Hey all, I just joined yesterday. I bought a nice 2000 Excursion with the 6.8 V-10 a few weeks ago, and got it really cheap because it had a few things the previous owner just couldn't figure out. I've gotta say, this forum is the best for finding info on Ford trucks! I've already resolved a couple of issues without spending a penny thanks to the wise (experienced) minds here LOL

One issue the PO couldn't resolve is the passenger side rear window--he recently spent $800 having all new lock actuators and window motors put in because a couple of them had quit working, but the right rear still won't go down and he didn't want to spend any more $$ figuring out why. All other windows function normally, and I believe the right rear would go UP if I could ever get it down because the problem is only with the lowering voltage, not the raising voltage.

First I checked at the right rear motor connection and toggled the right rear door switch--I had 12v to raise, but nothing to lower. I swapped switches with the left rear door, a known good motor and switch...same result. I checked voltage at the INPUT to the RR switch....same result--I get 12v to raise, nothing to lower. So I moved to the next logical place, the master control (drivers door switch). On the output side of the switch, voltage toggles between +12v and -12v as it should to raise and lower. Everything is good from the time it leaves the driver's door switch, so apparently I'm losing my lowering voltage somewhere between the output of the driver's window switch and the input of the rear passenger window switch. I checked for chafing/loose/corroded wiring all the way from the B-pillar to the right rear door switch, a common cause of this symptom, and everything looks fine for that stretch of wiring.

Before I go tearing into interior panels and tracing the wiring inch by inch, has anybody else had this same issue and resolved it? Is there maybe a relay specifically for the right rear window, or a connection/module that's been known to cause this symptom? Thanks!

 

Double check the grounds and if that's not it run a straight wire from the front switch where you have the correct power to the motor in the back and see if it works fine. If it does then you know your issue is in the OEM wire somewhere and you get to start pulling panels

 

Apoc is right in saying to check the grounds but let me expand a little. There are 2 wires on the motor. When you hit the switch for UP one wire goes hot and the other goes ground, when you hit the switch for DOWN it reverses and the one that was hot when up is now ground and vice versa. You could have power but no ground going to the motor. It is easy to miss when you see you have power. I like to use a test light in place of the motor with the clamp hooked to one wire and the probe to the other because a test light doesn't care about polarity and proves power and ground if the light lights. Obviously if you have proper power/ground out of the switches but not at the motor it is time to start tracing. I can get you wire colors if needed.

 

Water can get onto the switches from the window washer and mess them up also.

 

Good tip and I may stick a test light on it to be sure it's getting enough current to actually run a load as it exits the driver's switch....I know that reversible motors like those used on power windows don't have a "ground" per se...the module controlling them provides the ground internally and as required with diodes, and the polarity of the wiring to the load is switched within the control module to provide the multi-function at the load.

I work as a mechanic at the Ford Assembly plant that builds the Ford Escape and generally prefer a DVM to check electrical issues, but it's one weakness (unless you use it as an in-line ammeter) is that if a single strand of wire or small point of contact exists, you'll show voltage--but that single strand/contact point can't carry enough amps (current) to run the load at the end. But the reason I shy away from test lights, especially in automotive applications---I can tell you firsthand (not me but a co-worker) that using a test light at the wrong spot can potentially fry a control module or even worse, set off your air bags.

I found another post on this forum where people found chafed wiring inside the DRIVERS door rubber boot between the door and the body...I'll look there first, and if everything looks okay I'll look next for where the control module is located and grounded :-) But it seems like if it were a grounding issue it would affect all windows, so I'm more leaning towards a "broken wire" issue.

 

Best cheap tool I used in the avionics world was a load light. You can have full voltage and the bulb will barely glow due to current. They are easy to make with a bulb and wires.

 

The problem with the internet and the anonymity that comes with it is the lack of personal knowledge about those posting. After I typed my response I thought "maybe he knows what I am talking about already, I hope he doesn't take offense." Thanks for not being offended.