First post here - I searched a while but couldn't find anyone with the same issue.

My van intermittently started having an issue where door locks wouldn't work. When I would press any door lock button in the car they would do nothing - not even a hint of noise. Almost like the battery to the car had been disconnected.

This would come and go. Sometimes they'd begin working after driving a few minutes. Othertimes a whole day. Finally a few months ago they didn't work for weeks on end, completely dead. After disconnecting/reconnecting all the controls at each door they began working again. They were fine for a few months until a few days ago. Now they are back to intermittent.

I believe I've read the passenger switch is the 'master'? Is it possible it's just going bad or is there a potential other source of issues I should investigate?

 

When they seem dead, can you lean over and operate the door lock switch on the passenger door? That might be enough to point to a worn out switch. The wiring for the locks leaves the door in that ribbed rubber boot at the front of the door. It gets flexed on every entry/exit and a wire could be broken. Time for a Multi-meter and door panel/kick panel removal. What year is this van?

 

When this happens all three switches are dead simulatenously.

 

Locks have been dead for a couple weeks. This morning though the lock button on the eat door works but both front ones are dead. Any thoughts?

 

check the grounds first
do you have a wiring diagram ?

 

Well I did some troubleshooting. It seems if I disconnect and reconnect the driver switch everything starts working again for a while. I think 5he switch is failing so I ordered a replacement.

 

Good

 

I believe the problem is now moisture related. After replacing switch I still have troubles. It seesm on wet days first thing in the morning locks work, but after driving i have truoble. The rear lock switch seems to always work. After spending 12 days in a dry climate (haven't had more than 24 horus of dry weather in portland in months) I found my locks worked 100% reliably for the whole 12 days, including a 3,000 mile round trip.

I have looked around for where moisture might be getting on wiring, but have come up empty. Any thoughts on common problem areas for moisture?

 

the "accordion" from the body to the door?

 

My 2007 E350 did not have power locks, so I ordered a kit off ebay for about $30 and installed it. Works like a charm, but the reason I tell you this is that there is not much to this that could go wrong other than the switch or the acutator that pushes the lock up and down.

If those are working, it has to be in the wiring. The way the switch works is you have a power and ground. When you push the switch one way, the polarity is in one direction which is up or down, when you push the switch in the other direction, the polarity simply reverses and the window goes in the opposite direction. If you replaced the switch, most likely you have something shorting out or a bad connection somewhere in the system.

I would start in the door and work your way back. As someone else has suggested, maybe inside the rubber boot between the door and chassis, or even at one of the actuators itself? But having just installed one of these, if you have ruled out the switch and the actuators, I'm guessing most likely a wiring issue.