Greetings!

I did a quick keyword search to see if there were any posts or threads that deal with what I'm about to describe, but I didn't see anything useful. Here's the scoop:

Sunday I took a leisurely drive in my 2015 F-350 and was annoyed to find that my wipers would not shut all the way off. I checked the fuses relating to the steering column and the wiper motor, which were both intact. "No biggie" thought I, "I'll figure this out later in the week."

Fast forward to Wednesday, I went to start the truck up and it wouldn't turn over. It behaved like the batteries weren't quite up to snuff. I thought that was weird, and maybe the malfunctioning wiper switch was draining current from the batteries somehow. I spent the bulk of today recharging both batteries. Still won't start. I tried jumping it with my Grand Marquis. No dice.

I noticed at this point that the transmission temperature indication on the dash with the ignition on was 70 degrees colder than the indicated oil temperature. It was about 90 degrees out today. Indicated oil temp was in the upper 80s, trans temp registered at 18 degrees.

I changed the fuel filters in case the engine not started was the result of a blockage or water in the lines. No water in the diesel, and no startup with new fuel filters.

I spent the last three hours crawling around under the truck, in the engine bay, and in the wheel wells looking for broken or chewed wires. I found an old mouse nest behind the passenger side fog light, but no obviously broken or damaged wires there or anywhere else. I've especially paid attention to the wiring around the starter and the transmission temperature sensor.

So... anybody got any ideas? To sum up the issues:
-Wipers won't turn all the way off
-Engine won't turn over, even when jumped
-Indicated transmission temperature is way too low

Thanks all.

 

I had a 2016, and I know there were issues with bad steering column stalks. Wipers would start on their own. I’m not sure how the switches are integrated into the trucks networked systems but I suppose it’s possible it’s causing other issues.

 

Thanks Dave. I should mention that the wiper issue has been intermittent today the many times I've turned the key to ignition position.

 

Well you make think this is nutty suggestion but make sure that the hood is shut properly or it could be the switch on the hood latch. I had read that could be an issue with those symptoms. Just a suggestion.

 

Hey, at this point I'll try anything. I'll change the multifunction switch and check the hood latch tomorrow and let you know how things go. In the meantime, let's keep the speculation going folks!

 

I can’t say I’ve had any wiper or starting issues, but I have had my transmission temp read 18 degrees with key on engine off. It always has corrected once started. Not very helpful I know but I suppose it is a data point.

Maybe check the harness by the parking brake. Give it a good wiggle.

 

Thanks. That actually is helpful. I won't obsess over that data point.

Wiggling the harness by the parking brake has solved almost every other electrical gremlin I've had with this vehicle. Sadly this issue is immune to the easy button fix.

 

The new multifunction switch is installed, and while the wipers seem to be behaving themselves, unfortunately the truck still won't jump start. Any other suggestions are greatly appreciated.

 

I’d be checking all of the ground points and the battery cables themselves if you haven’t already

 

Finally got it started. It's probably apparent, but I'm very much an amateur when it comes to automotive stuff in general. My rookie mistake in this instance was not disconnecting a battery in order to check their voltage individually. The secondary battery read about 11.5 volts. Primary battery was about 6 and not taking a charge. Between them, there must not have been enough power to augment the jumping process when hooked up to the batteries of my other vehicles.

So my guess is that the faulty multifunction switch created some sort of current drain on a set of batteries that were past their prime (5 years old), and once those batteries were drained below a certain threshold, there was no recovering their previous functionality. Next time I will jump both batteries. The transmission temperature indicated on the dash becomes accurate once you fire up the engine.

I'll check back in if any of the problems surface again, but for now everything seems to be solved by new batteries and a new multifunction switch. Many thanks to everyone who offered thoughts and suggestions.

 

Nice. Glad you’ve got it figured out

 

That’s one thing you won’t forget 😁
There are battery and charging system testers that do a good job for $30, I have one from Kingbolen.