deanwaltman

First, thanks to all the folks who posted previously regarding the power seat problems. It was a big help to my project.

My '00 has the 8-way power seat. The rear seat cushion-lifter thingy stopped working a while back, but everything else seemed ok. I finally got around to it after a couple years and with a veritable armload of wrenchs/sockets/tools extracted the seat. I guess you could leave it in the truck and remove the bottom cushion with a 10mm but what fun is that. And, I found like $1.83 in change.

The battery charger set on MANUAL 20amp, a couple of clip leads to the RED and BLACK wires on the white connector (see pic) and the seat springs to life. Forward and back draw about 4 amps. Front lift up and down draws like 3 amps. The offending motor for the rear lift only hums. Up or down. Battery charger shows almost NO amps. Bypass the switch directly to go directly to the motor. Motor still hums. Switch is good... Seems like a motor problem. Spins like a 1/2 to full turn then quits and hums. The plot thickens.

The motor is pretty easy to get out, just a torx for the gear drive and a small flatblade for the wiring connector. Nothing special.

The motor has two phillips screws holding it together. The drive side falls off, with the little square drive cable thing inside. The armature and permanent magnet housing slides apart if you push from the inside. The brushes/end cap come with it. Easy to reassemble but you do have to put the armature in the end cap first, fiddle with the brushes, and then slide the magnet over it. Watch for pinched fingers here as the magnets are strong.

Here lies the real problem. There is a thermistor in the end cap. I've seen it referred to as the brass plates or maybe even a fuse, but it's the component that limits the current when you run it to the stops. The resistance goes up and stops the motor from burning up. While I am yet to find a replacement, it would be quite an undertaking to replace it. The brush copper-braid is 'attached' to it so you'd have to rivet or screw the braid onto a new one. Not really doable in the limited space there. So, I have done what most others have done, and solder the 'plates' together on the edge. You can see a little blob of solder on the edge of the copper at about 11 oclock in the end cap pic. A word of caution: There is NO current limit now. If the switch gets stuck or the operator hammers down on the switch to the stops then I hope the fuse gives up before there's a fire. Myself, I will take the chance since I'm usually the only one that drives this truck.

kawi600

What about a snap-disc type thermostat? Theyre cheap and should keep the motor safe. Could also fab up some contact switches to cut power in the right direction at each extreme of travel.

deanwaltman

That would work. A self-resetting circuit breaker maybe also. I realize there is more than a single way to really fix this. I hope that the info here prompts someone in the future to find a readily available replacement component and post the part number.

Limit switches would of course work too, but might have some serious engineering and time invested.

Maybe my thread title should be work-around instead of fix.

deanwaltman

While I had the seat completely out of the truck, I went ahead and repaired the power lumbar.

It is basically an air bag with an electric motor to fill it. Releasing the air is controlled by some sort of electric switching thingy. It pumps up the bag when pressing the top part of the rocker, and releases the air when pressing the bottom of the rocker. Fairly simple.

The seat cloth is held together with a plastic folding clip/bar arrangement at the bottom of the back of the seat back. It appears to be sewn -it is not, and a little prying on the edge got it to separate and unfold. I quickly folded it back up to make sure it goes back together. It did. After getting some room by carefully working the fabric up about a foot, you can expose the air bag and another black sack which houses the motor and valve. I had to cut a couple zip ties of the wiring to get enough length to pull it out. There's a black plastic backing plate that clips to the seat also. From there, you can un-staple the black bag and extract the motor/valve assembly. Mine was frozen up with rust. It looks very similar to a Holley fuel pump - vane type pump. There is a black plastic wedge that holds the wires to the cap. The pcb under the black cap unplugs from the motor. Be gentle and pull straight off.

I disassembled the whole thing, cleaned, lubed, and reassembled using all the same parts. I double checked operation just like with the power seat motors (battery charger set on MANUAL 20Amp). Motor works and air bag holds air. Nothing special about reassembly.