Heated Seats inoperative still!

[dksob81]

Where to start...lol

I've been having problems with the drivers heated seats - they just don't work. I started to troubleshoot last winter but then spring came pretty quick and just gave up now it's getting cold again and I really want the heated seat to work, the passengerside works just fine but not the driverside.

Well yesterday I ran some test according to my FSM, check the seat cushion for continuity between the 2 driver circuit cavities and it's OK (1.5 ohms). Then checked for continuity between one of the driver circuit cavities and the seat cushion frame and got nothing - this is good.

Then check for continuity between the heated seat driver circuit cavity and the ground cavity of the seat back and it was OK (.8 ohms). Then checked for continuity between the driver circuit cavity of the seat back and the frame and got none - so this is good as well.

Then checked the Seat Sensor. Using and ohmmeter checking for resistance between the heated seat switch output circuit cavity and the ground cavity and should get between 2 kilohms and 200 kilohms and I got nothing. So I figured the heated seat sensor was the problem, so I took the seats apart yesterday and found one of the wires for the sensor was broke so i checked the sensor to see if it was good and I got nothing no resistance at all, so I just hooked a 2.2k resistor in it's place. Well excited that this is going to fix the problem I put the seat back together and rechecked all my reading, got 1.5 for the seat cushion, 0.8 for the seat back and 2.16K ohms for the sensor - good everything was still working. I put the seat back in the jeep and connected it and still nothing. Rechecked all my reading and everything is good but still no heat. I swapped the Heated Seat Control Module with the passenger seat and still nothing.

Anyone have any suggestions.

I seen before in some other posts that the readings for the heating elements should be between 0.9 and 1.4 ohms. Mine reading were a lil out but I don't think thats the problem. And also someone had their seats fixed at the dealer and they replaced the sensor with a 1k 1/2 watt resistor. I used a 2.2k 1/2 watt because the FSM said it should be between 2 kilohms and 200 kilohms.

[dksob81]

Well I did some testing this morning before work and found some power issues from a wire at the HSCM (Heated Seat Control Module), these were tested with the switch on high and engine running..

DRIVER SEAT
BLACK/ORANGE - Heated Seat Driver (0 volts)
PINK/DARK GREEN - Fused Ignition Switch (13.4 volts)
RED - Fused Battery (+) (13.5 volts)
LIGHT BLUE/WHITE - Heated Seat Switch (3.3 volts)
BLACK - Ground (0 volts)

Passenger Seat
BLACK/ORANGE - Heated Seat Driver (13.3 volts)
WHITE/BLACK - Fused Ignition Switch (13.3 volts)
RED - Fused Battery (+) (13.3 volts)
LIGHT BLUE/WHITE - Heated Seat Switch Output (5.3 volts)
BLACK - Ground (0 volts)

Now you can see that the BLACK/ORANGE wires should have battery voltage with the key in the ON position and the seats turned ON, but the driver seat gets no power at this wire. It is actually a ground (or grounding out somewhere) I can actually use this as a ground point to test the other power wires and I get power, but when I disconnect the 4-way harness from the seat cushion the ground goes away - so now I know the wire is grounding out inside the seat cushion somewhere. But the thing is when checking the seat elements I checked for continuity between the drivers circuits and the seat frame and I get nothing - meaning neither of the driver circuits are grounding to the frame of the seat. So whatelse could it be grounding to.

[bruno2260]

I have a '96 GCL. My driver seat heater went out too, and I want to get it working before winter. I haven't looked at it yet. I just figured it was the element(s), or a inline fuse or somthing under the seat. But according to your tests it might be more compliated then that. I plan on taking my seat out this weekend, I'll let you know what I find.

[dksob81]

Bruno,

You can do a few test without taking the seat out this way it may help you track down the problem before tearing it apart. I took mine apart 4 times already and still haven't go it to work.

All the wiring harness for the Sensor and each element are located underneath the back of the seat.

There is a 2-way connector (green) this is for the seat BACK - check for continuity here - if OK seat back element is good. If not OK, then there is most likely a broken wire that needs repaired.

There is a 4-way (black) connector - this is for the seat cushion element and the heating sensor. The 2 dark color wires are for the sensor and the light color wires are for the element. Disconnect the connector and test for continuity between the light color wires you should have continuity - If not a wire is broken (this is very common). Now check for resistance on the 2 dark color wires - you should get between 2K and 200K ohms of resistance. If not then the Sensor is bad or broken wire.

[dksob81]

Ok well I got the heated seat working.

I tore it apart after work today and tore into the wiring harness thinking I had a short on the BLACK/ORANGE wire from the HSCM to the 4-WAY connector. but nope there wire was good. So I tore the seats apart and check all the connections and solders (although I knew they were fine from the tests I did). then I rechecked the sensor that I eliminate, actually it was still in the seat I just by-passed it using a 2.2k resistor well I checked for resistance on the sensor by probing either side of the sensor and I got good resistance (alot more then with the resistor), hummm but when I checked the other day at the little grey wire that were connected to it I got nothing, well I cut those wires off when I connected the resistor. So I took the resistor out and soldered the BROWN/RED wires (from the 4-WAY connector directly to the Sensor (instead of to the grey wires like it was from the factory) and double check my resistance reading at the 4-way connector and got about 7 ohms.

I was under the impression the higher the temp got the higher the resistance would be but actually it is the oposite of that. So if I were to use a higher resistor like 10K or even higher up to 200K it would have probably worked fine.

Well I put the seat back together and put it back in the jeep and turned the seat on and immediately checked for voltage at the BLACK/ORANGE wire and got voltage then a few seconds later checked the seat and it was working GREAT!

I hope this helps someone else, remember if anyone decides to eliminate there sensor make sure to use a big enough resistor (I would use as high as you can get above 10K (1/2 watt) and up to 200K (1/2 watt), but not over 200k.