A little clarification

Rudy Technician Montebello, California Posted   Latest   Edited  
Question
Electrical
2012 Honda Civic Si 2.4L (K24Z7) 6-spd (SY1M)

I have 2 questions. 

  1. Am I correct in thinking the drivers window switch works independently of the window relay?
  2. Does the MCU ground the window relay at all times with key on or in run?

Edit: Im sorry if the diagram is too small to read, it is the vehicle in the title if you wish to help and look in your own SI(its a 4 door)

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James Owner/Technician
Pike, Pennsylvania
James Default
   

The way I read it is if it has auto power window it is independent of the relay otherwise without the auto feature it is powered through the relay. As far as when the MCU grounds the relay, I don't think there is enough info there to say, but my guess would be yes when the key is on and in run positions. What gets me is that It looks like the auto window would work all the time on the driver's…

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Rudy Technician
Montebello, California
Rudy Default
 

James- How did you come to that conclusion regarding the drivers switch? It looks to me like pin 15 is straight fused power. Also the way I read the MCU is that I dont see any actuation(switched input) in the diagram for the relay. So it looks to me like the relay is grounded(actuated) once the key is on, but like you Im not 100% on that.

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Willie Mobile Technician
Little Rock, Arkansas
Willie Default
 

1. Probably not, that window switch has an input from that relay also. 2. Probably not also, think about it, that relay being energized with the key off at all times.

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Rudy Technician
Montebello, California
Rudy Default
 

Willie- Which pin on the drivers switch is an input from the relay? I didnt asked if the relay was energized key off. I asked if it was energized with key on. (and no other input other than the key being on)

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Willie Mobile Technician
Little Rock, Arkansas
Willie Default
   

Missed question #2. Pin 26 and fuse B44. Yes the relay would be grounded with key on or in run, and accessory if it has one. By it being mcu controlled the OEM can stop the windows from working anytime they want, like if some replaced the module without programming.

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Tom Mobile Technician
Chicago, Illinois
Tom Default
 

Fuse 42 is for the Driver's window. MCU grounds the relay with key on. Reason for that is so the windows can still be operated for up to 10 minutes with key off or until a door is opened.

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Scott Owner/Technician
Windsor, New York
Scott Default
 

1. If the drivers window switch worked independently of the relay, then the drivers window would be operational at all times, and since that's not the case, the answer would have to be no. The input from the relay comes from fuse B44. 2. Difficult to tell from the wiring diagram, but it would make sense that anytime the key is on the MICU would ground the relay so that the windows will be…

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James Owner/Technician
Pike, Pennsylvania
James Default
   

I was looking at a schematic from Alldata which shows the ground being controlled by the MCU but looking at your diagram there is no proof of that and fuse 42 which feeds the driver's window shows hot at all times and the feed at pin 26 must somehow control the on off time of the master

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Clinton Diagnostician
Concord, California
Clinton Default
 

I agree with everything James Allen Smith says from his first comment to the last.

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Rudy Technician
Montebello, California
Rudy Default
 

Ok guys, so the consensus to question 1 seems to be that fuse B44 to pin 26 is the relay input for the drivers switch. Id like to know how you came to that conclusion? Also do you think pin 15 of the drivers switch is simply B+ for the control unit?

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Eric Owner/Technician
Edgerton, Wisconsin
Eric Default
 

I do not believe the driver's power window switch works independently of the power window relay. Power for the driver's power window switch comes from pin #26. I do not know if the switch has actual battery power flowing through it, you would have to make measurements at the switch, or if the control unit just uses the switch as a signal input using a lower voltage signal, like a 5 volt…

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Clinton Diagnostician
Concord, California
Clinton Default
   

My thought process is this, pin 26 of the pwms is being fed by a 20amp fuse on the switch Side of the pw relay which would mean that the micu controls that voltage by energizing the coil side of the relay. I also considered that in order for the windows to continue to operate in the key off position, there needs to be voltage supplied to the switch. There’s 2 ways I can see this happening…

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Rudy Technician
Montebello, California
Rudy Update
   

In regards to question 2. After some more digging,I found a some pin out values in the service info. According to the info pins 20, 21 and 26 should have battery voltage key on or in run. This verifies that the window relay is on at all times with the vehicle on. Still unsure about question 1. (your guys answers are all over the place. Glad to see it wasn't just me who was somewhat unsure of…

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Sherman Service Manager
Tucker, Georgia
Sherman Default
 

Hi Rudy, It seems that the Micu does control the power window relay, but the driver side window switch is independent of the relay using pin #15 input fuse #42 20A if the vehicle is equip with auto power window. If it is not equip with power window it will get its power from fuse # 44 20A. The wiring harness is wired for both options w/Auto power window or w/o power window ! that’s how I see it…

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Brian Owner/Technician
Charlottetown, Prince Edward Island
Brian Default
 

Rudy , I think the white B+ wire in terminal 15 serves 2 purposes .1 To provide power for KAM in the control unit otherwise you would probably have to reinitialize the windows every time and 2 to provide power for the door locks to be able to work via the remote . The window switches cannot work without the relay being powered up by the key on signal to the micu or unless the timer function is…

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Stephen Technician
Gallatin, Tennessee
Stephen Default
 

What does the REMOTE- LOCK/UNLOCK switch do?

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Rudy Technician
Montebello, California
Rudy Default
 

Stephen- Im not sure. Couldnt find mention of it anywhere in the system description.

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Stephen Technician
Gallatin, Tennessee
Stephen Default
 

I was wondering why the driver switch had full time and switched battery inputs? With diode coupling? So I wondered if the REMOTE (what does remote mean?) LOCK/UNLOCK could cause the MCU to turn off the window relay? But, if the driver window IS supplied by full time battery, it would work with the key off and there would be no reason to supply it with switched battery as the full time would…

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James Owner/Technician
Pike, Pennsylvania
James Default
 

If I understand your question, my take is it's just that the switch to lock and unlock the doors

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Caleb Diagnostician
Mishawaka, Indiana
Caleb Default
 

Hey Rudy. To answer question 1. Pull fuse B44. If the drivers window stops working then you have the answer to your question. See the little bus bar inside the drivers window switch that goes over to the drivers window MICU from pin 26?

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Rudy Technician
Montebello, California
Rudy Delay
 

There was no clear answer for question 1. Question 2 was confirmed. Thank you for your participation.

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Caleb Diagnostician
Mishawaka, Indiana
Caleb Default
 

Did you try what I suggested for #1 Rudy?

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Rudy Technician
Montebello, California
Rudy Default
 

Caleb- Sorry, I ment to do that. Ill do it later today and report back.

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Rudy Technician
Montebello, California
Rudy Resolution
   

Just to wrap this up. Caleb (and a few other guys)were correct. I removed fuse B44 and both front windows stopped working. That seems to indicate there is indeed a bus bar leading into the drivers control unit and the drivers window does not work independent of the window relay.

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Caleb Diagnostician
Mishawaka, Indiana
Caleb Default
 

Nice gtk. Thanks for the follow up!

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