Putting heated seats in a Jeep from another, similar year Jeep sounds simple, right?  Get a load of how the stock 2001 Grand Cherokee seats work.

You press the button on the dash, which grounds the switch out through a resistor.  If you want it off: 55ohms, if you want high: 365ohms, if you want low: 1430ohms.  Fun, huh?  Oh... but it doesn't end there.

Say, you select the high setting by pressing the high button in the dash, which then grounds the switch through a 365 ohm resistor.  Well, the other end of that wire goes to the Body Control Module, the same computer that controls power windows, interior dome light delay, interior dome light shut off and other fun things.  From the BCM, a multiplexed signal (think like a tiny pygmy who knows Morse code- sending a specific signal down the wire saying you want "high"- other things get different Morse code type signals, but on the same wire) is sent through the PCI bus to the Heated Seat Module, or Memory Heated Seat module, which is a computer as well, and it "looks" to see if the heated seat elements are at 105 degrees or more.  If they are under 105 (Fahrenheit), then the HSM, or MHSM "tells" (more pygmy Morse code) the BCM that the end user (you) can have the "high butt heating" that you desired.

With me so far?

The idea was simple: The lower back support in the 98 XJ seats suck.  Whether that was from the factory or because these particular seats had 200+ thousand miles on them, I don't know, and don't really care.  When I can nab a set of 2001 Grand Cherokee Leather Power Heated Seats (power lumbar support) for 350 dollars shipped to my door (ok, the office doors, but still) why would I care about the stock one?

I wanted the full power, for the long trips this Jeep is going to see.  On a recent trip to Vegas for a Jeepspeed race, I got there with my back hurting thanks to the lack of support.  The way to get power lumbar and other things was to go leather, which I could have done without, but for the price, why not?  And then, I figure while I'm putting in new seats, why not put heated ones in?  For another 25 bucks, it sounded like a good idea at the time.

Now, I find out all of this computer hunky-dory-ness.  Which, in and of itself isn't a big deal.  The Body Control Module for the 01 Grand is like 50 bucks off ebay... so that won't break the bank.  Finding the plugs for it is another story though.  Oh, and say I do find the plugs, get the thing wired up (using either the factory switches from a Grand, or my own bastardized versions that ground through resistors).  Then, from what I gather, I have to hook the BCM to a DRBIII (expensive Chrysler diagnostic machine) and trick the BCM into thinking it is still in an 01 Grand.  I don't even know if that part is possible, truth be told.  But it would be neat to have the interior lights shut themselves off after leaving the door open for so long, or maybe swap in a WJ overhead console which tells me way more things than my XJ console does.

OH, and the simple solution of just adding aftermarket heat pads?   If I really wanted the heat, which I don't.  At least not enough to dump money on questionable aftermarket parts (I'm not spending more money to get it, if the BCM thing falls through).  Oh, the aftermarket pads, when installed in the factory heated seats means I get less actual heat coming through the seat than I would if I'd saved the 25 bucks and gotten the "regular seats".

But look at the rear seats side by side.  Sure does look nice, doesn't it?  Front seats offer similar gains.