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Brian, Service Engineer
Category: Car
Satisfied Customers: 1227
Experience:  Master Tech, Bachelor's of Science in Automotive Technology, Ford Factory Trained
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I have a 02 ford explorer. the heated seats dont work

Resolved Question:

I have a 02' ford explorer. the heated seats dont work They are on the same circuit with the moon roof It works so its not a fuse Also memory seat function not working programmed according to the book nothing happens oh the light on the switch does come on can anyone help?
Submitted: 11 years ago.
Category: Car
Expert:  Gene replied 11 years ago.
Both front seats are heated and dont work?
Customer: replied 11 years ago.
yes both seats
Expert:  Brian replied 11 years ago.
I recommend obtaining the wiring diagrams if you haven't already. Be advised that Ford changed the design of the electrical systems on the 2002 Explorers in March of 2002. This means that you need to be aware whether you have an early build or late build vehicle. The exact dates of the changeover depend on the plant at which it was built. The simpler way to tell is this: if the THEFT indicator is a flashing red light in the instrument cluster, it is an early build unit. If there is a flashing red light on TOP of the dashboard, it is a late build vehicle. Another quick note: the early builds have part numbers that start with a '1' and the late build parts all start with '2'. Be careful when ordering parts as they may look similar but function differently.
    In my experience at the Ford Technical Hotline, the most common heated seat fault was an open circuit in the seat bottom cushion heating element. There are 2 elements per seat, one in the bottom cushion and one in the seatback. There is also one heated seat module per seat. Since most of the weight is on the bottom cushion, the bottom
element tends to be the one that fails. Of course,
it would be advisable to make sure the heated seat modules are receiving adequate powers, grounds, and switch signals. Also look for damaged wiring.
     The memory seats are controlled by the DSM-Driver Seat Module. The DSM can store trouble codes that are only available to a Ford specific scan tool (NGS or WDS diagnostic tools). Knowing if the DSM has codes and whether it can communicate at all is helpful. If the module cannot communicate even though it has good power and ground, chances are that the module has failed internally and needs to be replaced. I have seen the DSM fail on other Explorers and would not be surprised if it was causing the memory seats to be inoperative. If the DSM is not at fault it could be possible that a wiring fault or seat position sensor is causing the DSM to not be able to track seat position. Usually a loss of seat position sensor input causes loss of memory seats, but the seats still operate--albeit in a erratic fashion. That is, the seat will only move a bit a time, then the switch must be released and
re-pressed for the seat to inch along again. To check the sensor input would require measuring the voltage at the DSM for the various sensors. The sensors work like a throttle position sensor, there are 3 potentiometers that vary the voltage returned to DSM depending on seat movement. One sensor for fore and aft, one for recline, and one for up/down. The sensors are supplied with a shared 5 volt reference and a shared ground by the DSM. Each sensor also has its own signal wire to provide input to DSM, the signal wires are the only ones that vary their voltage when the seat moves.
Brian, Service Engineer
Category: Car
Satisfied Customers: 1227
Experience: Master Tech, Bachelor's of Science in Automotive Technology, Ford Factory Trained
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