Hello. I am new to the site. I am currently having problems with my heated seats. They have never worked since I bought the truck. I doubt the seat elements would be burnt out due to the low miles on the truck when I bought it. I have checked both fuses and they look great. When I press the button on both the drivers and passenger seat the LED light does not come on I disconnected the seat module to see if I have 12 volts. I have 12 volts in the second terminal on the top row always, the rest have nothing. I can not get a ground anywhere in the heated seat harness.
I am also having a problem with my auto dimming mirror and compass not working. Can all three of these be related?

where does the heated seat harness ground to?
I am hoping that somebody has a wiring diagram of the heated seat system

Thanks

CanuckChris

 

How did you check the fuses? You can't just LOOK at them, you have to use a meter.

 

There is possible and probable for having a broken filament in the heated seat element.

With a 2002 I would not rule it out based on millage only, best to test.

The bottom and back seat elements are in series.

On the heated seat module that you checked for power, you want to use an ohm meter to check from the violet w/ light blue stripe wire to the yellow w/ light blue stripe wire. If it shows an open, you have a broken filament and that is why they will not turn on.
- It is not "burnt out", just a broken wire in the filaments.

Next to check is that you have +VDC from the hot in run position cab fuse # 23.
This is up behind the switch on the side panel on the seat, it is white w/ light blue stripe wire.

The + VDC on the connector sounds like the hot at all times from engine compartment fuse # 118.
- That is if you held the connector with the tab up, 2nd pin top row is terminal #4 with a Red w/ Black stripe wire.
- This also goes to the heated seat module, terminal #6.

The ground for the seats is from G200 in the passenger side kick panel, a lot of things ground there, including the day / night electrochromatic mirror.
- Might want to remove the plastic cover for the passenger side kick panel and check that ground lug.

On the connector it is terminal #8 black wire. At the switch on the side of the seat, there is no ground.

As posted above, looking at a fuse does not tell much, best to check the fuse with it installed, key in the required position ( some are run only others, run / assy, some all times ) and check for + VDC from each pin on the back of the fuse to a known good ground.

Diagrams :

 

Nice response, Mr. SSc!

 

Thank-you for the great information scully. Thanks to the diagram I have found the problem. I started out by checking the ground from the seat module to G200 and that was ok. Then I checked the fuses (not by just looking at them) with a meter. Again they all checked out fine.

I found that I was not getting 12 volts in the HOT run wire. I tested it at the passenger side kick panel and did in fact have 12 volts. I began to cut open the harness under the sill of the passenger side drivers door. The HOT RUN wire splits in three in a junction at this point. One wire goes to each heated seat and one goes up towards the roof of the truck. I stripped back the insulation and re soldered the connections and sure enough, both seats started working again. This was also the reason my overhead compass and auto dimming rear-view mirror were not working.

I love when you fix something and discover that you fixed 2 other problems at the same time. I hope this helps somebody else in the future

 

Thank you for the follow up with the great pictures.

the next member with similar symptoms will be thankful for your info.

 

thanks bro, hope all is well with you & the Fam.

 

I would like to independantly wire up my 10 way heated/cooled seats from a 2012 that I have installed in my 2011 XLT Super Crew. At least the heated function. I have removed the memory functions from the drivers side and thanks to your very helpful wiring diagram have reconnected the switch to the motors - now both seats are installed and working fine. Would like to hook up the heater functions to aftermarket switches that do not communicate with the Truck. Any help would be appreciated