2004 - Seat Heater shuts off after 1-second.

JRMedved
Last seen
Joined
Aug 26, 2018
Thunderbird Year
2004
On my '04 Thunderbird, upon activating the driver's seat heater switch to the HIGH position, the (amber) HIGH indicator light in the switch comes on for about 1-second then shuts-off and there is no heat to the seat cushion. It works fine on LOW setting. Passenger seat works fine on either setting.

Is this indicative of a particular issue with the switch, module, or element? I cannot locate anything specific to this phenomena in the workshop manual.
 
On my '04 Thunderbird, upon activating the driver's seat heater switch to the HIGH position, the (amber) HIGH indicator light in the switch comes on for about 1-second then shuts-off and there is no heat to the seat cushion. It works fine on LOW setting. Passenger seat works fine on either setting.

Is this indicative of a particular issue with the switch, module, or element? I cannot locate anything specific to this phenomena in the workshop manual.
I'd be inclined to suspect the switch, if the connectors are the same you could swap them and test the theory if you think this is a good idea. Unfortunately, it's a moot point, because you will have a tough time finding a replacement switch if that is the problem. None have been for sale in 6 months on eBay. In the past 20 years, I don't recall this issue being asked so it is not a common issue.
 
I'd be inclined to suspect the switch, if the connectors are the same you could swap them and test the theory if you think this is a good idea. Unfortunately, it's a moot point, because you will have a tough time finding a replacement switch if that is the problem. None have been for sale in 6 months on eBay. In the past 20 years, I don't recall this issue being asked so it is not a common issue.
I actually came across a new switch. Replaced it, and it resolved the notice symptom. However, I feel like the bottom heating element is weak, so not much (if any heat) coming from that pad.
 
The driver and passenger heated seats share a common battery and ignition feed. When the heated seat control switch is pressed with the ignition switch in run or start, a momentary ground signal is sent to the heated seat module. The heated seat module then supplies power to the heating element circuit.

Seat Heater Element 1.jpg

Seat Heater Wiring Diagram 1.jpg

The cushion element and backrest element are wired in series and powered by the same output. The heated seat module is designed to heat the seat to 99.5°F in low setting and 107.6°F in high setting and maintain the temperature until switched off. This temperature is maintained by the heated seat module monitoring the temperature sensor, located in the seat cushion element, and adjusting the current flow to the heating elements.

After 20 years of getting in and out of the car and sitting on the seat, the seat bottom element is probably damaged and will need to be replaced. The part number of the seat cushion element is 3W6Z14D696BA. Since the dealer is required to supply parts for only 10 years, I'm sure that it will be difficult to find a new seat cushion element from a dealer.

doug7740
1955 Thunderbird Blue

Seat Heater Element.jpg
 
You might have good luck with an experienced auto interior shop had one repair one on the bottom of a bmw x-3
 
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