Technical windshield wiper never stops ducato 2021

[shortan]

Hello everybody,

I have a problem with my 2021 DUCATO, the windshield wipers never stop. as soon as I turn on the ignition, they start up, even if I remove fuse F43
I have error B1020-12, wiper motor control, short circuit to +v
I tried cleaning the contacts on the switch side but it didn't work.
I also specify that the windshield wipers start at speed 1 regardless of the position of the switch except when it is in fast speed, the windshield wipers go to speed 2 (which could seem logical if they did not start it even when the switch is off)
I also specify, if I disconnect the steering column switch, the windshield wipers work at speed 1 all the time

Do you have any idea for this problem?

Thank you for reading me

 

[bugsymike]

Hello everybody,

I have a problem with my 2021 DUCATO, the windshield wipers never stop. as soon as I turn on the ignition, they start up, even if I remove fuse F43
I have error B1020-12, wiper motor control, short circuit to +v
I tried cleaning the contacts on the switch side but it didn't work.
I also specify that the windshield wipers start at speed 1 regardless of the position of the switch except when it is in fast speed, the windshield wipers go to speed 2 (which could seem logical if they did not start it even when the switch is off)
I also specify, if I disconnect the steering column switch, the windshield wipers work at speed 1 all the time

Do you have any idea for this problem?

Thank you for reading me

The only things that spring to mind to me are a faulty wiper relay contacts stuck together at the fuse box and wiper motor it's self a fault in the "Self Parking" side, this used to be more common in the old days.
As you say pulling the plug on the wiper switch doesn't stop the problem so more involved. Maybe a good auto electrician can trace the fault.
Have you tried a good diagnostic tool to read any errors stored?

 

[shortan]

thanks for your answer.
I spent the day on it today, I'm going crazy.
I use multiecuscan to read the errors, that's where I have the error B1020-12.
Here is what I did as a test:
- I tested with multiecuscan the function of the commodo, it detects all the states of the switch (stopped, speed 1, speed 2, intermittent). I did not check the resistance on the pin side of the commodo but I tell myself that if it detects well on multiecuscan, it must be good
- I tested the continuity of the cables that go from the body computer to the windshield wiper motor, they are ok.
- I checked the relay on the fuse box side, it's ok, I swapped it with another one and it gives the same problem
- on the wiper pin side, I have +12v on pin 2, ground on pin 1, speed 1 or 2 on pin 3, and the engine position feedback on pin 5. On pin 4 which corresponds to the engine start/stop, I never have any voltage, as if the switch was always on. Without the contact, the wire is not grounded, it becomes so when the contact is made
I'm almost wondering if it's not the body computer that is faulty.

I haven't checked the internal relay in the engine and for that I'm afraid it's beyond my skills.

What do you think of this problem? body computer or relay in the engine or something else?

sorry for my English (google translate), hope it's at least a little clear

 

[bugsymike]

thanks for your answer.
I spent the day on it today, I'm going crazy.
I use multiecuscan to read the errors, that's where I have the error B1020-12.
Here is what I did as a test:
- I tested with multiecuscan the function of the commodo, it detects all the states of the switch (stopped, speed 1, speed 2, intermittent). I did not check the resistance on the pin side of the commodo but I tell myself that if it detects well on multiecuscan, it must be good
- I tested the continuity of the cables that go from the body computer to the windshield wiper motor, they are ok.
- I checked the relay on the fuse box side, it's ok, I swapped it with another one and it gives the same problem
- on the wiper pin side, I have +12v on pin 2, ground on pin 1, speed 1 or 2 on pin 3, and the engine position feedback on pin 5. On pin 4 which corresponds to the engine start/stop, I never have any voltage, as if the switch was always on. Without the contact, the wire is not grounded, it becomes so when the contact is made
I'm almost wondering if it's not the body computer that is faulty.

I haven't checked the internal relay in the engine and for that I'm afraid it's beyond my skills.

What do you think of this problem? body computer or relay in the engine or something else?

sorry for my English (google translate), hope it's at least a little clear

The "error B1020-12." is possible Can Bus Error code, as I understand it most electrical stuff on modern vehicles is controlled by low voltage signals along "Can Bus Wiring" which is often a "twisted pair" of wires which if badly repaired or get a signal from another wire can give all sorts of problems.
So unless you know of a dodgy repair in that area I would let the "professionals" have a look.
I assume no corrosion or water damage yo wiring or plug sockets at BCM etc?
By the way though not perfect your English is better than my French, mine was enough to order a double bedroom and a bottle of wine in late 70s, that was all that I needed at that point

 

[shortan]

That's what I'm doing but I wish I could find something before I take it to the garage because I'm afraid he'll just change part by part until he finds the right one.

By the way though not perfect your English is better than my French, mine was enough to order a double bedroom and a bottle of wine in late 70s, that was all that I needed at that point

that's the main thing, as long as you manage to make yourself understood for that

 

[Anthony489]

Hi Shortan

I only have schematics for earlier vehicles (2006 onward) but maybe yours is similar ? Attached is a schematic for the vehicle, and another one drawn by me to show what is inside the wiper motor.

The stalk switch tells the Body Control Module (BCM) what to do. I think your switch is OK.

The wiper motor gets +12 volts on Pin 2, via relay T12 and Fuse F43 (30 Amps). Ground is on pin 1.

There are two "logic" control inputs driven by the BCM, Pin 4 is grounded to run and +12 volts to stop. Pin 3 is grounded for High speed and +12 volts for Low speed.

There is one "logic" control output back to the BCM, Pin 5 is Open Circuit when the blades are sweeping the screen, and Ground when they are parked.

Wiper motors take quite a high current to run. It is unusual that the wipers still run with Fuse F43 removed, unless you have a short-circuit to +12 volts in the wiring. Check again that you have removed the correct fuse.

The next step for you (or your auto electrician !) is to connect thin extension wires to the 5 connections of the wiper motor and check all the voltages relative to a separate ground whilst it is running. Fold the blades out to avoid high friction on a dry screen.

Bonne Chance !

 

[shortan]

Hello Anthony489,

Thanks for your explanations.
Fuse f43 seems to be used only for the windshield washer, there is another fuse and a relay in the fuse box on the engine side and if I remove them, the windshield wiper motor no longer works.

The problem I have after the tests carried out and that pin 4 is systematically grounded, this is probably why the engine runs all the time. No matter the position of the switch, there is never 12v. For the other pins, they have the behavior you describe. (including 12v for low speed on pin 3 and 0 or about +12 for pin 5)
Concerning pin 4, I did a continuity test of the wire, it is not cut, it goes well to the body computer and also it is not connected to ground. From there, if the body computer never sends the 12v, I don't see what it could come from except maybe a bad contact on the BC pin.

I'm going to take it to Fiat but I feel like I'm going to have to change the body computer especially since I found an article on the net where there seems to be an epidemic on this part on Ducatos of the same generation as mine (https://www.routard.com/forums/t/epidemie-sur-les-body-computers-de-fiat-ducato-3/290317)

 

[bugsymike]

What @Anthony489 has posted should help your garage with any luck.

 

[shortan]

Thank you, I will keep you informed of the breakdown when we have found the reason.

 

[shortan]

Hello,

As promised, after spending a lot of time in the garage testing the switchgear, wiper motor, wiring harnesses, and more, the problem lies with the body computer. After replacing it, everything is working properly again.

Maybe this can help others in my situation.