Neither of the rear windows in my crew cab would go down when I got the truck. A few weeks ago I replaced the motor in the right rear door. The NAPA rebuilt unit came with a gear box that had the mounting holes stripped out so I took the gear box off my motor and put it on the new motor. By the way, I'm not talking about the actuator arm assembly here, I'm talking about the gearbox the attaches to the motor itself. Then the gearbox attaches to the actuator arm assembly.

Anyway, the window seems to move freely in the track when the actuator arm isn't connected to it so I hooked everything back up and it all worked as it's supposed to, for a week or two. Then suddenly the window won't go down again. I could hear it trying to move. I checked and I'm getting voltage to it, and the voltage was low enough that it was believable that the motor was drawing current. I did try hot wiring the motor direct from the battery with the same result, so I don't think it's the wiring.

So I took everything out of the door again and, what do you know, the motor works fine when I hold it in my hand. So I put it back in and everything works fine for another week and a half, and then today it won't go down again.

Any ideas where I should be looking?

 

You said the motor worked fine when you held it in your hand... was the gearbox attached to the motor when you did this? If not I'd say either the gearbox or the actuator arm is getting bound up, and you moving it around to take the motor off was enough to get it freed up again. Could be the motor itself too (could have a dead spot on the commutator) but I'd suspect gearbox problems first since it's "rebuilt" and came to you already screwed up.

 

The gearbox is not rebuilt (which might make it even more suspect). It's the one that was in the truck when I got it. It didn't seem like there was anything wrong with the old gearbox (the old motor didn't make any effort to move when I put power to it). I couldn't figure a reasonable way to mount the rebuilt gearbox to my actuator arm assembly, so I put the old gearbox on the rebuilt motor and installed that. I returned the burned out motor and the rebuilt (new) gearbox for my core charge.

I don't think it's the actuator assembly that's binding up. There was nothing funny looking on any of the gear teeth (actuator sector gear or gearbox pinion) and the assembly moved freely.

And as I said, I looked over the gearbox when I first took it apart and it looked OK. But since the window didn't work with this gearbox before and doesn't (always) now, it certainly seems suspect.

Any other thoughts? Or anything specific to look for in the gearbox?

 

Broken wire where they pass from the cab into the door

 

It's not wiring. I can hear the motor grunt a little when I hit the switch. And the first time it did it I unplugged the motor and ran power and ground directly to the motor connector. Still just the motor grunt but no motion.

 

If you have a bunch of broken strands, the motor will work intermittently. The "good" strands will carry enough current to make the motor strain, but not enough to make it work. It is when the broken wire touch, you have enough amperage to run the motor properly

 

That ^ is a possibility too. Faulty wiring with marginal connections can carry just enough current to make things appear to be working but fail to operate with any load on it. I've seen this happen a few times with various things.

 

OK, I'll try bypassing the door wiring again. Maybe I did something wrong the last time. But hotwiring the motor directly bypasses the wires you are saying are suspect, so if that's my problem then there's also another problem that gives the exact same symptoms when I hotwire the motor.

 

Let's see: you used a new motor on your old gearbox and actuator. The old motor didn't work at all. The new one did but then quit, yet started working again when bench tested. Right after it quit you could hear it trying to work, although it didn't have enough torque to move the window.

So, you have an intermittent fault that is either robbing the motor of power, or putting too much strain on it. That's why I agreed with Brad, because if it works fine when wired direct to power, then something in the truck either ain't letting it get the full amount of power it needs, or something mechanical is binding up intermittently and overloading it.

 

I didn't say this before, but yesterday I did try to pull the arm down while I pressed the down button. Didn't move. I still heard the motor grunt a little, but I didn't feel anything in the arm. (Currently the door panel is not installed, but everything else is put together, including the door window switch hanging on it's harness.)

So if it's a mechanical bind it seems like it's probably in the gear box. Again, this is the same gear box that was in it before when it didn't work, so that could point to it. But I did look it over pretty closely when I had it off the motor before deciding to re-use it and it looked OK to me then.

It's still possible that it's wiring I guess. Maybe I had a poor connection when i hotwired it. I don't think so, but then again, if everything I though about this was right the window would be working!

I'll probably try hotwiring it again tonight. Might not get around to doing anything more involved until the weekend though.

 

Definitely not the wiring. I soldered connectors to wires so I could plug them into an auxiliary fuse panel I installed, and one of my replacement motors came with a selection of connectors that included the mating connector for the motor. So when I hotwired it tonight all of the connections were good ones, no alligator clamps or anything. Still wouldn't move.

Now I've got my son's XJ front axle U-joint out, so we'll see if I get time to work on the window this weekend or not. At least it's stuck closed!

 

I'm still frustrated. I started taking the motor/actuator out of the door yesterday. As I got each bolt out I checked to see if the motor would work. Nothing after the first two but after I took the second-to-last one out the window came down!

And to explain the bolts, when I took it out the first time I drilled out the rivets. When I put it back in I used bolts. I bought 1/4 x 3/4 but they were too long so I cut them off to 1/4 x 1/2.

One thought I had was that maybe that bolt was hitting something, but I checked it pretty closely and there's quite a bit of clearance.

Second thought is that something somewhere else was hitting and taking all but one bolt out let the actuator shift away from it. But the holes all still lined up, so it certainly didn't move far.

While I had it out I pulled the gearbox off the motor and looked it over really well again. Still didn't see any glaring issues. No binding, nothing I could see loose inside that might be getting stuck occasionally, no damage on the gear teeth.

The only thing I noticed at all was that there seemed to be a little bit of runout in the pinion gear, so it's possible that it was causing some bind with the sector gear (although it sure seemed to move smoothly as I cycled in after I removed it, before I took it apart). So I tried to put the gearbox back on the actuator shifted as far away from the sector gear as the screw clearances allowed. Now there's just a little bit of backlash, so there shouldn't be any binding.

Well, it's all back together now and it works again. We'll see what happens now.

 

That didn't take long. It didn't work the first time I drove the truck after fixing it on Saturday. Now I have a little more info, but still don't know where the problem is.

Today I loosened all 4 bolts holding the actuator to the inner door panel and it still didn't work. Then I completely removed the bolt that had made it work when I removed it on Saturday (the back lower bolt). Still didn't work. But when I took that bolt out I had to twist it all the way out, the actuator was rotated hard against the bolts. Then when I took the top rear bolt all the way out (again twisting it all the way out) the actuator shifted (I had already loosened but not removed the two front bolts). Then the window operated fine. I didn't have time to pull the actuator out of the door tonight so I put the bolts back in and tightened it all up again.

So it's definitely a mechanical bind, but any guesses what is binding? Everything seems fine when it's out of the door.

 

Just to document in case anyone stumbles on this later in a search...

Still no resolution. I saw another thread (https://www.ford-trucks.com/forums/1...w-problem.html) that seemed promising. But that's for front windows. The gearbox on my rear window motors is very different. I took it apart and looked for the same thing, but it's completely different inside, and there was still nothing apparently wrong with the gearbox.

At this point I need to get my door back together so it's easier to use as a door (the inner panel has been off for about a month). Besides, I won't be needing to open that window for a few months now anyway (Minnesota winter coming).

I think my next step will be to get a new motor/gearbox and try that. I don't see anything wrong with mine, but I don't see anything wrong at all and it still doesn't work. So obviously I'm not seeing something. I'll come back and update this thread if/when I learn anything more.

 

I realize that I hadn't updated this. Not that I learned anything, but I always hate searching and finding threads that just trail off without any conclusion. The next spring the window quit working again. I pulled the actuator out again and poked at it a little without learning anything. But it's been over a year since then and it keeps working. I keep expecting it not to some time, but so far it works. So sorry, this thread does sort of trail off with no conclusion.