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the dreaded heated seat problem


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This is the first time I've actually been involved in the forum but have found this site VERY helpful in the past. I've looked at most all the posts regarding no heat heated seats. Sounds like it is almost always the element. In my 2000 DTS NONE of the elements are working on any of the 4 seats. Bottom or back. Certainly I don't have 8 elements out at the same time. However, when the buttons are pressed for the seat bottom heat or back heat they will each light up and I hear the faint click under the seat but never any heat. So I'm getting power to the module and elements right? I've not tested anything yet because none of them work - not sure where to start? I appreciate any ideas.

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There should be four fuses in the fuse/relay box under the rear seat; could be numbers 6, 16, 31, and 37 and they will be identified as HTDST followed by LF, RF, LR, RR. Ten Amperes.

The calrod elements are the weak link in the system; I have not heard or read about a failed controller. The seat bottom cushion can contain more than one element and in operation, the seat bottom and the seat back are operated in series so you could have only one failed element at each position.

You will need the schematic diagram for your specific year / model to do any troubleshooting with an Ohmeter.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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And there are repair kits that are specific to each model year and each corner of the car. All require some careful cutting of the seats... but all are easy to install in less then an hours worth of time... No need to dread...

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Easin' down the highway in a new Cadillac,

I had a fine fox in front, I had three more in the back

ZZTOP, I'm Bad I'm Nationwide

Greg

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I had similar thing happen to me, the rear seat heaters quit working. Turned out that the electrical connector wasn't connected - the guy who replaced my battery forgot to hook it back up.

I would not regard the fact that they are all not working a coincidence. I'd say there's something common wrong like fuses or something.

2003 Seville STS 43k miles with the Bose Sound, Navigation System, HID Headlamps, and MagneRide

1993 DeVille. Looks great inside and out! 298k miles!

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Here is the TSB for your Deville - Good Luck and have fun

Document ID# 1059134

2000 Cadillac DeVille

--------------------------------------------------------------------------------

Front/Rear Heated Seat Inoperative/Cold (Install Seat Heat Element) #01-08-50-001C - (10/04/2002)

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)

Condition

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.

Cause

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.

FIGURE DHS & DTS Seat Heat Element Locations©

Location #

Part Number

Description

1

25715920

Front Seat Back Cushion Heat Element

2

25715921

Front Seat Cushion Heat Element

3

25715924

Front Seat Cushion (LH Thigh) Heat Element

4

25715925

Front Seat Cushion (RH Thigh) Heat Element

5

25715926

Rear Seat Back Cushion Heat Element

6

25715927

Rear Seat Cushion Heat Element

7

25715928

Rear Seat Cushion (LH Thigh) Heat Element

8

25715929

Rear Seat Cushion (RH Thigh) Heat Element

FIGURE DeVille Seat Heat Element Locations©

Location #

Part Number

Description

1

25740850

Front Seat Back Cushion Heat Element

2

25740851

Front Seat Cushion Heat Element

3

25740853

RH Rear Seat Back Cushion Heat Element

4

25740852

LH Rear Seat Back Cushion Heat Element

5

25740854

LH Rear Seat Cushion Heat Element

6

25740855

RH Rear Seat Cushion Heat Element

Correction

Determine which heat element is not functioning properly by measuring the resistance values of the factory heat elements. Refer to the appropriate diagnostic procedure in this bulletin.

If the resistance values of a factory heat element are NOT within the specified range, install a service heat element between the non-functioning factory heat element and the seat trim cover. Refer to the Service Heat Element Installation Procedure in this bulletin.

DHS/DTS Front Seat Diagnostic Procedure

Adjust the front seat assembly to the maximum up and rearward position in order to access the seat cushion fasteners.

Remove the fasteners (1) retaining the seat cushion to the seat adjuster.

Disconnect the heated seat module harness blue, 8-way connector C2 (2).

Measure the front seat back element resistance between cavities G and H. Does the resistance measure less than 10 ohms?

If yes, go to Step 5.

If no, install a front seat back heat element. Refer to the Service Heat Element Installation Procedure in this bulletin.

Important

If the resistance is measured with the seat still warm, the resistance may vary outside of the specified range since the thermistor resistance varies with temperature.

Measure the front seat back thermistor resistance between cavities E and F. Does the resistance measure between 280 ohms and 300 K ohms?

If yes, go to Step 6.

If no, install a front seat back heat element. Refer to the Service Heat Element Installation Procedure in this bulletin.

Measure the front seat cushion thermistor resistance between cavities C and D. Does the resistance measure between 280 ohms and 300 K ohms?

If yes, go to Step 7.

If no, install a front seat cushion (center) heat element. Refer to the Service Heat Element Installation Procedure in this bulletin.

Measure the front seat cushion element resistance between cavities A and B. Does the resistance measure less than 10 ohms?

If yes, the resistance values of the front seat heat elements are within the specified range. To find the cause of the inoperative/cold heated seat, perform the standard diagnostic procedures in the Service Manual.

If no, go to Step 8 in order to determine which of the three seat cushion heat elements has a resistance value NOT within the specified range.

Remove the front seat assembly from the vehicle. Refer to Seat Replacement in the Seats sub-section of the Service Manual.

Remove the trim cover from the front seat cushion. Refer to Seat Cushion Cover Replacement -- Front in the Seats sub-section of the Service Manual.

Disconnect the green 2-way connectors between the seat cushion center heat element and the seat cushion thigh heat elements.

Measure the LH seat cushion thigh heat element resistance between cavities A and B at the green 2-way connector. Does the resistance measure less than 23 ohms?

If yes, go to Step 12.

If no, install a front seat cushion LH thigh heat element. Refer to the Service Heat Element Installation Procedure in this bulletin.

Measure the RH seat cushion thigh heat element resistance between cavities A and B at the green 2-way connector. Does the resistance measure less than 23 ohms?

If yes, install a front seat cushion (center) heat element. Refer to the Service Heat Element Installation Procedure in this bulletin.

If no, install a front seat cushion RH thigh heat element. Refer to the Service Heat Element Installation Procedure in this bulletin.

DeVille Front Seat Diagnostic Procedure

Adjust the front seat assembly to the maximum up and rearward position in order to access the seat cushion fasteners.

Remove the fasteners (1) retaining the seat cushion to the seat adjuster.

Disconnect the heated seat module harness blue, 8-way connector C2 (2).

Measure the front seat back element resistance between cavities G and H. Does the resistance measure less than 10 ohms?

If yes, go to Step 5.

If no, install a front seat back heat element. Refer to the Service Heat Element Installation Procedure in this bulletin.

Important

If the resistance is measured with the seat still warm, the resistance may vary outside of the specified range since the thermistor resistance varies with temperature.

Measure the front seat back thermistor resistance between cavities E and F. Does the resistance measure between 280 ohms and 300 K ohms?

If yes, go to Step 6.

If no, install a front seat back heat element. Refer to the Service Heat Element Installation Procedure in this bulletin.

Measure the front seat cushion thermistor resistance between cavities C and D. Does the resistance measure between 280 ohms and 300 K ohms?

If yes, go to Step 7.

If no, install a front seat cushion heat element. Refer to the Service Heat Element Installation Procedure in this bulletin.

Measure the front seat cushion element resistance between cavities A and B. Does the resistance measure less than 10 ohms?

If yes, the resistance values of the front seat heat elements are within the specified range. To find the cause of the inoperative/cold heated seat, perform the standard diagnostic procedures in the Service Manual.

If no, install a front seat cushion heat element. Refer to the Service Heat Element Installation Procedure in this bulletin.

DHS/DTS & DeVille Rear Seat Diagnostic Procedure

Remove the rear seat cushion assembly (1) from the vehicle. Refer to Seat Cushion Replacement-Rear in the Seats sub-section of the Service Manual.

Important

If the resistance is measured with the seat still warm, the resistance may vary outside of the specified range since the thermistor resistance varies with temperature.

At the rear seat cushion blue, 8-way connector C320 (2), measure the thermistor resistance.

For the LH rear seat cushion, measure between cavities C and D. Does the resistance measure between 280 ohms and 300 K ohms?

For the RH rear seat cushion, measure between cavities G and H. Does the resistance measure between 280 ohms and 300 K ohms?

If yes, go to Step 3.

If no, install a rear seat cushion (center) heat element. Refer to the Service Heat Element Installation Procedure in this bulletin.

At the rear seat cushion blue, 8-way connector C320 (2), measure the element resistance.

For the LH rear seat cushion, measure between cavities A and B. Does the resistance measure less than 10 ohms?

For the RH rear seat cushion, measure between cavities E and F. Does the resistance measure less than 10 ohms?

If yes, go to Step 8.

If no, for DeVille models ONLY, install a rear seat cushion heat element. Refer to the Service Heat Element Installation Procedure in this bulletin.

If no, for DHS & DTS models ONLY, go to Step 4 in order to determine which of the three rear seat cushion heat elements has a resistance value NOT within the specified range.

For DHS & DTS models ONLY: Remove the trim cover from the rear seat cushion. Refer to Seat Cushion Cover Replacement-Rear in the Seats sub-section of the Service Manual.

For DHS & DTS models ONLY: At the LH/RH rear seat cushion, disconnect the green 2-way connectors between the seat cushion center heat element and the seat cushion thigh heat elements.

For DHS & DTS models ONLY: Measure the LH seat cushion thigh heat element resistance between cavities A and B at the green 2-way connector. Does the resistance measure less than 30 ohms?

If yes, go to Step 7.

If no, install a rear seat cushion LH thigh heat element. Refer to the Service Heat Element Installation Procedure in this bulletin.

For DHS & DTS models ONLY: Measure the RH seat cushion thigh heat element resistance between cavities A and B at the green 2-way connector. Does the resistance measure less than 30 ohms?

If yes, install a rear seat cushion (center) heat element. Refer to the Service Heat Element Installation Procedure in this bulletin.

If no, install a rear seat cushion RH thigh heat element. Refer to the Service Heat Element Installation Procedure in this bulletin.

Remove the rear seat back assembly from the vehicle. Refer to Seat Back Replacement-Rear in the Seats sub-section of the Service Manual.

At the rear seat back LH (1) or RH (2) heated seat module, disconnect the blue, 8-way connector C2.

Important

If the resistance is measured with the seat still warm, the resistance may vary outside of the specified range since the thermistor resistance varies with temperature.

Measure the rear seat back thermistor resistance between cavities E and F. Does the resistance measure between 280 ohms and 300 K ohms?

If yes, go to Step 11.

If no, install a rear seat back heat element. Refer to the Service Heat Element Installation Procedure in this bulletin.

Measure the rear seat back element resistance between cavities G and H. Does the resistance measure less than 10 ohms?

If yes, the resistance values of the rear seat heat elements are within the specified range. To find the cause of the inoperative/cold heated seat, perform the standard diagnostic procedures in the Service Manual.

If no, install a rear seat back heat element. Refer to the Service Heat Element Installation Procedure in this bulletin.

Service Heat Element Installation Procedure

If a sublet trim repair facility is used, please provide a copy of this bulletin to the repair shop.

Important

Before installing the service heat element to the seat trim cover, verify that the resistance values are within the correct range. Refer to the following table.

Model

Range

Description

ALL

Less than 10 ohms

Seat Back Elements

DeVille

(Base)

Less than 10 ohms

Seat Cushion Elements

DHS & DTS

Less than 10 ohms

With Seat Cushion, LH & RH Thigh Elements Connected

DHS & DTS

Less than 30 ohms

Seat Cushion Thigh Elements

Important

DO NOT attempt to remove the factory heat elements from the seat trim cover. The service heat element is to be installed between the factory heat element and the seat trim cover.

Remove the trim cover with the non-functioning heat element. Refer to the appropriate seat trim cover removal procedure in the Seats sub-section of the Service Manual.

Place the seat trim cover on a clean flat surface with the inside facing out.

FIGURE DHS/DTS and DeVille F/Seat (R/Seat Similar)©

(1) DHS/DTS F/Seat Back Trim Cover -- Inside Out

(2) DHS/DTS F/Seat Cushion Trim Cover -- Inside Out

(3) Cut-lines

(4) Seat Cushion Wiring Harness Cut Locations

(5) Seat Back Wiring Harness Cut Locations

(6) DeVille F/Seat Cushion Trim Cover -- Inside Out

(7) DeVille F/Seat Back Trim Cover -- Inside Out

Use a marker to draw in the cut-lines (3) on the non-functioning factory heat element. Refer to the appropriate illustration.

Remove the wiring harness from the non-functioning factory heat element.

At locations (4) or (5), pull back the tape covering the harness wires.

Use a pair of diagonal side cutters to cut the harness wires as close to the factory heat element material as possible.

FIGURE DHS/DTS and DeVille F/Seat Back©

Important

DO NOT start the cut with a jab or poke.

At the trim cover edge (2), using a razor blade or an equivalent sharp tool, slice through the factory heat element material along the cut-line until a hole is created.

Insert your finger(s) through the hole and lift the factory heat element material (1) away from the trim cover material.

Important

DO NOT cut through seams.

Using scissors and/or a razor blade, continue cutting the factory heat element material along the cut-lines.

FIGURE DHS/DTS and DeVille F/Seat Back©

Fold back the centers (1) of the factory heat element material. Insert the service heat element (2), with the backing paper side up, between the trim cover material and the factory heat element material.

Carefully remove the backing paper from the service heat element. Ensure the service heat element is laying flat.

Unfold the centers (1) of the factory heat element material.

FIGURE DHS/DTS and DeVille F/Seat Back©

Match the edges of the factory heat element material and cover the cut-lines with 3M® Highland™ Cloth Duct Tape, P/N 6969, or equivalent. Ensure the service and factory heat elements are laying flat.

On DHS & DTS seat cushion installations: Connect the two thigh heat element electrical connectors to the center heat element.

Install the seat trim cover. Refer to the appropriate seat trim cover installation procedure in the Seats sub-section of the Service Manual.

On front seat assembly installations: Install the fasteners that retain the seat cushion to the seat adjuster. Tighten

Tighten the fasteners to 9 N·m (80 lb in).

Place the seat assembly inside the vehicle. DO NOT install at this time.

Verify the seat heat function is operational.

Complete the seat assembly installation. Refer to the appropriate seat replacement procedure in the Seats sub-section of the Service Manual.

Parts Information

Model

Part Number

Description

FRONT

DeVille

25740850

F/Seat Back Cushion Heater

DHS & DTS

25715920

DeVille

25740851

F/Seat Cushion Heater

DHS & DTS

25715921

DHS & DTS

25715924

F/Seat Cushion (LH Thigh) Heater

DHS & DTS

25715925

F/Seat Cushion (RH Thigh) Heater

REAR

DeVille LH

25740852

R/Seat Back Cushion Heater

DeVille RH

25740853

DHS & DTS

25715926

DeVille LH

25740854

R/Seat Cushion Heater

DeVille RH

25740855

DHS & DTS

25715927

DHS & DTS

25715928

R/Seat Cushion (LH Thigh) Heater

DHS & DTS

25715929

R/Seat Cushion (RH Thigh) Heater

Parts are currently available from GMSPO.

Warranty Information

For vehicles repaired under warranty, use:

Labor Operation

Description

Labor Time

C7340*

RH F/Seat Cushion Heated Seat Component Heating Element-Replace

1.1 hr

ADD

Diagnosis Time

0.0-0.3 hr

C7341*

RH F/Seat Back Heated Seat Component Heating Element-Replace

1.5 hr

ADD

Diagnosis Time

0.0-0.3 hr

C7342*

LH F/Seat Cushion Heated Seat Component Heating Element-Replace

1.1 hr

ADD

Diagnosis Time

0.0-0.3 hr

C7343*

LH F/Seat Back Heated Seat Component Heating Element-Replace

1.5 hr

ADD

Diagnosis Time

0.0-0.3 hr

C7344*

RH R/Seat Cushion Heated Seat Component Heating Element-Replace

0.9 hr

ADD

Diagnosis Time

0.0-0.3 hr

C7345*

RH R/Seat Back Heated Seat Component Heating Element-Replace

1.0 hr

ADD

Diagnosis Time

0.0-0.3 hr

C7346*

LH R/Seat Cushion Heated Seat Component Heating Element-Replace

0.9 hr

ADD

Diagnosis Time

0.0-0.3 hr

C7347*

LH R/Seat Back Heated Seat Component Heating Element-Replace

1.0 hr

ADD

Diagnosis Time

0.0-0.3 hr

*This labor operation is new and will be included in the next update of the Labor Time Guide.

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION

© Copyright General Motors Corporation. All Rights Reserved.

--------------------------------------------------------------------------------

Document ID# 1059134

2000 Cadillac DeVille

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I would check connections first, followed by measuring the resistance across all the elements and comparing. If one is broken, you should see it. Seems like a fuse or connection problem since all are out.

Wow, Thanks so much for everyone's input I didn't expect that much support. I'll take a look at some of these possibilities

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  • 4 years later...

the ones on my 96 Deville were all bad. I didnt much care for the Deville setup mainly because there is only 2 elements rather than 4. I installed ETC seats in my Deville and now they work perfect. I did a writeup on the info on the elements that shows how and where they fail, etc... very good info in the above post with the TSB. cant get any better than that. Now this is important. the seats dont heat unless you are sitting in them. There is a temperature sensor that detects the heat and activates the elements.

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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  • 3 years later...

I might as well update this as long as it is revived.

In 97 they wired the elements differently.

They were wired individually rather than in series. A little better design because if one element fails it may not take out the whole seat unless it is shorted.

My 97 Deville both seats work but it seems one of the bottom elements is not working on the driver seat. Someday I will have to pull and inspect the elements

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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  • 3 years later...

I have a 2011 EXT The Drivers seat Heat and A/C doesn't work. When I push the button I can hear the solenoid click but nothing happens after that. Same thing with the A/C.  The Passenger seat works fine. GM said it was probably the fans and they run 400 each or so.  Any thoughts on this? Thanks Jeff 

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Good evening. Welcome to CaddyInfo.

I would start a new thread for yours. It will be easier to follow and is pretty different from previous.

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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