switch is always on Seat warmer switch malfunction Seat warmer control unit falsely detects seat warmer switch as on Seat warmer control unit malfunction Short circuit in wiring harness between the following terminal: Seat warmer control unit terminal I and climate control unit terminal 1R (with full-auto air conditioner) Seat warmer control unit terminal I and clock terminal D (with manual air conditioner)

No.2

Seat warmer operates constantly

DETECTION

Seat warmer warms seat even though seat warmer switch is off

POSSIBLE CAUSE

Seat warmer switch is always on

Seat warmer switch malfunction

Seat warmer control unit falsely detects seat warmer switch as on

Seat warmer control unit malfunction

Short circuit in wiring harness between the following terminal:

Seat warmer control unit terminal I and climate control unit terminal 1R (with full-auto air conditioner)

Seat warmer control unit terminal I and clock terminal D (with manual air conditioner)

Diagnostic procedure


STEP	INSPECTION		ACTION
1*	DETERMINE IF THE MALFUNCTION CAUSE IS THE SEAT WARMER SWITCH Switch the ignition off (LOCK). With full-auto air conditioner Disconnect the climate control unit connector. With manual air conditioner Disconnect the clock connector. Switch the ignition ON (engine off or on). Is the seat warmer system operating?	Yes	Go to the next step.
1*		No	With full-auto air conditioner Replace the climate control unit. (See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER].) With manual air conditioner Replace the clock. (See CLOCK REMOVAL/INSTALLATION.)
2	DETERMINE IF THE MALFUNCTION CAUSE IS THE SEAT WARMER COTROL UNIT Disconnect the seat warmer control unit connector. Measure the voltage between seat warmer control unit terminal I and body ground. Is the voltage 1.0 or more?	Yes	Repair or replace for a short to ground in the wiring harness.
2		No	Replace the front seat. (See FRONT SEAT REMOVAL/INSTALLATION.)

Inspection Procedure (No.3 Temperature Of Seat Warmer Cannot Be Adjusted)


No.3	Temperature of seat warmer cannot be adjusted
DETECTION	Seat warmer does not adjust temperature even though seat warmer Lo/Mid/Hi switch is switched between low and high Seat warmer temperature continues to rise
POSSIBLE CAUSE	Seat warmer control unit cannot control seat warmer unit Seat warmer control unit malfunction Thermostat (Built-in seat warmer unit) malfunction Short to ground circuit in wiring harness between the following terminal: Seat warmer control unit terminal C and E (Driver-side) Seat warmer control unit terminal D and F (Passenger-side) Seat warmer control unit terminal C and body ground (Driver-side) Seat warmer control unit terminal D and body ground (Passenger-side)

Diagnostic procedure


STEP	INSPECTION		ACTION
1	DETERMINE MALFUNCTIONING SYSTEM Are the seat warmers on both sides not operating?	Yes	Replace the front seat. (See FRONT SEAT REMOVAL/INSTALLATION.)
1		No	Go to the next step.
2*	VERIFY IF MALFUNCTION CAUSE IS OPEN CIRCUIT IN WIRING HARNESS OF SEAT WARMER UNIT CIRCUIT Switch the ignition off (LOCK). Disconnect the seat warmer control unit connector. Inspect for continuity between the following terminals (wiring harness-side): Seat warmer control unit terminal C and E (Driver-side) Seat warmer control unit terminal D and F (Passenger-side) Is there continuity?	Yes	Go to the next step.
2*		No	Replace the front seat. (See FRONT SEAT REMOVAL/INSTALLATION.)
3*	VERIFY IF MALFUNCTION CAUSE IS SHORT CIRCUIT IN WIRING HARNESS OF SEAT WARMER UNIT CIRCUIT Inspect for continuity between the following terminals (wiring harness-side): Seat warmer control unit terminal C and body ground (Driver-side) Seat warmer control unit terminal D and body ground (Passenger-side) Is there continuity?	Yes	Repair or replace for a short to ground in the wiring harness.
3*		No	Replace the front seat. (See FRONT SEAT REMOVAL/INSTALLATION.)

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