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Okay, I am sitting in my car sipping on a monster and suddenly my windshield wipers turn on on their own, Also switches from low speed to full power on its own. I know its friday the 13th but come on.. Has anyone had this happen to them. Its 2013 Focus ST with 38k miles. I have temporarily pulled the fuse. I'm over the 36k mile warranty so should i even bother with the dealer or just take it to my friendly mechanic down the street. I'm thinking it probably the windshield wiper module that went bad but any input would be great. Thanks!
 

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Verry odd indeed. If you are nearby an autozone store, they can read the OBD for free, take it from there. (plug the fuse back-in for test).

Is it a one-time glitch, or full gone-bad?
 

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Verry odd indeed. If you are nearby an autozone store, they can read the OBD for free, take it from there. (plug the fuse back-in for test).

Is it a one-time glitch, or full gone-bad?
Well I turned the car on and off multiple times to see if it would stop and it didn't, so I pulled the fuse until I get home and try disconnecting the battery for a couple minutes to see if that does anything.
 

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I don't know if your friendly neighborhood mechanic is going to be able to fix that as it's a rather complicated system. Then again, the typical tech at a Ford dealer might not be any better. At least the dealer has access to the wiring diagrams and the tech hotline so I'd give them a marginally better chance.

The wiper switch is part of the steering angle sensor module (SASM). When you turn on the switch the SASM sends a message over a LIN communication network (LIN1) to the Body Control Module (BCM). The BCM then sends a message over a seperate LIN communication network (LIN8) to the driver's side wiper motor. The driver's motor then uses a dedicated comm line between it and the passenger's side motor to coordinate wiper actuation and avoid the wipers hitting each other. The guy with a test light down the street might not be equipped to figure this one out.

I will, however, give you a hint. When there is a failure on the LIN8 network, the wipers will operate for 5 min on high, 5 min on low, 5 min on intermittent,then shut off. This might be what's happening with your car. This means there is most likely a wiring problem between the BCM and driver's wiper motor.
 

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The wiper switch is part of the steering angle sensor module (SASM). When you turn on the switch the SASM sends a message over a LIN communication network (LIN1) to the Body Control Module (BCM). The BCM then sends a message over a seperate LIN communication network (LIN8) to the driver's side wiper motor. The driver's motor then uses a dedicated comm line between it and the passenger's side motor to coordinate wiper actuation and avoid the wipers hitting each other. The guy with a test light down the street might not be equipped to figure this one out.

I will, however, give you a hint. When there is a failure on the LIN8 network, the wipers will operate for 5 min on high, 5 min on low, 5 min on intermittent,then shut off. This might be what's happening with your car. This means there is most likely a wiring problem between the BCM and driver's wiper motor.
The sweetness of technology................networks and modules controlling of all things......wipers......
 

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Hello,

I have a 2013 Ford Focus, and started having a similar issue a few months ago. The wipers went on full speed once I turned the car on and wouldn't shut off even by switching off the ignition. Reading I little on this forum (specifically on this post) and other places I figured that a common temporary fix was to remove a fuse from the Battery Junction Box, located on the engine compartment. Fuse was No.18, and is the one that routes the power from the battery to the windshield wiper motors. As some of you mentioned, after taking the fuse out, waiting a few hours and putting it back in, the problem would be gone. Only thing is that not for long. It would come back and do the same. I guessed it was a battery issue since I still had the original one and it had a leak on the negative pole. But after fixing that, it got even worse and got to the point where it would only work by itself and wouldn't recognize the signals from the windshield wiper/washer lever. After almost crashing on a rainy highway when the windshield wouldn't come on, I decided to track down the problem making use of my electrical engineering degree. This is the plausible cause and temporary solution I came up with.

First of all, I tracked down the electrical wiring diagram and schematics for the car (found one for the 2012 model, but figured, since it was form the same trim/version as mine, it would be more than useful, here's the link: OneDrive). After that, I went directly to the windshield wipers wiring diagram to see how the system worked and where the possible problem might be. Here's the picture of the relevant part of it to help me explain.
381535

A few things I noticed:
1. The fuse I was removing (F18) is the one that supplies the positive voltage to both of the motors.
2. The wiper/washer lever is not directly connected to the motors but through the Body Control Module and then to the motors
3. The Battery Monitoring Sensor was directly connected to the motors.

After seeing point 3, I thought that my battery sensor was messing up the wipers, since the wire that carries it's signal is the same that carries the motor's signals. To confirm this I went and checked any other wiring involving the Batery Monitoring Sensor (BMS) and found this:
381536

This gave me some insight into what was going on and the behavior of the wipers started to make sense. As you can see, the BMS is directly connected to the positive terminal of the battery through F22 (a fuse also located in the Battery Junction Box), even bypassing the High Current Battery Junction Box, which is the one that supplies power to the whole car, mainly, to the ignition and starter motor. So, conjured up a theory based on these observations and the fact that my BMS was visibly damaged due to the leak and subsequent acid vapor spillage of the previous battery. Perhaps the BMS being damaged (possibly shorted) sent a positive signal from the battery to the motors and turned them on. The fact that this faulty signal was on the same "lane" as the original signal would explain why the original sometimes didn't work and, it's direct connection to the positive terminal of the battery, would explain why it would keep going even after switching off the ignition. I guess that, under normal conditions, the signal from the BMS and the one going to the motors can both travel trough the same wire without any issues (Ford might know a bit more than I do regarding their cars and designed it like that for a reason).

This is only a theory based on the data I have available. If I had the tools to analyze the signal going through the wire that connects the 3 components (the BMS, BCM and the motor) I could determine whether is correct or not. If someone has more experience with these issues (I'm an electrical engineer but not at all an expert on car electronics, just used my basic electronics knowledge to get to a plausible cause and solution) I would greatly appreciate the feedback.

In the meantime, based on this theory, I removed the fuse that supplies the BMS (F22) and placed back the one that supplies the motors (F18) to see if it works. This would disable the BMS and, possibly, stop messing with the motor signal (for those who are wondering over your car's performance if you do this: it monitors the battery's voltage, current and temp and tells the BCM it's general condition so it can take action regarding the Energy Management System and regulate any load that might be draining the cars battery. Generally, it's important but won't be much of a problem if you leave it out while you replace it). I did this a few hours ago and tested it right away. The motor didn't come on by it self while testing it, but, in my experience, the problem would normally show up after I was a few km's in on my trip. I'll try to update you on any changes.

If it works, this would be only a temporary fix, since you're leaving out a sensor of the car's diagnostic system and can eventually cause some (possibly minor, but I'm not completely sure) problems. I had already bought the sensor before finding this out, but it hasn't arrived yet and I had to find a solution in the meantime, since here on my country (Dominican Republic) we are on cyclone season and it's a hazard going out with faulty wipers on these conditions.

Hope this serves someone as it served me. I felt like I had to give back my findings to this community since it was here where I found the thread that led me to this theory.

flies away on his 2013 Ford Focus with (hopefully) working wipers
 

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Hello,

I have a 2013 Ford Focus, and started having a similar issue a few months ago. The wipers went on full speed once I turned the car on and wouldn't shut off even by switching off the ignition. Reading I little on this forum (specifically on this post) and other places I figured that a common temporary fix was to remove a fuse from the Battery Junction Box, located on the engine compartment. Fuse was No.18, and is the one that routes the power from the battery to the windshield wiper motors. As some of you mentioned, after taking the fuse out, waiting a few hours and putting it back in, the problem would be gone. Only thing is that not for long. It would come back and do the same. I guessed it was a battery issue since I still had the original one and it had a leak on the negative pole. But after fixing that, it got even worse and got to the point where it would only work by itself and wouldn't recognize the signals from the windshield wiper/washer lever. After almost crashing on a rainy highway when the windshield wouldn't come on, I decided to track down the problem making use of my electrical engineering degree. This is the plausible cause and temporary solution I came up with.

First of all, I tracked down the electrical wiring diagram and schematics for the car (found one for the 2012 model, but figured, since it was form the same trim/version as mine, it would be more than useful, here's the link: OneDrive). After that, I went directly to the windshield wipers wiring diagram to see how the system worked and where the possible problem might be. Here's the picture of the relevant part of it to help me explain. View attachment 381535
A few things I noticed:
1. The fuse I was removing (F18) is the one that supplies the positive voltage to both of the motors.
2. The wiper/washer lever is not directly connected to the motors but through the Body Control Module and then to the motors
3. The Battery Monitoring Sensor was directly connected to the motors.

After seeing point 3, I thought that my battery sensor was messing up the wipers, since the wire that carries it's signal is the same that carries the motor's signals. To confirm this I went and checked any other wiring involving the Batery Monitoring Sensor (BMS) and found this:
View attachment 381536
This gave me some insight into what was going on and the behavior of the wipers started to make sense. As you can see, the BMS is directly connected to the positive terminal of the battery through F22 (a fuse also located in the Battery Junction Box), even bypassing the High Current Battery Junction Box, which is the one that supplies power to the whole car, mainly, to the ignition and starter motor. So, conjured up a theory based on these observations and the fact that my BMS was visibly damaged due to the leak and subsequent acid vapor spillage of the previous battery. Perhaps the BMS being damaged (possibly shorted) sent a positive signal from the battery to the motors and turned them on. The fact that this faulty signal was on the same "lane" as the original signal would explain why the original sometimes didn't work and, it's direct connection to the positive terminal of the battery, would explain why it would keep going even after switching off the ignition. I guess that, under normal conditions, the signal from the BMS and the one going to the motors can both travel trough the same wire without any issues (Ford might know a bit more than I do regarding their cars and designed it like that for a reason).

This is only a theory based on the data I have available. If I had the tools to analyze the signal going through the wire that connects the 3 components (the BMS, BCM and the motor) I could determine whether is correct or not. If someone has more experience with these issues (I'm an electrical engineer but not at all an expert on car electronics, just used my basic electronics knowledge to get to a plausible cause and solution) I would greatly appreciate the feedback.

In the meantime, based on this theory, I removed the fuse that supplies the BMS (F22) and placed back the one that supplies the motors (F18) to see if it works. This would disable the BMS and, possibly, stop messing with the motor signal (for those who are wondering over your car's performance if you do this: it monitors the battery's voltage, current and temp and tells the BCM it's general condition so it can take action regarding the Energy Management System and regulate any load that might be draining the cars battery. Generally, it's important but won't be much of a problem if you leave it out while you replace it). I did this a few hours ago and tested it right away. The motor didn't come on by it self while testing it, but, in my experience, the problem would normally show up after I was a few km's in on my trip. I'll try to update you on any changes.

If it works, this would be only a temporary fix, since you're leaving out a sensor of the car's diagnostic system and can eventually cause some (possibly minor, but I'm not completely sure) problems. I had already bought the sensor before finding this out, but it hasn't arrived yet and I had to find a solution in the meantime, since here on my country (Dominican Republic) we are on cyclone season and it's a hazard going out with faulty wipers on these conditions.

Hope this serves someone as it served me. I felt like I had to give back my findings to this community since it was here where I found the thread that led me to this theory.

flies away on his 2013 Ford Focus with (hopefully) working wipers
Update:

Today I traveled to my job and back home (32km) and the wipers worked fine. I even encountered some rain on the way there this morning (Thank God I figured this out yesterday, because it would've been a 'difficult' trip) and the wipers operated normally on every speed from intermitent low, all the way to high, including the 'one hit' swipe down and the washer/wiper compound. I think it proved it self to be a good temporary fix. (Before, even if I removed F18 and waited a few hours, the problem would come back just a few km's into my trip, so it's at lest a better fix then that one).

Cheers.
 

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@Jvas96 thank you for that input so far, very helpful. Keep us posted how it behaves with the new BMS and F22 installed as well.
 

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The wire that the BMS and Wipers are connected through is known a a LIN BUS. (local Interconnect network) it has been used as an inexpensive alternative to CAN.

A master / slave configuration is used. The same system is used throughout the vehicle. Head Lamps, Door Modules, etc..

"The LIN-Master uses one or more tables to start the sending and receiving to the LIN bus. These scheduling tables contain at least the relative timing, where the message sending is initiated. One LIN Frame consists of the two parts header and response. The header is always sent by the LIN Master, while the response is sent by either one dedicated LIN-Slave or the LIN master itself.

Transmitted data within the LIN is transmitted serially as eight bit data bytes with one start bit, one stop-bit, and no parity (break field does not have a start bit and stop bit). Bit rates vary within the range of 1 to 20 kbit/s. Data on the bus is divided into recessive (logical HIGH) and dominant (logical LOW). The time normal is considered by the LIN Masters stable clock source, the smallest entity is one bit time (52 µs @ 19.2 kbit/s).

Two bus states — Sleep-mode and active — are used within the LIN protocol. While data is on the bus, all LIN-nodes are requested to be in active state. After a specified timeout, the nodes enter Sleep mode and will be released back to active state by a WAKEUP frame. This frame may be sent by any node requesting activity on the bus, either the LIN Master following its internal schedule, or one of the attached LIN Slaves being activated by its internal software application. After all nodes are awakened, the Master continues to schedule the next Identifier."

The issue with disabling the BMS is that eventually other systems will become effected as it they require input from this sensor.

I experienced the very same issue on out 2013 Edge. As my wife put it "Our SUV is possessed!" The battery was a week old and not a knock off or refurbished unit. I noticed that it would be fine and randomly start back up. No amount of switch manipulation or key cycling would fix the issue. It would only stop after the vehicle would sit for awhile.

Well after gathered up my normal amount of documentation and my crew.
381545


I set off to deal with the angry spirits inside our vehicle.

Long story short it turned out that the wiper switch had begun to malfunction. This would send random commands to the BCM (Master) and in turn send the header frame to the Wipers (Slaves). With the ignition off the BCM wouldn't stop sending the command requests until the system shut itself down. This is normally a function of the BMS.

Without the system functioning other subsystems may not know how or when to gracefully shutdown. (Think shutting windows down by unplugging you PC from the wall) eventually you will have other issue arise.

Not to say that this is your problem but I would put it into the 90th percentile. (If were following occam's razor that is.)

Hope you get if figured out. If you need any more diagrams for trouble shooting please let me know.

J

*edit: do you have an DTC's? I know that the SASM is what directly interfaces with the BCM on our vehicles. If you have Forscan you could even perform a SASM calibration to check communication.
 

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I have a similar problem. My fender liner over the front right tire came lose and when I turned my wheel to make a u-turn, it got caught up on the tire and partially ripped apart. I had no choice but to rip it off so I could drive home and I put the fender in my trunk. As I proceeded to drive away, I noticed my wipers (both front and rear hatchback wiper) were on and I could not turn them off, nor could I spray fluid on either windshield via the wiper stalk control. It was like it was completely dead. Then shortly after, my battery symbol came on. I pulled into a gas station to remove the fuse controlling the front wipers, but couldn't remove the relay to control the back wiper. Shortly after the back wiper finally stopped on it's own, but 2 more weird things happened. An error message came on that said, "Hill Start Assist Not Available". What?! never seen or heard of this before. Then I noticed my volume raised up slightly on the radio. Definitely sounds like some paranormal activity going on.

I'm wondering if I did some damage to the wiring or electrical components when I ripped the fender lose. The battery indicator light has be even more puzzled because the battery is only 17 months old.

Any help is greatly appreciated.

Stephen
 

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I have a similar problem. My fender liner over the front right tire came lose and when I turned my wheel to make a u-turn, it got caught up on the tire and partially ripped apart. I had no choice but to rip it off so I could drive home and I put the fender in my trunk. As I proceeded to drive away, I noticed my wipers (both front and rear hatchback wiper) were on and I could not turn them off, nor could I spray fluid on either windshield via the wiper stalk control. It was like it was completely dead. Then shortly after, my battery symbol came on. I pulled into a gas station to remove the fuse controlling the front wipers, but couldn't remove the relay to control the back wiper. Shortly after the back wiper finally stopped on it's own, but 2 more weird things happened. An error message came on that said, "Hill Start Assist Not Available". What?! never seen or heard of this before. Then I noticed my volume raised up slightly on the radio. Definitely sounds like some paranormal activity going on.

I'm wondering if I did some damage to the wiring or electrical components when I ripped the fender lose. The battery indicator light has be even more puzzled because the battery is only 17 months old.

Any help is greatly appreciated.

Stephen
There's a lot going on in that area. You need to start by inspecting all the wires for damage. In your drivers fender well is your PCM. The battery junction box and high voltage junction box are just above the tire.
You may have a broken or shorted LIN BUS wire as well.
 
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Same thing happened to me. Turned out to be the ground wire from battery.
The BMS (battery monitoring system) sensor is on the LIN BUS network. Major cause of electrical issues.
 
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There's a lot going on in that area. You need to start by inspecting all the wires for damage. In your drivers fender well is your PCM. The battery junction box and high voltage junction box are just above the tire.
You may have a broken or shorted LIN BUS wire as well.
Thanks for taking the time to respond. I'm actually scheduled to bring my car into the dealership in the morning. God knows what they'll find, but at least I know the problem's isolated.

PS: I had the battery checked out and all is good, as well as my starter and alternator (all 3 of these tests were done at the same time via Advance Auto). Leading me to believe it's definitely a short.
 
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