Seat System - Seating: Overview Ford Focus II рестайлинг

Normal Operation

Each front seat has a heated seat relay mounted to the seat track. There are 2 voltage supplies to the heated seat relay. When the ignition switch is ON, voltage is supplied from the smart junction box (SJB) to each heated seat relay coil through heated seat relay enable circuit CHS25 (YE). When the engine is running and the driver or passenger heated seat button is pressed to on, ground is supplied to the opposite side of the driver or passenger relay coil by HVAC module driver heated seat relay drive circuit CHS29 (WH/BU) or passenger heated seat relay drive circuit CHS30 (GY/YE) to energize the affected relay. The switch indicators can only be illuminated with the engine running. The relay contact closes to supply battery voltage from SJB circuit CHS02 (YE/BU) to the driver heater mat circuit CHS11 (VT/GN) or passenger heater mat circuit CHS07 (GY/BU). The driver heater mats are connected to ground circuit GD906 (BK/GY) and the passenger heater mats are connected to ground circuit GD905 (BK/GN) completing the electrical circuits to heat the seats.

This pinpoint test is intended to diagnose the following

1. Fuse(s)
2. Wiring, terminals or connectors
3. HVAC module

Scheme 1

Scheme 2

Scheme 3

1. A1 CHECK THE HEATED SEAT INDICATORS Start the engine. Verify the HVAC module operates by checking other climate control system features. Press both heated seat switches to on. Does the HVAC module operate and do both heated seat switch indicators illuminate? YES : Go to A2 . NO : REFER to «CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS»(ref-357136) article to diagnose any climate control system concerns. Otherwise, INSTALL a new HVAC module. REFER to «CLIMATE CONTROL»(ref-357171) article. TEST the system for normal operation.
2. A2 CHECK THE HVAC MODULE FOR HEATED SEAT DTCs Enter the following diagnostic mode on the diagnostic tool: Self Test/ HVAC Module/ Retrieve DTCs Are any DTCs retrieved? YES : For any HVAC heated seat DTCs, REFER to «HVAC Module DTC Chart»(ref-357191-S42749453102010030800000) . NO : Go to A3 .
3. A3 CHECK THE HEATED SEAT RELAY CIRCUITS CHS02 (YE/BU) AND CHS25 (YE) FOR VOLTAGE Key in OFF position. Depower the supplemental restraint system (SRS). Refer to Supplemental Restraint System (SRS) Depowering and Repowering in the General Procedures portion of «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article. Disconnect: Driver Seat Side Air Bag C367 or Passenger Seat Side Air Bag C337 Disconnect: Driver Safety Belt Buckle and Pretensioner C3201 or Passenger Safety Belt Buckle and Pretensioner C3202 Disconnect: Driver Heated Seat Relay C3250 or Passenger Heated Seat Relay C3251 WARNING: Make sure no one is in the vehicle and there is nothing blocking or placed in front of any air bag module when the battery is connected. Failure to follow these instructions may result in serious personal injury in the event of an accidental deployment. Connect the battery ground cable. Refer to «BATTERY, MOUNTING AND CABLES»(ref-357167) article. Key in ON position. Measure the voltage between driver heated seat relay C3250-30 circuit CHS02 (YE/BU), harness side and ground or passenger heated seat relay C3251-30 circuit CHS02 (YE/BU), harness side and ground; and between driver heated seat relay C3250-86 circuit CHS25 (YE), harness side and ground or passenger heated seat relay C3251-86 circuit CHS25 (YE) harness side and ground. Are the voltages greater than 10 volts? YES : INSTALL a new HVAC module. REFER to «CLIMATE CONTROL»(ref-357171) article. TEST the system for normal operation. NO : VERIFY SJB fuses 18 (20A) and 43 (10A) are OK. If SJB fuse 18 (20A) is open, go to A4 . If OK, REPAIR the affected open circuit CHS02 (YE/BU) or CHS25 (YE). TEST the system for normal operation. DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle and pretensioner C3201 or passenger seat safety belt buckle and pretensioner C3202 and driver seat side air bag C367 or passenger seat side air bag C337. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article.
4. A4 CHECK HEATER CIRCUITS CHS11 (VT/GN) AND CHS07 (GY/BU) FOR A SHORT TO GROUND Key in OFF position. Disconnect: Driver Cushion Heater Mat C364 and Passenger Cushion Heater Mat C334 Measure the resistance between driver heated seat relay C3250-87 circuit CHS11 (VT/GN), harness side and ground; and between passenger heated seat relay C3251-87 circuit CHS07 (GY/BU), harness side and ground. Are the resistances greater than 10,000 ohms? YES : Go to A5 . NO : REPAIR the affected circuit. TEST the system for normal operation. DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle and pretensioner C3201 or passenger seat safety belt buckle and pretensioner C3202 and driver seat side air bag C367 or passenger seat side air bag C337. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article.
5. A5 CHECK THE HEATER MATS FOR A SHORT TO GROUND Disconnect: Driver and Passenger Backrest Heater Mat Electrical Connectors Measure the resistance between driver cushion heater mat C364 pin 1, component side and ground; and between driver cushion heater mat C364 pin 2, component side and ground; and between passenger cushion heater mat C334 pin 1, component side and ground; and between passenger cushion heater mat C334 pin 1, component side and ground. Measure the resistance between driver backrest heater mat connector pin 1, component side and ground; and between driver backrest heater mat C364 pin 2, component side and ground; and between passenger backrest heater mat C334 pin 1, component side and ground; and between passenger backrest heater mat C334 pin 1, component side and ground. Are the resistances greater than 10,000 ohms? YES : CHECK the heated seat wiring, heater mats and connector pins for damage and REPAIR as needed. TEST the system for normal operation. DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle and pretensioner C3201 or passenger seat safety belt buckle and pretensioner C3202 and driver seat side air bag C367 or passenger seat side air bag C337. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article. NO : INSTALL a new cushion or backrest heater mat. TEST the system for normal operation. DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle and pretensioner C3201 or passenger seat safety belt buckle and pretensioner C3202 and driver seat side air bag C367 or passenger seat side air bag C337. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article.

The driver seat has a heated seat relay mounted to the seat track. There are 2 voltage supplies to the heated seat relay. When the ignition switch is ON, voltage is supplied from the smart junction box (SJB) to the heated seat relay coil through heated seat relay enable circuit CHS25 (YE). When the engine is running and the heated seat switch is pressed on, ground is supplied to the opposite side of the relay coil by HVAC module driver heated seat relay drive circuit CHS29 (WH/BU) to energize the relay. The switch indicator can only be illuminated with the engine running. The relay contact closes to supply battery voltage from circuit CHS02 (YE/BU) to the driver heater mat circuit CHS11 (VT/GN). The driver heater mats are connected to ground circuit GD906 (BK/GY) completing the electrical circuit to heat the seat.

1. DTC B12AB Drivers Heated Seat Relay Drive Circuit Shorted to Battery Voltage - If the driver heated seat relay drive circuit CHS02 (YE/BU) is shorted to voltage and the HVAC module attempts to activate the driver heated seat relay, the DTC will set and the seat will fail to heat.
2. DTC B12AC Drivers Heated Seat Relay Drive Circuit Open or Shorted to Ground - If the driver heated seat relay drive circuit CHS02 (YE/BU) is open or shorted to ground and the HVAC module attempts to activate the driver heated seat relay, the DTC will set and the seat will fail to heat (circuit open) or may be on at all times (circuit shorted to ground) until the ignition key is OFF.

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Heated seat relay
3. Backrest or cushion heater mat
4. HVAC module

Scheme 4

Scheme 5

Scheme 6

Scheme 7

Scheme 8

Scheme 9

Scheme 10

1. B1 CHECK THE DRIVER HEATED SEAT INDICATOR OPERATION Start the engine. Operate the driver heated seat switch. Does the HVAC module operate and does the driver heated seat switch indicator illuminate? YES : Go to B2 . NO : REFER to «CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS»(ref-357136) article to diagnose any climate control system concerns. Otherwise, INSTALL a new HVAC module. REFER to «CLIMATE CONTROL»(ref-357171) article. TEST the system for normal operation.
2. B2 CHECK THE HEATED SEAT OPERATION Operate the system and determine if the seat is heating. Does the seat heat? YES : Key OFF. Go to B12 . NO : Go to B3 .
3. B3 CHECK THE HVAC MODULE FOR HEATED SEAT DTCs Enter the following diagnostic mode on the diagnostic tool: Self Test/ HVAC Module/ Retrieve DTCs Is DTC B12AB or B12AC retrieved? YES : If DTC B12AB is present, go to B4 . If DTC B12AC is present, go to B5 . For any other HVAC module DTC, REFER to «CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS»(ref-357136) article to diagnose the fault. NO : Go to B7 .
4. B4 CHECK CONTROL CIRCUIT CHS29 (WH/BU) FOR A SHORT TO VOLTAGE Key in OFF position. Depower the supplemental restraint system (SRS). Refer to Supplemental Restraint System (SRS) Depowering and Repowering in the General Procedures portion of «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article. Disconnect: Driver Seat Side Air Bag C367 Disconnect: Driver Safety Belt Buckle and Pretensioner C3201 Disconnect: Driver Heated Seat Relay C3250 Disconnect: HVAC Module C2357a WARNING: Make sure no one is in the vehicle and there is nothing blocking or placed in front of any air bag module when the battery is connected. Failure to follow these instructions may result in serious personal injury in the event of an accidental deployment. Connect the battery ground cable. Refer to «BATTERY, MOUNTING AND CABLES»(ref-357167) article. Key in ON position. Measure the voltage between driver heated seat relay C3250-85 circuit CHS29 (WH/BU), harness side and ground. Is any voltage present? YES : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle and pretensioner C3201 and driver seat side air bag C367. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article. NO : INSTALL a new driver heated seat relay. RECONNECT all connectors and REPEAT the self-test. If the DTC is retrieved again, INSTALL a new HVAC module. CLEAR the DTCs. REPEAT the self-test. DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle and pretensioner C3201 and driver seat side air bag C367. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article.
5. B5 CHECK CIRCUIT CHS29 (WH/BU) FOR A SHORT TO GROUND Key in OFF position. Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering in the General Procedures portion of «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article. Disconnect: Driver Seat Side Air Bag C367 Disconnect: Driver Safety Belt Buckle and Pretensioner C3201 Disconnect: Driver Heated Seat Relay C3250 Disconnect: HVAC Module C2357a Measure the resistance between driver heated seat relay C3250-85 circuit CHS29 (WH/BU), harness side and ground. Is the resistance greater than 10,000 ohms? YES : Go to B6 . NO : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. CONNECT driver seat safety belt buckle and pretensioner C3201 and driver seat side air bag C367. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article.
6. B6 CHECK CIRCUITS CHS29 (WH/BU) AND CHS02 (YE/BU) FOR AN OPEN Measure the resistance between driver heated seat relay C3250-85 circuit CHS29 (WH/BU), harness side and HVAC module C2357a-1 circuit CHS02 (YE/BU), harness side. Is the resistance less than 5 ohms? YES : CHECK the relay and HVAC module connectors and pins for damage. REPAIR as necessary. RECONNECT the connectors. REPEAT the self-test. If the DTC is retrieved again, INSTALL a new HVAC module. REFER to «CLIMATE CONTROL»(ref-357171) article. CLEAR the DTCs. REPEAT the self-test. CONNECT driver seat safety belt buckle and pretensioner C3201 and driver seat side air bag C367. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article. NO : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. CONNECT driver seat safety belt buckle and pretensioner C3201 and driver seat side air bag C367. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article.
7. B7 CHECK CIRCUIT CHS11 (VT/GN) FOR VOLTAGE Key in OFF position. Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering in the General Procedures portion of «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article. Disconnect: Driver Seat Side Air Bag C367 Disconnect: Driver Safety Belt Buckle and Pretensioner C3201 Disconnect: Driver Cushion Heater Mat C364 WARNING: Make sure no one is in the vehicle and there is nothing blocking or placed in front of any air bag module when the battery is connected. Failure to follow these instructions may result in serious personal injury in the event of an accidental deployment. Connect the battery ground cable. Refer to «BATTERY, MOUNTING AND CABLES»(ref-357167) article. Start the engine. Press the driver heated seat switch on and measure the voltage between driver seat cushion heater mat C364-1 circuit CHS11 (VT/GN), harness side and ground. Is the voltage greater than 10 volts? YES : Go to B11 . NO : Go to B8 .
8. B8 SWAP HEATED SEAT RELAYS AND CHECK CIRCUIT CHS11 (VT/GN) FOR VOLTAGE Key in OFF position. Disconnect: Driver Heated Seat Relay C3250 Disconnect: Passenger Heated Seat Relay C3251 Swap relays by installing the passenger heated seat relay into the driver heated seat relay connector. Start the engine. Press the driver heated seat switch on and measure the voltage between driver seat heater mat C364-1 circuit CHS11 (VT/GN), harness side and ground. Is the voltage greater than 10 volts? YES : INSTALL a new heated seat relay. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle and pretensioner C3201 and driver seat side air bag C367. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article. NO : DISCONNECT the test relay and Go to B9 .
9. B9 CHECK DRIVER HEATED SEAT RELAY CIRCUITS CHS02 (YE/BU) AND CHS25 (YE) FOR VOLTAGE Measure the voltage between driver heated seat relay C3250-30 circuit CHS02 (YE/BU), harness side and ground; and between driver heated seat relay C3250-86 circuit CHS25 (YE), harness side and ground. Are the voltages greater than 10 volts? YES : Go to B10 . NO : VERIFY SJB fuses 18 (20A) and 43 (10A) are OK. If OK, REPAIR the affected circuit CHS02 (YE/BU) or CHS25 (YE). CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle and pretensioner C3201 and driver seat side air bag C367. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article.
10. B10 CHECK CIRCUIT CHS11 (VT/GN) FOR AN OPEN Key in OFF position. Measure the resistance between driver heated seat relay C3250-87 circuit CHS11 (VT/GN), harness side and driver cushion heater mat C364-1 circuit CHS11 (VT/GN), harness side. Is the resistance less than 5 ohms? YES : INSTALL a new HVAC module. REFER to «CLIMATE CONTROL»(ref-357171) article. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle and pretensioner C3201 and driver seat side air bag C367. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article. NO : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle and pretensioner C3201 and driver seat side air bag C367. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article.
11. B11 CHECK HEATER MAT GROUND CIRCUIT GD906 (BK/GY) FOR AN OPEN Key in OFF position. Measure the resistance between driver cushion heater mat C364-2 circuit GD906 (BK/GY), harness side and ground. Is the resistance less than 5 ohms? YES : Go to B12 . NO : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle and pretensioner C3201 and driver seat side air bag C367. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article.
12. B12 CHECK HEATER MAT RESISTANCE Disconnect: Driver Cushion Heater Mat C364 Measure the resistance between driver cushion heater C364 pins 1 and 2, component side. Is the resistance between 2.5 and 5 ohms? YES : The system checks OK at this time, the concern may be intermittent. CHECK for loose or damaged connector pins and wiring damage. REPAIR as needed. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle and pretensioner C3201 and driver seat side air bag C367. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article. NO : Go to B13 .
13. B13 CHECK THE BACKREST HEATER MAT RESISTANCE Disconnect: Driver Backrest Heater Mat Electrical Connector Measure the resistance between driver backrest heater mat electrical connector pins 1 and 2, component side. Is the resistance between 1.0 and 2.5 ohms? YES : INSTALL a new cushion heater mat. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle and pretensioner C3201 and driver seat side air bag C367. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article. NO : INSTALL a new backrest heater mat. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle and pretensioner C3201 and driver seat side air bag C367. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article.

The passenger seat has a heated seat relay mounted to the seat track. There are 2 voltage supplies to the heated seat relay. When the ignition switch is ON, voltage is supplied from the smart junction box (SJB) to the heated seat relay coil through heated seat relay enable circuit CHS25 (YE). When the engine is running and the heated seat switch button is pressed on, ground is supplied to the opposite side of the relay coil by HVAC module passenger heated seat relay drive circuit CHS30 (GY/YE) to energize the relay. The switch indicator can only be illuminated with the engine running. The relay contact closes to supply battery voltage from circuit CHS02 (YE/BU) to the passenger heater mat circuit CHS07 (GY/BU). The passenger heater mats are connected to ground circuit GD905 (BK/BN) completing the electrical circuit to heat the seat.

1. DTC B12AD Passenger Heated Seat Relay Drive Circuit Shorted to Battery Voltage - If the passenger heated seat relay drive circuit CHS07 (GY/BU) is shorted to voltage and the HVAC module attempts to activate the passenger heated seat relay, the DTC will set and the seat will fail to heat.
2. DTC B12AE Passenger Heated Seat Relay Drive Circuit Open or Shorted to Ground - If the passenger heated seat relay drive circuit CHS07 (GY/BU) is open or shorted to ground and the HVAC module attempts to activate the passenger heated seat relay, the DTC will set and the seat will fail to heat (circuit open) or may be on at all times (circuit shorted to ground) until the ignition key is OFF.

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Heated seat relay
3. Backrest or cushion heater mat
4. HVAC module

Scheme 11

1. C1 CHECK THE PASSENGER HEATED SEAT INDICATOR OPERATION Start the engine. Operate the passenger heated seat switch. Does the HVAC module operate and does the passenger heated seat switch indicator illuminate? YES : Go to C2 . NO : REFER to «CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS»(ref-357136) article to diagnose any climate control system concerns. Otherwise, INSTALL a new HVAC module. REFER to «CLIMATE CONTROL»(ref-357171) article. TEST the system for normal operation.
2. C2 CHECK THE HEATED SEAT OPERATION Operate the system and determine if the seat is heating. Does the seat heat? YES : Key OFF. Go to C12 . NO : Go to C3 .
3. C3 CHECK THE HVAC MODULE FOR HEATED SEAT DTCs Enter the following diagnostic mode on the diagnostic tool: Self Test/ HVAC Module/ Retrieve DTCs Is DTC B12AD or B12AE retrieved? YES : If DTC B12AD is present, go to C4 . If DTC B12AE is present, go to C5 . For any other HVAC module DTC, REFER to «CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS»(ref-357136) article to diagnose the fault. NO : Go to C7 .
4. C4 CHECK CONTROL CIRCUIT CHS30 (GY/YE) FOR A SHORT TO VOLTAGE Key in OFF position. Depower the supplemental restraint system (SRS). Refer to Supplemental Restraint System (SRS) Depowering and Repowering in the General Procedures portion of «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article. Disconnect: Passenger Seat Side Air Bag C337 Disconnect: Passenger Safety Belt Buckle and Pretensioner C3202 Disconnect: Passenger Heated Seat Relay C3251 Disconnect: HVAC Module C2357a WARNING: Make sure no one is in the vehicle and there is nothing blocking or placed in front of any air bag module when the battery is connected. Failure to follow these instructions may result in serious personal injury in the event of an accidental deployment. Connect the battery ground cable. Refer to «BATTERY, MOUNTING AND CABLES»(ref-357167) article. Key in ON position. Measure the voltage between passenger heated seat relay C3251-85 circuit CHS30 (GY/YE), harness side and ground. Is any voltage present? YES : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. DISCONNECT the battery ground cable. CONNECT passenger seat safety belt buckle and pretensioner C3202 and passenger seat side air bag C337. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article. NO : INSTALL a new passenger heated seat relay. RECONNECT all connectors and REPEAT the self-test. If the DTC is retrieved again, INSTALL a new HVAC module. CLEAR the DTCs. REPEAT the self-test. DISCONNECT the battery ground cable. CONNECT passenger seat safety belt buckle and pretensioner C3202 and passenger seat side air bag C337. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article.
5. C5 CHECK CIRCUIT CHS30 (GY/YE) FOR A SHORT TO GROUND Key in OFF position. Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering in the General Procedures portion of «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article. Disconnect: Passenger Seat Side Air Bag C337 Disconnect: Passenger Safety Belt Buckle and Pretensioner C3202 Disconnect: Passenger Heated Seat Relay C3251 Disconnect: HVAC Module C2357a Measure the resistance between passenger heated seat relay C3251-85 circuit CHS30 (GY/YE), harness side and ground. Is the resistance greater than 10,000 ohms? YES : Go to C6 . NO : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. CONNECT passenger seat safety belt buckle and pretensioner C3202 and passenger seat side air bag C337. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article.
6. C6 CHECK CIRCUITS CHS30 (GY/YE) AND CHS07 (GY/BU) FOR AN OPEN Measure the resistance between passenger heated seat relay C3251-85 circuit CHS30 (GY/YE), harness side and HVAC module C2357a-5 circuit CHS07 (GY/BU), harness side. Is the resistance less than 5 ohms? YES : CHECK the relay and HVAC module connectors and pins for damage. REPAIR as necessary. RECONNECT the connectors. REPEAT the self-test. If the DTC is retrieved again, INSTALL a new HVAC module. REFER to «CLIMATE CONTROL»(ref-357171) article. CLEAR the DTCs. REPEAT the self-test. CONNECT passenger seat safety belt buckle and pretensioner C3202 and passenger seat side air bag C337. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article. NO : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. CONNECT passenger seat safety belt buckle and pretensioner C3202 and passenger seat side air bag C337. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article.
7. C7 CHECK CIRCUIT CHS07 (GY/BU) FOR VOLTAGE Key in OFF position. Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering in the General Procedures portion of «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article. Disconnect: Passenger Seat Side Air Bag C337 Disconnect: Passenger Safety Belt Buckle and Pretensioner C3202 Disconnect: Passenger Cushion Heater Mat C334 WARNING: Make sure no one is in the vehicle and there is nothing blocking or placed in front of any air bag module when the battery is connected. Failure to follow these instructions may result in serious personal injury in the event of an accidental deployment. Connect the battery ground cable. Refer to «BATTERY, MOUNTING AND CABLES»(ref-357167) article. Start the engine. Press the passenger heated seat switch on and measure the voltage between passenger seat heater mat C334-1 circuit CHS07 (GY/BU), harness side and ground. Is the voltage greater than 10 volts? YES : Go to C11 . NO : Go to C8 .
8. C8 SWAP HEATED SEAT RELAYS AND CHECK CIRCUIT CHS07 (GY/BU) FOR VOLTAGE Key in OFF position. Disconnect: Passenger Heated Seat Relay C3251 Disconnect: Driver Heated Seat Relay C3250 Swap relays by installing the driver heated seat relay into the passenger heated seat relay connector. Start the engine. Press the passenger heated seat switch on and measure the voltage between passenger seat heater mat C334-1 circuit CHS07 (GY/BU), harness side and ground. Is the voltage greater than 10 volts? YES : INSTALL a new heated seat relay. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. DISCONNECT the battery ground cable. CONNECT passenger seat safety belt buckle and pretensioner C3202 and passenger seat side air bag C337. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article. NO : DISCONNECT the test relay and Go to C9 .
9. C9 CHECK THE PASSENGER HEATED SEAT RELAY CIRCUITS CHS02 (YE/BU) AND CHS25 (YE) FOR VOLTAGE Measure the voltage between passenger heated seat relay C3251-30 circuit CHS02 (YE/BU), harness side and ground; and between passenger heated seat relay C3251-86 circuit CHS25 (YE), harness side and ground. Are the voltages greater than 10 volts? YES : Go to C10 . NO : VERIFY SJB fuses 18 (20A) and 43 (10A) are OK. If OK, REPAIR the affected circuit CHS02 (YE/BU) or CHS25 (YE). CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. DISCONNECT the battery ground cable. CONNECT passenger seat safety belt buckle and pretensioner C3202 and passenger seat side air bag C337. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article.
10. C10 CHECK CIRCUIT CHS07 (GY/BU) FOR AN OPEN Key in OFF position. Measure the resistance between passenger heated seat relay C3251-87 circuit CHS07 (GY/BU), harness side and passenger cushion heater mat C334-1 circuit CHS07 (GY/BU), harness side. Is the resistance less than 5 ohms? YES : INSTALL a new HVAC module. REFER to «CLIMATE CONTROL»(ref-357171) article. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. DISCONNECT the battery ground cable. CONNECT passenger seat safety belt buckle and pretensioner C3202 and passenger seat side air bag C337. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article. NO : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. DISCONNECT the battery ground cable. CONNECT passenger seat safety belt buckle and pretensioner C3202 and passenger seat side air bag C337. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article.
11. C11 CHECK HEATER MAT GROUND CIRCUIT GD905 (BK/GN) FOR AN OPEN Key in OFF position. Measure the resistance between passenger seat heater mat C334-2 circuit GD905 (BK/GN), harness side and ground. Is the resistance less than 5 ohms? YES : Go to C12 . NO : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. DISCONNECT the battery ground cable. CONNECT passenger seat safety belt buckle and pretensioner C3202 and passenger seat side air bag C337. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article.
12. C12 CHECK HEATER MAT RESISTANCE Disconnect: Passenger Cushion Heater Mat C334 Measure the resistance between passenger backrest heater mat C334 pins 1 and 2, component side. Is the resistance between 2.5 and 5 ohms? YES : The system checks OK at this time, the concern may be intermittent. CHECK for loose or damaged connector pins and wiring damage. REPAIR as needed. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. DISCONNECT the battery ground cable. CONNECT passenger seat safety belt buckle and pretensioner C3202 and passenger seat side air bag C337. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article. NO : Go to C13 .
13. C13 CHECK THE BACKREST HEATER MAT RESISTANCE Disconnect: Passenger Backrest Heater Mat Electrical Connector Measure the resistance between passenger backrest heater mat electrical connector pins 1 and 2, component side. Is the resistance between 1.0 and 2.5 ohms? YES : INSTALL a new cushion heater mat. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. DISCONNECT the battery ground cable. CONNECT passenger seat safety belt buckle and pretensioner C3202 and passenger seat side air bag C337. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article. NO : INSTALL a new backrest heater mat. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. DISCONNECT the battery ground cable. CONNECT passenger seat safety belt buckle and pretensioner C3202 and passenger seat side air bag C337. REPOWER the SRS. REFER to «SUPPLEMENTAL RESTRAINT SYSTEM»(ref-357180) article.

With the engine running and a heated seat button is pressed ON, the HVAC module supplies a switched ground output to the driver or passenger heated seat relay to energize the relay coil and operate the driver or passenger heated seat. The HVAC module monitors the output circuits CHS29 (WH/BU) (driver) and CHS30 (GY/YE) (passenger) for faults. If circuit CHS29 (WH/BU) (driver) or CHS30 (GY/YE) (passenger) is shorted to ground, HVAC DTC B12AC (driver seat) or B12AE (passenger seat) will set. If a short to ground condition exists on the output circuit, the seat may continue to heat after being switched off. If DTC B12AC or B12AE is set and the affected seat is inoperative, go to Pinpoint Test B (driver seat) or Go to Pinpoint Test C (passenger seat) to diagnose the fault.

1. DTC B12AC Drivers Heated Seat Relay Drive Circuit Open or Shorted to Ground - If the driver heated seat relay drive circuit CHS02 (YE/BU) is open or shorted to ground and the HVAC module attempts to activate the driver heated seat relay, the DTC will set and the seat will fail to heat (circuit open) or may be on at all times (circuit shorted to ground) until the ignition key is OFF.
2. DTC B12AE Passenger Heated Seat Relay Drive Circuit Open or Shorted to Ground - If the passenger heated seat relay drive circuit CHS07 (GY/BU) is open or shorted to ground and the HVAC module attempts to activate the passenger heated seat relay, the DTC will set and the seat will fail to heat (circuit open) or may be on at all times (circuit shorted to ground) until the ignition key is OFF.

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Heated seat relay
3. Backrest or cushion heater mat
4. HVAC module