Door Lock Problem

[gtgillis]

The power door locks in my 1999 XLT will not lock using the switches on the driver or passenger doors. Strangely, I can open the back hatch and use the power lock switch there to lock and unlock the doors. Since I can lock and unlock from the back I am ruling out the actuators and relays leaving only the lock switches or wiring. I am leaning toward the problem being a broken wire since driver and passenger lock switches act the same way.

Comment? Suggestions?

Does anyone have a schematic of the driver door wiring?

Regards,

Greg

 

[Medic 19]

I have been searching for some help with this issue myself. for me it is only the driver's doorswitch (locking only) that is not functioning. I swapped driver-passenger switches and neither will work in the driver's door but both work in the passenger side. I find it very strange that a 00' EB 4.0 with 55k mi has a wire/wires or connection that is failing. Anyone have any short cuts on where to look first? Known trouble spots?

 

[JIGAWHAAT]

Subscribing
I just encountered the same problem. If I figure it out before you do I will post what was wrong with mine here.

 

[Gatorblazer]

Ok, try this

1. Always check for fuses and grounds, as they are the most common faults.

2.If you pull the switch from the back, place it in one of the doors locations and test it. If it does not work, then you know that it is wiring. (Take what you know works and try to eliminate it from your problem. Taking a switch from the door and putting it in the back area will also do this).

3. Take a look at the harnesses inside of the door. See if you can find anything that just looks weird like burns, buildup, shorts. At this point I would also clean the harness plugs just to be sure.

If non of these are not the problems, then it may be in the main harness. Thats just a matter of looking as well

 

[budwich]

Does your remote work (ie. lock the doors)? Your problem is basically a broken PK/V wire going towards the lock relay in the back cargo panel (drivers side). If the remote works then your problem (with the wire) is closer to a splice... if its a four door, near the passenger door column, if two door near the left rear speaker area. If the remote doesn't lock either, then the problem is likely closer to the lock relay in the cargo panel.

 

[Medic 19]

Does your remote work (ie. lock the doors)? Your problem is basically a broken PK/V wire going towards the lock relay in the back cargo panel (drivers side). If the remote works then your problem (with the wire) is closer to a splice... if its a four door, near the passenger door column, if two door near the left rear speaker area. If the remote doesn't lock either, then the problem is likely closer to the lock relay in the cargo panel.

Yes my remote works. Thanks this is exactly the type of help/info I was hoping for.
Sorry for the delay guys but I moved and have been without internet services. Brent

 

[slpdave]

If you have a Volt/Ohm meter use and exacto to trace through the wires (put one end on the plug on the master control panel pop the trim out of the inside body panel (between the fender and the E-brake pedal, that will give you full access to the wireing harness. Touch one lead to the back of the master control panel, touch the other to an exacto blade or needle pirceing through the insulator to the contuctor on the same wire inside. using the Ohm setting it should read an almost perfect short (0 ohms) if it reads over 100 ohms you probably have a bad wire, do this with the key out and the vehicle powered down. to check for voltage put on lead on ground (any bare metal surface should work or the big black wire going to the master control panel. with your meter set to read volts touch the other to one contact press button is there any voltage? push button the other way, is there any voltage there. with windows it is a + voltage is one direction a - voltage is the other. I found a broken wire inside the harness doing it this way. be sure to use a heavy gauge multifillament wire to replace the piece that is broken and insulate everything properly. DO NOT USE SOLID CORE WIRE to repair the amperage will burn the wire up if you do.

David

 

[SN95GT50]

Can you buy just the lock switch from the dealer? Or, is the window switches and lock a single unit? How much is a new lock switch?

John

 

[Medic 19]

You should be able to get at least the lock switch separate. I know that they are interchangable from driver to passenger, that is how I knew it was a wiring problem and not the switch.

 

[AltimateX]

That just started happening to me too about two weeks ago. Really a nuisance.

 

[gtgillis]

Solution Found

I spent about 3 hours trouble shooting this problem and found the problem to be a splice that was corroded. The splice is located under the trim of the driver side rear door on my XLT. The reason the splice corroded is there was some water in the channel with the wiring harness. I cut off the corroded ends of the wires, soldered them all together and heatshrunk them to protect them from moisture. Now my doors lock and unlock.

I am still looking for the source of the water in the wiring harness channel. If anyone has any ideas please let me know.

 

[Andy94SC]

I spent about 3 hours trouble shooting this problem and found the problem to be a splice that was corroded. The splice is located under the trim of the driver side rear door on my XLT. The reason the splice corroded is there was some water in the channel with the wiring harness. I cut off the corroded ends of the wires, soldered them all together and heatshrunk them to protect them from moisture. Now my doors lock and unlock.

I am still looking for the source of the water in the wiring harness channel. If anyone has any ideas please let me know.

I have this exact same problem with my wifes 99 Mountaineer, only the rear switch works to lock the doors.

I'd like more information on this splice, what color wires? Is it in the door or in the body near the door?

(edit)
I think I found that it would be the Pink and yellow wires from the lock relay, according to these diagrams...

From the looks of things there are two seperate wires that control the lock relay in te first digram, "H" which comes from the rear liftgate switch of the second diagram (and works) and the other is "A" which comes from a splice of the two front door lock switches and the remote entry module also in the second diagram (none of which work for me.)

I am assuming this is the splice mentioned in the post above. Depending how the splice breaks you could lose any combination of those three inputs to the lock relay.

Now to find the location of that splice....

 

[heysimon]

Fixed Mine!!!

This drove me nuts for a year!! If it wasn't for the photos , I would still be working on it. Thank You!!!

 

[FirstFordEver]

This thread certainly pointed me in the right direction. My son's '99 XLT was doing the exact same thing. Kinda goofy the locks "locked" from the cargo area button, but would not lock from the door buttons or remote. "Unlock" worked fine.

Anyway, for the "a man has gotta know his limitations" dept, I took mine to the dealer today. They were well familiar with this issue and they actually located (4) broken splices in the wire...they wondered how it could "lock" at all. The replaced the entire length of the wire, not just a new splice(s) and re-solder.

Just so you know "how much"...3.0 hrs labor @ $80/hr = $240. It's done and done right.

 

[bluestream1]

I had the same problem, and thanks to this thread I was able to fix it. Mine was corroded in the connector that joins the one pink/yellow wire to three. It looked fine from the outside, but was powder inside. I don't think this is from water, but from the process used to join the wire together. The copper on the wire was still like new on either side of the factory connector, so I don't think water was the issue. Maybe the wrong solder was used in the manufacture of the harness.

Here is a pic of the repair after I soldered in a splice and used shrink wrap. Whole job took about 30 min.

 

[gswan]

I have the opposite I can use the lock in both doors, remote, and the back.
But it will not unlock form the drivers door. Took the switch out and jumped the wires
and it only locked.
I can unlock it from the passenger door, remote, and the back.
I fixed the wires for the lock
any help?

 

[gswan]

From Key pad it locks and unlocks

 

[budwich]

Its most likely the same problem as described in detail in these posts.... look at the pictures and schematics and follow the wiring to the same place. OF course, the other likely culprit is a break at the door post.

 

[Velvis]

Does the Sport (2 Door) have the wires running down the drivers side like the above photos as well?

 

[gswan]

I thought i read on a different post that it was behind the panel on the driver side back back seat