Hey all, I typically spent my time in the PSD and Bronco forums, but I just picked up an '03 Expedition for my wife and have a couple issues to fix.

1. First the 3RD row seats won't fold down, no clicking, no sounds, nothing. I the fuses are good and there is power at the fuse box, but no power at the motors or switches. Based on continuity tests with my multimeter, the switches appear to be working properly. The biggest problem I have is that I cannot find a good wiring diagram for the seats. I found this link that talks about relays for the seats, but according to my manual there are no relays (at least not in the passenger fuse box). If there are relays, where are they? If not, what else should I be looking for?

2. [Not a brake problem. See update below]. The second issue I am pretty sure is with the ABS. It's a random pulsating feeling in either the front or rear, typically happens between 50-65 mph and less frequent above that. The best way to describe it is as if you are driving on the rumble strip. It only happens when not braking and does not feel like the brakes are being applied. The front pads appear to be new, so I'm thinking that someone may have screwed something up when they did that. What should I be looking for?

 

You might check the tranny. When it shifts between 3rd and Overdrive, the torque convertor can shutter. My 99 did that until I flushed the system and added Lucas tranny additive. No issues after but it took several hundred miles to resolve.
Felt absolutely the same as rumble strips too.

 

I don't think it's the tranny because I can distinctly feel it in the front and then sometimes in the rear. If it was the tranny, it would always feel like it's coming from the same location.

 

Well, it looks like you are right. I got to drive it some more yesterday and if I would let my foot off the throttle a little bit so that it would shift into OD, then gently press the throttle to make it shift out of OD, it would shutter every time. Looks like I will need to do a tranny flush soon.

I still need a wiring diagram for the 3rd row seats/BSM. Right now I think it's the BSM that is cutting the power to the rear seats, but I don't know what to look for under there. It doesn't help that wiring under the drivers kick panel and around the BSM has been hacked/spliced by someone.

 

Ok, so just to correct myself the BSM/VSM, or what ever you want to call it, is under the passenger side kickpanel. I tested the wire comming from the VSM for the 3rd row seat relay control and it is only putting out ~2.5v, but as soon as you open the rear hatch or rear divers side door it drops to 0v. I have no idea if this is correct or not. Anbody know what it should be?

 

Oh, and here is a pic of my Family of Fords....

 

It's been a while since I looked at the seat switch but I believe it's 5 or 6 wires. I THINK, haven't looked in a while but I will look when I get home
its

1 input 1 output for each seat
1 wire that goes dead like you said when you open the lift gate. That wire locks the seat controls when the gate is closed.

It's a pretty basic system for them. I think they can reverse polarity to move the seats the other direction so a relay might be involved.
It's been several months since I was back there though but I did test the current when I was in there just to see how it works and remember it being pretty simple

 

Just posting an update so that others who might have the same issue can find this thread and an answer. So I have traced the problem with the seats to the tan wire (Circuit 1951, third row folding seat relay control) coming from the VSM (Connection C2113c, Pin 8). Incase others are having a similar issue, here is how the system works for the 3rd row seats:

1. Power is supplied from the fuse box (fuses 104 & 117) to 2 relays in the pillar behind the passenger rear door.

2. The relays are controlled by the VSM with a constant power (circuit 729, RD/WH wire) and a ground (circuit 1951, TN wire) that is only supplied when either the rear hatch or rear drivers door are open.

3. From the relays, voltage is supplied to the switches, which will alternate power and ground to the motors to operate in both directions.

For me, the issue was that I was not getting a ground to activate the relays. Using my multi-meter, I tested both ends of the tan (TN) wire coming from the VSM to the relays and did not have continuity through the wire. So I began trying to trace it through the harness for any obvious signs of breakage but found none. So I picked a couple of key locations to cut the wire and retest for continuity. I found the break to be somewhere under the plastic cover by the passenger seat. So I soldered a new wire to the old one and used the old wire to pull it through the harness. Then I cut the old wire off and soldered and heat shrinked the new wire to the 2 sections of good wire still left. Then I just needed to rewrap and tape the entire harness and put everything back together. The seats work fine now.

Out of curiosity, I took the old wire and inspected it for obvious signs of wear, but all I found was a couple of spots where it looked a little bulged with a greenish blue color on the outside. Using a knife, I cut away the insulation and found that the copper wire had completely oxidized inside. Just a bunch of greenish blue power.

 

Thank You for taking the time to post what you found and your solution.

 

Sounds like you have the shuddering figured out, but I just wanted to confirm that I had the same issue with my F150 4x4 and a tranny flush and friction modifier fixed the problem.

 

Oh, and very nice Ford collection you have there!!!

 

That's good to hear. I haven't fixed the tranny yet, but I'm pretty convinced that I have the same issue you did. Just need to find some time to fix it.