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Home >> Ford >> 2003 >> Expedition 2WD V8-5.4L SOHC VIN L >> Repair and Diagnosis >> Body and Frame >> Seats >> Seat Temperature Control Module >> Technical Service Bulletins >> Customer Interest >> Interior - Climate Controlled Seats Operate Erratically >> Service Procedure >> Diagnostics B
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Diagnostics B

DIAGNOSTICS "B" - CLIMATE CONTROLLED SEAT SHUTS OFF AFTER MORE THAN 10 SECONDS, BUT LESS THAN 40 SECONDS

Turn the engine off and the ignition key to the "ON" position.

Faults that cause the climate controlled seat to shut off between 10 and 40 seconds are usually related to the thermo-electric device (TED) or the thermistor.

If the climate controlled seat shuts down prematurely, there must be a DTC(s) stored in the CCSM. Check the appropriate (driver or passenger side) CCSM for DTC(s).

If a B2731 (Differential Temperature Fault) is set, take note of whether there are additional DTCs in the CCSM. If a B2729 or B2730 is also set in the CCSM, refer to the diagnostics in this section for information on that code. If the B2731 is the only DTC set in the CCSM, the temperature fault could be with either the cushion or the back. Perform the checks outlined in this section for both B2729 and B2730 until the fault is determined.

If a B2729 (Cushion Over-Temperature Detected) is set:

^ Check for a short through the appropriate (driver or passenger side) cushion thermistor. There should be between 1200 (1.2 K) and 3600 (3.6 K) Ohms of resistance at room temperature between Pins 2 and 3 of the climate controlled seat cushion element connector. If resistance is outside this range, replace the appropriate (driver or passenger) cushion TED assembly (the thermistor is a subassembly of the TED).

^ Check for an open in the appropriate (driver or passenger side) cushion TED. There should be between 0.5 and 7.0 Ohms of resistance at room temperature between Pins 4 and 6 of the climate controlled seat cushion element connector. If resistance is greater than 7.0 Ohms, replace the appropriate (driver or passenger) cushion TED assembly.

If a B2730 (Back Over-Temperature Detected) is set:

^ Check for a short through the appropriate (driver or passenger side) backrest thermistor. There should be between 1200 (1.2 K) and 3600 (3.6 K) Ohms of resistance at room temperature between Pins 2 and 3 of the climate controlled seat backrest element connector. If resistance is outside this range, replace the appropriate (driver or passenger) backrest TED assembly (the thermistor is a subassembly of the TED).

^ Check for an open in the appropriate (driver or passenger side) backrest TED. There should be between 0.5 and 7.0 Ohms of resistance at room temperature between Pins 4 and 6 of the climate controlled seat cushion element connector. If resistance is greater than 7.0 Ohms, replace the appropriate (driver or passenger) backrest TED assembly.

NOTE
IF CODES B2729, B2730, AND B2731 ARE STILL PRESENT AFTER PERFORMING THE ABOVE DIAGNOSTICS, BE AWARE THAT SOME 2003-2004 EXPEDITION/NAVIGATOR VEHICLES BUILT PRIOR TO 12/8/2003 AND EQUIPPED WITH CLIMATE CONTROLLED SEATS MAY EXHIBIT PREMATURE SHUTDOWN OF THE SEAT WHEN IT IS IN THE HEAT MODE ON THE SECOND OF SUBSEQUENT HEAT CYCLES. THIS PARTICULAR CONDITION WILL NOT OCCUR DURING THE FIRST HEAT CYCLE, IT WILL OCCUR ON THE SECOND OR THIRD HEAT CYCLE AND IS USUALLY ACCOMPANIED BY OVERHEAT (B2729, B2730) AND/OR DIFFERENTIAL TEMPERATURE (B2731) DTC IN THE CCSM. THIS CONDITION MAY ALSO BE AGGRAVATED OR MORE LIKELY TO OCCUR IF THE OCCUPANT IN THE AFFECTED SEAT FALLS IN THE UPPER PERCENTILE OF THE BODY WEIGHT RANGE. THIS MAY BE DUE TO THE TEMPERATURE RAMP-UP STRATEGY AND TEMPERATURE FAULT DETECTION EMPLOYED BY THE ORIGINAL CCSM. TO SERVICE, REPLACE THE AFFECTED CCSM WITH NEW SERVICE PART NUMBER 2L1Z-14C724-AC.

If a B2792 (Heat Switch Short to Ground) or B2793 (Cool Switch Short to Ground) is set, refer to online Workshop Manual Section 501-10 DTC Index for direction.
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