Cadillac Tech Tips - How to fix it Discussion, Everything you need to know about 1994-1996 DeVille Heated seats. And how to fix them in Item Specific Cadillac Discussion; Firstly I can't take credit for all the work. Much of the info I've compiled from many sources which I ...
After spending a few days completely going though this system to make sure my butt was toasty this winter I figured I should share my findings because lord knows all this info was not in one place.
The FSM manual didnt really explain things and the diagram was lacking some info:
So here is the diagram I came up with.
I tried to be as thorough as possible with wire colors and routing explanations. Especially once you get under the padding and what the connectors are for.
So your seats dont heat? Check the continuity between the connection I pointed to in red arrows (should be the blue wire and green wire) then the connection in purple arrows.
One or both read infinite (no reading)? Then take the seat out of the car. To do this have seat go all the way forward so you can access the T45 bolts hold the rails down. Now you can make the go all the way back and hinge the whole thing forward. You can access the wire connectors easily, there are three clipped to the bottom of the frame. Once the wires are free keep hinging the seat forward untill the front feet can be pulled up from the floor. Take your seat to your favorite work table and try not to scratch the leather.
This next part requires some dexterity. You need to remove the seat covers from the frame. The bottom is held by plastic clips along the frame edge. Once free give it a firm tug over the cushion and you should have all the work space you need. For the backs its not so easy. The bottom seam has a similar clasp/clip setup except the back of the cover is secured to front right where the seat back touches the seat bottom. Be careful not to rip the plastic clip from the leather. Once undone you have to roll the seat cover up the back cushion untill you have room to work. Be mindful of the velcro.
Hopefully the burned wire is obvious at this point. If not look at the green lead for the seat bottom and the brown lead for the back. If you carefully cut the foam away from where these wires enter the pad you should find a burn/break. Check out this guys write up:
He has a Fleetwood. Different setup but the repair to the wire is very clear. I ended up twisting the ends and soldering them. So far so good.
Once you've fixed the breaks check the continuity again. If no go then keep digging for more breaks in the wire.
Once you've determined that your elements are good but you are having a really click happy control module/relay you can check a few things.
1)The temp sensor should read about 12k ohms at 60 degrees F. At least thats what my working one does. If yours has no continuity then you can check its wires going into the pad for breaks. If your resistance is way off you may be out of luck but this is very unlikely.
2)The power going to the switch (brown) and the power out of the switch (pink and blue) should be battery voltage with the engine running. If not then you either have a faulty switch or bad supply.
If you get no clicking from the relay when the switch is on and the engine is running and the thermostat seems ok then the relay may be faulty.
Hope this helps someone. Ill try to answer questions.