2001 was a common year for heating elements to go bad, in fact there was a service bulletin published for it. Since it comes on, and immediately shuts down, it is an indication that there is either too much current flow, or too much resistance to current flow. You would need to check resistance of each individual element. Not necessarily all are bad, it may just be one. If it is a base deville, it has one element in each cushion(bottom/back). If it is DHS/DTS it has four(back/bottom/thigh(x2)).
Here is a guide to check for power and to check the relays and see if power is coming out of the heater control module under the driver's seat.
(Below is the wiring diagrams)
Here is the bulletin.
#01-08-50-001C: Front/Rear Heated Seat Inoperative/Cold (Install Seat Heat Element) - (Jul 1, 2011)
Front/Rear Heated Seat Inoperative/Cold (Install Seat Heat Element)
2000 2003 Cadillac DeVille (All Models) with RPO KA1
This bulletin is being revised to update the model year information. Please discard Corporate Bulletin Number?01-08-50-001B (Section 08 Body and Accessories)
Some customers may comment that the front/rear seat assembly heat function is not operating properly. The front/rear seat back and seat cushion remain cold when either the HEAT/OFF switch or the BACK ONLY switch is activated.
This condition may be due to a non-functioning heat element in the front/rear heated seat back/cushion trim cover.
The heated seat system consists of four heated seats, two in the front and two in the rear. On the DHS and DTS models, each heated seat consists of four heat elements, one in the seat back and three in the seat cushion. On the DeVille model, each heated seat consists of two heat elements, one in the seat back and one in the seat cushion.
My money is on a bad seat control module FYI.
Check out the diagrams (Below)
Please let us know what you find. We are interested to see what it is.
Images (Click to enlarge)
Monday, December 4th, 2017 AT 2:09 PM