Pinpoint Test L: The Heated Seat Is Inoperative - Driver, Does Not Operate In Low

WARNING: This page is about a different car, the 2010 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.

WARNING: Remove restraint system diagnostic tools from the vehicle prior to road testing. If tools are not removed, the supplemental restraint system (SRS) device may not deploy in a crash. Failure to follow this instruction may result in serious personal injury or death in a crash and possibly violate vehicle safety standards.

NOTE: When installing a new driver seat heater mat (cushion or backrest) or passenger seat backrest heater mat, a new foam pad with the heater mat already attached is required. A new seat heater mat by itself is not available for service for the driver seat.

NOTE: The air bag warning indicator illuminates when the correct Restraints Control Module (RCM) fuse is removed and the ignition switch is ON.

NOTE: The Supplemental Restraint System (SRS) must be fully operational and free of faults before releasing the vehicle to the customer.

NOTE: Verify good battery condition before diagnosing the memory seat system. Poor battery condition may interfere with memory seat operation, even if vehicle starting is possible.

L1 CHECK HEATED SEAT SWITCH INPUT RESISTANCE TO THE HEATED SEAT MODULE
- Key in OFF position.
- Depower the SRS. Refer to GENERAL PROCEDURES article.
- Disconnect: Driver Seat Side Air Bag C315
- Connect: Restraint System Diagnostic Tool 418-133 to Driver Seat Side Air Bag C315
- Disconnect: Heated Seat Module C681
- Measure resistance between heated seat module C681-12, circuit 1255 (WH/RD), harness side and ground while pressing the heated seat switch.
- Is resistance less than 50 ohms when the heated seat switch is pressed and greater than 10,000 ohms when the heated seat switch is not pressed?
1. YES : INSTALL a new heated seat module. REFER to Heated Seat Module - Front Seat . TEST the system for normal operation.
  DISCONNECT the battery ground cable. DISCONNECT the restraint system diagnostic tool from driver seat side air bag C315. CONNECT driver seat side air bag C315. REPOWER the SRS. REFER to GENERAL PROCEDURES article.
2. NO : Go to L2.
L2 CHECK CIRCUIT 1255 (WH/RD) FOR AN OPEN OR SHORT TO GROUND
- Disconnect: Driver Heated Seat Switch C538
- Measure resistance between:
  - driver heated seat switch C538-2, circuit 1255 (WH/RD), harness side and heated seat module C681-12, circuit 1255 (WH/RD), harness side.
  - driver heated seat switch C538-2, circuit 1255 (WH/RD), harness side and ground.
- Is resistance less than 5 ohms between heated seat switch and heated seat module and greater than 10,000 ohms between heated seat switch and ground?
1. YES : Go to L3.
2. NO : REPAIR the circuit. TEST the system for normal operation.
  DISCONNECT the battery ground cable. DISCONNECT the restraint system diagnostic tool from driver seat side air bag C315. CONNECT driver seat side air bag C315. REPOWER the SRS. REFER to GENERAL PROCEDURES article.
L3 CHECK CIRCUIT 1255 (WH/RD) FOR SHORT A TO VOLTAGE
- Key in OFF position.
- Connect the battery ground cable. Refer to BATTERY, MOUNTING AND CABLES article.
- Key in ON position.
- Measure voltage between heated seat module C681-12, circuit 1255 (WH/RD), harness side and ground.
- Is any voltage present?
1. YES : REPAIR the circuit. TEST the system for normal operation.
  DISCONNECT the battery ground cable. DISCONNECT the restraint system diagnostic tool from driver seat side air bag C315. CONNECT driver seat side air bag C315. REPOWER the SRS. REFER to GENERAL PROCEDURES article.
2. NO : INSTALL a new heated seat switch. TEST the system for normal operation.
  DISCONNECT the battery ground cable. DISCONNECT the restraint system diagnostic tool from driver seat side air bag C315. CONNECT driver seat side air bag C315. REPOWER the SRS. REFER to GENERAL PROCEDURES article.