I went through the usual with the door lock actuators and replaced them, first with aftermarket units that failed within a year and then with new Motorcraft replacement units, because I was tired of taking the door apart and found removing the lock/latch mechanism to be a major PITA!

Now, either door switch (I do NOT have wireless remote locks) will unlock both doors, but neither will lock either door, except that the driver's door switch may occasionally unlock both doors if I rock it back and forth from lock to unlock. The actuators seem to snap up and down cleanly when I get them to work.

I'm guessing this is a door switch failure, the truck is 17 years old with 230,000+ miles and I use the lock/unlock all the time. But is there a way of telling which switch?

Thanks, for any input!

 

Assuming your rig is ~ year model 2001, attached please find the diagram for the lock circuit. Looking at the layout a voltmeter probe exercise, assuming the back side of the switches are reasonably accessible, would be a good start. Failing being able to do that and going into part swap mode, which one to swap 1st is a toss up. Each switch is responsible for acting as a pass thru. (Please try probing with a voltmeter or simple DC light probe first.) Good luck!
F-250, year 2000, 2 door pickup, Lock Wiring

 

Yes you can test all points to see if the correct voltage is where it needs to be. The other option is to buy 2 new switches, or even just one and try it on each side to see if the problem goes away.

 

The early trucks like you have had an issue with wires breaking at the door jambs. Pull back the black boot between the door and cab, very carefully look for cut wire, a bulge in the casing or anything that looks "not" normal. On my dad's 2000 crew cab all four doors had at least one wire cut or broke through after all these years. I also fixed a 99 and another 2000 for friend's of mine with the same issues

 

Thanks, everyone! Obviously, the place to start is at the switches since I wouldn't have to pull the door card. With the diagram it should be quite easy to isolate.

It could also be a broken wire, but I'm sure hoping not! Accessibility isn't good on the cab side of things down there, I know because I fished five more wires through there for clearance, turn signal, courtesy lights and mirror heat. I'm hoping that didn't create a problem, Boy Howdy!

I've found switches listed for the left (driver's) door, but not the right (passenger's.) Does anybody know if both doors use the same part number?

 

I'm like 99.99% sure they're the same on both sides. When you take the doors apart see if you can find part numbers on the switches to verify.

 

Start on the driver door switches EVERYTHING goes through the drivers door switch. It's usually the drivers switch OR a messed up wire like I said. On my dad's it wouldn't work then it would work for a day or a few weeks. But a big bump and it would quit again. Took me a year to figure out the ground was half broken going through the drivers side door boot. Ten minutes later with the solder gun and some heat shrink and all has been good

 

My plan of attack:
1) WAIT FOR A WARMER DAY (Today wasn't too bad but my furnace in the house quit and fixing it took priority. Otherwise we've had highs in the single digits (both + & -)and the locks aren't that important. Besides plastic parts don't like to be messed with in those temps!
2) Start with the drivers' side lock as SuperDutyScaler suggested. Then the passenger door lock. (Locks are easy to get to without tearing the door apart.)
3) Disassemble the passenger door. This side first because manually operating the lock causes the dome light to turn off/on dependent on the lock position. (If there is a wire problem this is likely a hint as to where it is!) Whatever gremlin is messing with the dome lights when I operate the lock manually is in this door, and could be indicative of a ground problem. It has to be investigated anyway....
4) Disassemble the driver's door if the resolution isn't found in the preceding operations.
5) Report here when the problem is solved.

 

I checked the switches (step 2.) The passenger switch is not passing current to the actuator "motor wires." The driver's switch is working correctly, verified with continuity and voltage tests. I disassembled each switch and cleaned the contacts with electrical contact cleaner. The passenger door switch still does not pass current.

I have confirmed there is a separate switch with a different part number for each side. Either switch will fit either door, but the lock/unlock functions will be reversed if the switches are installed on the wrong door. Looking at the wiring diagram confirms this.

There is a separate pair of wires for each lock motor, so a broken wire in the circuit back to the either door motor won't keep the other door from functioning.

I've ordered a switch and will update after it is installed.

 

I just love it when I hear someone actually diagnose something instead of just throwing parts at. Most only want to go the easy parts swap route.

 

Thanks! That is one of the reasons I do my own mechanical work. Too many trips back to a "mechanic" to have another guess disproven with an expensive and unneeded part, plus additional labor expenses and loss of the use of the vehicle for a day....

 

Here's the promised update: I ordered the switch from flee-bay. (PayPal debited my card RIGHT AWAY!) Seller didn't respond for a week, and then didn't reply when I messaged him asking where the part was, but flee-bay informed me I would get a credit to my card within 48 hours. Four days later and calls to flee-bay and Pay Pal resulted in a runaround and a litany of excuses. Eventually, Pay Pal informed me the credit was in my Pay Pal account, only they already knew I have NEVER had a Pay Pal account. Three days later, I got a notice the credit was "pending" (on a Friday, of course) at my bank. Eventually, the following Tuesday the credit was posted. Once bitten, twice shy!

In the meantime, I reordered the part from an on-line retailer. It took nine days to arrive. So JUST NOW I'm able to report on the repair. I installed the switch (passenger side) without any problem, but the doors still unlocked but would not lock. I re-tested all the wiring, even though the locks functioning at all is a good indication that it all was OK. You can see that if you study the diagram. That isolated the problem to the driver's door switch. I took the actuator (top) off the switch (tricky but doable, and no problem with everything falling out.) I could make the doors unlock sometimes pressing the detent the cam on the actuator moves, and noted that it worked when I pushed it towards the outside of the switch. I unplugged it and pried the reeds in that side of the switch towards the outside of the switch. It worked. I re-assembled the switch and it has worked fine for two days. A recurrent failure will cause me to order a new switch, but for now I'm going to see how far it will ride!

Thanks to "Super Duty Scaler" and "jetty" for your help! I know more about this now than I want to!!

 

I'm tagging onto this thread because our 2000 F250 cc 7.3 XLT door locks just started acting up today. I have a Viper alarm and with the door locks inop, it's easy to set off the alarm and look suspicious. Everybody carries in Texas so that's a bad thing.

We benefited from this thread to check the causes that y'all had. But it looks like our problem must be something else

1. Damaged wires in door jamb. Not in our case. The big rubber tube is in great shape and flexible enough to allow a good inspection. The wires don't look bad at all.
2. Driver power door lock switch. We removed it and took it apart. Everything is shiny clean in there and the copper flex contacts work with audible clicks. If I push on the switch, I can see the connection being made.

There is one oddity. If we pull fuse 26 under the hood (it's fine) then reinstall it, the driver door locks. If we do it again, the other three doors lock. These are the only signs of life that we get out of the door lock system. This suggests to me that the cause may be electronic, not electric. I heard of an electronic module under the dash that costs a fortune and requires coding to install. I hope not.

All four door lock actuators in the doors were replaced last year, as preventative medicine. Our daughter drives this truck to college often, so it's got to be right. We pulled the door lock switch out of our 2004 to compare, but it has different connectors.

I would normally proceed by replacing the driver door lock button, but it looks perfect. So I'm turning to this forum to see if y'all have any suggestions. My master tech friend is on a mission trip to India for another two weeks so I can't ask him.
.

 

Perhaps you should check the connections at the GEM under the dash on the driver's side. Two big connectors just above the floor, but they aren't too easy to get to. The problem on the early SD's was a leak from the windshield that allowed moisture into the connectors which caused them to corrode. I'm not sure when the windshield leak was designed out of the trucks, but my Feb. 01 truck has not leaked there. The corrosion can cause all sorts of problems with power windows, ESOF, door locks etc.

 

Update (this is the son speaking): I looked under the dash for the GEM. Didn't see anything I recognized, so I googled it and found this image (pic attached). Had another look under the dash, and I didn't see any rectangular box other than the fusebox... Is that what the GEM is? I'm guessing it's not the PCM...
Oh and the power locks work now. With the Viper keyfob, and both front door switches. So that does support the theory of corroded connectors, but under the dash it all looks good, I couldn't see any corrosion.