Windshield Wipers 2010 Expedition - all work or none work

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Stang8650

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Hi all and thanks in advanced for any help. I'll try to make this as short as possible (but that's going to be hard...)

My wipers all work (Front wipers, front windshield spray pump, rear wipers, rear spray pump) and then other times nothing works. I'm pretty sure this is related to a safety input signal that is either telling the BCM (if these have a BCM?) that it's good to allow the wipers to work or it's not safe to operate them. I've checked all (4) fuses and the main relay for wipers and all is good there - plus sometimes they all work which wouldn't be the case if I had a blown fuse or bad relay. I've even swapped relays with known good ones just to make sure.

Back story - I recently had the rear hatch and hood painted due to the crappy aluminum prep/paint bubbling that I'm sure many of you have dealt with. The hood was removed for paint/prep and the hatch was left on the vehicle for paint/prep (but the rear wiper assembly was removed for paint). I get the Expedition back, it looks great! Except I don't have wipers when I try to run the front wiper fluid spray on my way home. I call the shop and ask if they remember unplugging anything, they don't. I don't see any obvious plugs undone under the hood.

Hint #1 - when I double click the lock button on the key fob, it should just beep the horn once. It's beeping the horn twice, so I know it will do that if a door, the rear hatch, or rear hatch glass isn't closed when you try to double click the lock button. I check all those areas - they're all closed. I think about it for a bit, pop the hood and manually hold down the hood closed switch. Now I get one beep of the horn from the fob - I know the hood closed switch wasn't pushed down enough. I bend up the bracket, close the hood. Everything's happy and the wipers are all now working! (I've read this is a safety feature - the wipers are all told not to work if the hood is up). I think I'm home free and I'm pretty proud of my troubleshooting skills on that one.

Next night, it's raining. I turn on my wipers and NOTHING again! I get home, use electrical tape to tape the hood switch down (so it's always closed). I confirm with Ohmeter that the switch is a closed circuit now. Wipers all work again. I'm again impressed with my skills.

Next day - wipers work on some startups, wipers don't work on other startups. I know the switch is taped closed, but maybe the switch has a finicky spot in it? I read that a faulty hood switch can cause some alarms to go off in the middle of the night. Maybe hood switches go bad? For $35 it's worth buying a new one. I buy a factory Ford switch, put it in. Wipers work!

Next day - no wipers work on startup. Now I'm getting mad.

I've figured this out now to the point that if the wipers don't work. Turn the car off and restart the car, most of the time they work on the second start. Weather in the Northeast sucks, it's raining again today. It took 3 starts to get into a mode where the wipers work. They worked fine for my half hour drive to work today.

I'm convinced at this point where ever the hood closed switch signal goes to (body control module), it's sometimes happy with the signal and it tells the wipers all work (front, rear, etc.) and other times it doesn't like the signal and it tells everything to not work. Is there a Ford Tech out there or someone who's had a similar problem?? Can a Ford Tech with a real scanner hook up to the vehicle and find what the faulty signal is on the 1 out of 3 startups when the wipers are told not to work?? Please help, I'm regretting putting $ 1,500 into this vehicle to get the paint looking good again. It's a great vehicle and in great shape which is why I'm trying to keep it rather than sell and buy something newer. Thanks again for any help!
 
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Stang8650

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An update on this since I know it's keeping everyone up at night.

I think I've proved the hood switch isn't causing this issue. When the wipers weren't working, I see 14 volts (with car running) for supply voltage to the hood switch - then when they are working I see this same voltage here. So supply voltage to sensor is present at all times (and new Ford sensor too that I know is working with the Ohm reader).

Out of curiousity I popped the hood when the wipers were working with the car running - the wipers kept working. Then I unplugged the sensor - wipers still worked. Then I left the sensor unplugged and cycled the ignition - the wipers still worked. So I think this was a coincidence that I noticed the hood switch wasn't pushed down enough when I heard that two beeps the first day when locking the vehicle and this is independent of my current wiper issue. I guess the hood switch isn't used as a safety for the wipers to work or not - they're allowed to function as normal with the hood up.

So now I'm more confused than before. I think the next obvious thing to do is take the trim off the rear hatch and make sure I don't see a wire back there that's maybe shorting sometimes since I know that assembly was removed when painting the hatch - but would that really affect the front wipers too? What would be another cause that sometimes the wipers all work fine, and on other starts EVERYTHING is dead (front, rear, etc...) really weird. Multi-function lever on the steering wheel? I would think that would be intermittent while the car is running though too? On the starts the wipers work, they continue to work even if I turn them on/off. On the starts the wipers don't work - they'll never come to life on that start, I always have to turn the car off and back on to get them to work.

Any suggestions on what to look at or someone with experience with an issue like this is very much appreciated. Thank you.
 
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