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Bosch Washing Machine WFMC6400UC/01 Door Lock Problem

BOSCH Washing Machine WFMC6400UC/01 Door Lock Analog Pressure Sensor

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19 replies to this topic

#1 DrAV

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Posted 11 April 2013 - 01:37 PM

Here is my tale:

 

Our Bosch Washer failed at the end of the wash cycle with the door failing to open.   The door lock now makes a buzzing sound when the machine tries to lock or unlock the door.  It did not buzz before this failure occurred.   When the machine tries to unlock the door the door lock will buzz three times in a row then pause for a bit then buzz three times in a row and continue...

 

The door manual release did not work.  Eventually we were able to get the door open by pulling on the door when the machine buzzed the door lock.   Now we had access and removed and disassembled the lock.   It was actually quite easy to take apart and put back together.  The solenoid return/centering spring had broken it two possibly jamming the manual lock release.  Everything else looked fine.   I was able to repair it by stretching one of the longer remaining spring halves and reinstalling all the parts.  It all appeared to work perfectly after reassembly including the manual release.  I reinstalled the lock and the problem continued.

 

We can run the machine and everything works fine except for this issue.  We are opening the door with the manual release cord.   I then ordered a new door lock and replaced the door lock and the problem continues.   I replaced the control module and the problem continues!

 

I obtained the service manual for this model.   I checked the wiring between the door lock and the control module with a DVM and it is fine with good continuity.    I checked the door lock switching with a DVM and the coil.   The switches are working fine and the coil measures 120 Ohms between the outer terminals and about 60 ohms between each outer terminal to each inner terminal.  I checked the drain pump and cleaned it out (removed two plastic pieces from a child’s ruler that had found their way to the pump).   The pump seems fine, looks fine, and pumps fine.   The problem continues!

 

I have run the service fault code menu several times.   Mostly ER04 comes up (the service manual indicates “Door Lock Triac or Control Module Failure”).   The Triacs on both control modules (Original and replacement) look fine with no burns, burned parts, or visible board damage.   Sometimes ER01 door lock comes up.    When running the machine during a wash sometimes it displays on the main panel after it tries to lock or unlock the door  “Door Can’t Be Locked” or “Door Can’t be Unlocked” (I can’t remember which it is at this time… I didn’t write it down.   Sometimes it just says “Error”.

 

Once during running the service fault menu test it came up with ER015 “Pressure Sensor Gives Failure Voltage Level”.    This only has shown up once.    I think I read a post on anther Bosch Washer Model that the Analog Pressure Sensor failure can appear as a “Door Lock” problem.   Anyone with ideas or thoughts on what is really wrong?   Is it the pressure sensor that is causing the problem?



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#2 Samurai Appliance Repair Man

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Posted 11 April 2013 - 04:52 PM

To summarize:

 

- door stayed locked closed

 

- you replaced the both the door lock and the control board

 

- problem continues

 

What are the part numbers of the control board and door lock that you replaced?



#3 DrAV

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Posted 11 April 2013 - 06:07 PM

Yes the summary is correct.   Here are the part numbers (the parts looked and installed identically, except the control board plastic case was black on the new module (original was beige/clear)  and the back light in the new LCD panel was orange instead of the original red color.)

 

Door Lock: 497391

Control Module Board: 436437



#4 DrAV

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Posted 11 April 2013 - 06:12 PM

 Oh,

 

I almost forgot... Konnichiwa.



#5 Samurai Appliance Repair Man

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Posted 11 April 2013 - 08:29 PM

I'm wondering if you got one of the bad batches of door lock assemblies out there.  Where did you buy it?

 

gallery_4_5_143267.png

 

PS. Konnichiwa!  



#6 DrAV

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Posted 12 April 2013 - 11:00 AM

Appliance Parts Pros.   This has gotten me bummed a bit.  I didn't look at the door lock numbers per the diagram as I didn't have the manual yet when I installed the replacement lock.

 

Here is what I did....

Step 1: Rework Old Lock = Still Fails

Step 2: Order New Lock and Install = Failing in the exact same way as step 1

Step 3: RETURN New Door Lock

Step 4: Order and Install New Controller Board with Old Door Lock = Failing in exact same way as all the other steps.

 

I probably should have kept the new lock and tried with the new board.  Hindsight is alwasys 20-20.

 

Do you suggest that I order another door lock, verify the numbers per the diagram, and install?

 

Kanpai!



#7 Samurai Appliance Repair Man

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Posted 12 April 2013 - 11:23 AM

Appliance Parts Pros only sells new (as in unused), OEM parts but they may have had old stock (but still unused).  They use Marcone's inventory and distribution system and I have occasionally gotten out-dated parts from Marcone for my service bidness.  

 

What are the numbers on your old (present) lock and how do they compare with the image I posted for you?

 

Here's the part link for the new door lock assembly from RepairClinic.  They tend to have fresher stock because it's all maintained in-house by them-- they don't use a third-party network.  It's worth ordering and trying it; if the problem persists, return it for a refund and we'll put our heads together again.  



#8 DrAV

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Posted 12 April 2013 - 01:17 PM

The number on the end panel is 10042CN.   So it does have the N and therefore the part should be good.

 

I was just able to run the Analog Pressure Switch Test and the Manual Pressure switch test and they both ran well.

 

I guess I will order another door switch and try it with the new module.   If that doesn't work I guess I could try another new module... it's got to be one or the other.   I'm out of ideas at this point.

 

Domo Arigato for the link.



#9 Samurai Appliance Repair Man

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Posted 12 April 2013 - 01:55 PM

Two other possibilities, one less likely, the other more likely.

Less likely is that the door is torqued and actuator tab on the door is inserting and resting in the door lock receptacle with a slight torque or twist.

More likely is that the wire harness between the door lock assembly and the main control board is bad. You'd be amazed at the number of bad wire harness or wire harness connectors I find on washing machines. On some brands, it's so common that techs will actually stock the wire harness (Samsung TL washers, Whirlpool VM washers, to name just 2 examples). Disconnect and reconnect the door wire harness connector from the main board. Ohm out each wire in the door lock harness end to end.

#10 DrAV

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Posted 12 April 2013 - 02:16 PM

I checked the door a while ago.  The tab is straight and it appears to be going into the door straight.   It's going into the door a little low as in rubbing a bit on the bottom edge of the slot.  But it's minor and does not seem to be causing a problem. There is no way to adjust the door!   The fasteners have no adjustment mechanism for alignment.

 

I'm aware of wiring harness issues having worked around aircraft wiring.   I've already checked and rechecked each wire in the harness from switch connector to control module connector.  I've even wiggled the wires at each connector while doing the test to see if there is an unseen break or poor connection going into each connector.   They seem to be solid.   I've had the connectors unplugged and reconnected now many times between the module and the door lock.   One would think if this was an intermittant issue at least one time things would start to work, but no luck.

 

It may still be possible that the actual contacts inside the connectors are cruddy and not making a good contact when mated.  Not sure how to clean inside or how to obtain a new harness.



#11 Samurai Appliance Repair Man

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Posted 12 April 2013 - 02:22 PM

 

I'm aware of wiring harness issues having worked around aircraft wiring.   I've already checked and rechecked each wire in the harness from switch connector to control module connector.  I've even wiggled the wires at each connector while doing the test to see if there is an unseen break or poor connection going into each connector.   They seem to be solid.   I've had the connectors unplugged and reconnected now many times between the module and the door lock.   One would think if this was an intermittant issue at least one time things would start to work, but no luck.

 

 

Wiggling and disconnecting are not a substitute for ohming.  Just a tip from an old battle-scarred Samurai who's seen his share of weird wire harness failures.   :argh:

 

It may still be possible that the actual contacts inside the connectors are cruddy and not making a good contact when mated.  Not sure how to clean inside or how to obtain a new harness.

 

 

 

 

Can of spray contact cleaner or a dab of conductive grease could help.  Another problem with those wire harness molex connectors is the receptacles spread out and stop making good contact and pins tend to recede in the connector, again interrupting contact.



#12 DrAV

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Posted 12 April 2013 - 02:53 PM

Just checked again for laughs.  I disconnected from the main controller board and left the door lock unit attached and checked witha  DVM at the Controller Board connector.  At the Controller Board connector I can see that the door switch and lock switch are working perfectly and I can see the same solinoid resistance that i see when i measure at the door lock.... 120 Ohms from outter pins and 60 ohms from the outter pins to the inner pin.   On another post somewhere else, someone else reported the same solinoid resitance on the door lock that I'm seeing when they checked it (just added this because it does not agree with their wiring diagram from the service manual that indicates 159 to 211 ohms across the outer pins).

 

The connector on the Controller board end of the wire harness does not appear to be a Molex.   It appears to be a better design with U shaped contacts that rub on each side of the controller board contact spades as it goes in.  Nothing to push in and plenty of area to made good contact.

 

Thanks for the  tip on the cleaning. My can of electrical ccontact cleaner degreaser is empty.  I'll pick some up later today and give it a shot... pun intended.

 

Konpai



#13 DrAV

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Posted 22 April 2013 - 05:27 PM

OK problem is now solved. I installed the new door lock switch and auto-magically it worked! The door lock works as it should with a solid thunk and no buzzing. Next I tried the switch with the Old Controller board and sure enough it worked also. So I am left wondering why the first replacement door lock didn’t work. The first door lock that I ordered looked identical to the second replacement door lock. Both were obviously a newer design, different colors than the original, and different redesigned door release pull cord and attachment.<br /><br />So my thoughts are this… My attempt to fix the old door lock while it looked functional and seemed functional was probably not engaging the door lock switch contact properly. This was likely due to my trying to reuse the remaining spring material in place of the original spring. The tip off was that it appeared that when the door lock was in the unlocked position, the mechanical lock seemed to still be slightly engaged requiring the manual door lock release to open the door. I also tested my first replacement door lock connected into the harness but not installed and likely the switch was not in the proper configuration (the door lock and the door open-shut switches must be in the right state (Open-Open or Closed-Closed and not Open-Closed or Closed-Open). The only other alternative is that the first lock switch was indeed defective.<br /><br />Note: I checked the solenoid resistance on the new door lock and it matches my old “broken” door lock solenoid resistance. 120 Ohms from the outer contacts and 60 ohms to the inner contact. So the documentation in the Bosch Service Manual is wrong on the solenoid resistance measurement. Finally, the problem was never related to the solenoid but to the stupid broken spring in the door lock. A 10 cent part requiring the replacement of a $60 door lock assembly. Live and learn.<br /><br />Biiru Kudasai? Kanpai!<br />

#14 Samurai Appliance Repair Man

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Posted 22 April 2013 - 05:32 PM

Thanks for the followup report!  

 

Did you happen to take any photos of the spring you're referring to?



#15 DrAV

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Posted 22 April 2013 - 06:02 PM

I still have the the broken door lock and can take it apart and take a picure or two and post. Maybe later today or tomorrow. If I was really industrious I probably could have tried to match a replacement spring at ACE hardware. 

 

I should note the following lessons learned with replacing the control module. The cycle selector dial can be accidently installed 180 degrees out on this machine (bad design Bosch). Ask me how I know... There are no identification marks or documenation on this. Make sure you turn the machine to OFF then tape the selector dial in the OFF position before you remove the controller board/housing. The selector dial stays with the top panel when you remove the controller/board housing. When you install the new controller board/housing first make sure that the engagement tabs in the new cycle selector switch are lined up at the same position as the controller board cycle switch you just took out. There are 3 tiny tabs at the 9, 12, and 3 O'Clock positions. (You'll understand these directions once you have one of these apart and look at the cycle switch and slector dial.) 

 

The control module is a bit difficult to take off and requires some patience. The hard part is disengaging three (3) internal plastic locks on the left side of the housing through 3 small holes in the housing while at the same time disengaging the plastic locking tabs on the outside of the module at the same time as applying some lifting pressure. Four hands or more are required for this operation. :woot:
 


Edited by DrAV, 23 April 2013 - 12:58 AM.


#16 DrAV

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Posted 22 April 2013 - 06:36 PM

Post deleted.


Edited by DrAV, 23 April 2013 - 12:59 AM.


#17 Samurai Appliance Repair Man

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Posted 22 April 2013 - 06:36 PM

<p></p>

 

 

How are all the HTML tags getting into your posts?



#18 DrAV

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Posted 23 April 2013 - 01:00 AM

Crappy Outdated Internet Exploder at work.  Now at home working on Firefox.   I'll post images as soon as I figure that out...



#19 DrAV

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Posted 23 April 2013 - 09:18 AM

I'm attaching pictures as files since I am having an issue pasting them and having them show up directly.

 

Door Lock 1:  Picture of the lock disasembled with the lock mechanism in the closed position.

Door Lock 2: Close up

Door Lock 3: Close up with the door lock switch contacts and locking mechasim in the open position

Door Lock 4: A veiw of the spring with other parts removed.  The spring sits in a slot in the back of the door lock latch and serves to return it to the closed position.  The orginal spring broke in two and I stretched the larger part and reinstalled it as picured here.   The spring sits in two tiny black plastic pivoting caps.

 

 

Attached Files


Edited by DrAV, 23 April 2013 - 10:05 PM.


#20 RegUS_PatOff

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Posted 23 April 2013 - 10:00 AM

If posting to this website, 200k file size limit,

OR

post to a a file hosting site, then post links here


.

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every day is Down Syndrome Awareness Day
"A Child Is Waiting" . Burt Lancaster . Judy Garland . 1962

RegUS_PatOff > www.youtube.com/watch?v=oPAY2LsKVEw





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