Help with electric retract mirrors... - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

Harvey · 06-10-2015, 06:47 AM

My GT86 has electric retractable mirrors. There's a button next to the adjustment know which allows folding / unfolding the mirrors.

Looking at the wiring diagram you can see the third motor (in green) responsible for this (the other two motors are for vertical/horizontal adjust):

My question is: How do the endpoints work? How does the system know when to stop the fold/unfold motor. There seems to be no sign of endpoint sensors or anything? Does the ECU sense resistance (reached endpoints or any obstacle for that matter) through a current peak or something?

Thanks for some input (this is our of curiosity, I have no problem related to this)

LucidMomentum · 06-10-2015, 12:23 PM

No clue, but I'm going to guess that it's probably a motor rated for just enough force to push them in / out, but not further if it hits any serious resistance. Maybe special gearing or something.

I doubt it's a sensor though. Seems like overkill when you can do it mechanically.

KellieRahne · 06-12-2015, 11:59 AM

It might hit a limit switch that isn't annotated on the schematic. Keeping even a low torque DC motor energized can seriously damage the motor windings or cause brush burn, depending on the design of the motor.

The "black box" that the motor leads go through may be some kind of controller. A more detailed schematic would be nice.

Tcoat · 06-12-2015, 12:06 PM

Quote:

Originally Posted by KellieRahne

It might hit a limit switch that isn't annotated on the schematic. Keeping even a low torque DC motor energized can seriously damage the motor windings or cause brush burn, depending on the design of the motor.

The "black box" that the motor leads go through may be some kind of controller. A more detailed schematic would be nice.

Holy crap she knows her stuff as well!
Half the techies on the forum just developed a new crush.

LucidMomentum · 06-12-2015, 12:39 PM

Quote:

Originally Posted by Tcoat

Holy crap she knows here stuff as well!
Half the techies on the forum just developed a new crush.

Rahne can look at my P&IDs any day...

Fish · 06-13-2015, 01:40 PM

It might use the voltage readings to determine endpoints. Similar to windows with auto up and down. When it hits the end, the sudden stop causes a spike in voltage that the control unit can see. The control unit then memorizes that voltage spike and can use it to determine position of windows. My guess is the mirrors may operate the same way. Some cars use relays as well. I think our cars might also use an energized relay for the windows. I can't say for certain. It's been a really long time since I've looked at wiring diagrams for things like this.

But who knows. Every manufacturer does things differently.

06-10-2015, 06:47 AM	#1
Harvey Senior Member Join Date: May 2014 Drives: Celica 5th Gen, Tiburon 04, GT86 Location: France Posts: 135 Thanks: 2 Thanked 58 Times in 16 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	Help with electric retract mirrors... My GT86 has electric retractable mirrors. There's a button next to the adjustment know which allows folding / unfolding the mirrors. Looking at the wiring diagram you can see the third motor (in green) responsible for this (the other two motors are for vertical/horizontal adjust): My question is: How do the endpoints work? How does the system know when to stop the fold/unfold motor. There seems to be no sign of endpoint sensors or anything? Does the ECU sense resistance (reached endpoints or any obstacle for that matter) through a current peak or something? Thanks for some input (this is our of curiosity, I have no problem related to this)

06-10-2015, 12:23 PM	#2
LucidMomentum No Money, No Problems Join Date: Sep 2014 Drives: 2015 Scion FR-S (Halo White) Location: Bakersfield, CA Posts: 901 Thanks: 740 Thanked 678 Times in 354 Posts Mentioned: 11 Post(s) Tagged: 0 Thread(s)	No clue, but I'm going to guess that it's probably a motor rated for just enough force to push them in / out, but not further if it hits any serious resistance. Maybe special gearing or something. I doubt it's a sensor though. Seems like overkill when you can do it mechanically. __________________

06-12-2015, 11:59 AM	#3
KellieRahne It's pronounced "Rain" Join Date: Dec 2014 Drives: 2013 Firestorm 6MT Location: Virginia Beach Posts: 51 Thanks: 47 Thanked 72 Times in 37 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	It might hit a limit switch that isn't annotated on the schematic. Keeping even a low torque DC motor energized can seriously damage the motor windings or cause brush burn, depending on the design of the motor. The "black box" that the motor leads go through may be some kind of controller. A more detailed schematic would be nice. __________________ I want to be the girl with the most cake.

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06-13-2015, 01:40 PM	#6
Fish Senior Member Join Date: May 2012 Drives: 2015 Yuzu RS1.0 Scion FR-S #893 Location: San Fernando Valley, CA Posts: 913 Thanks: 459 Thanked 414 Times in 264 Posts Mentioned: 35 Post(s) Tagged: 1 Thread(s)	It might use the voltage readings to determine endpoints. Similar to windows with auto up and down. When it hits the end, the sudden stop causes a spike in voltage that the control unit can see. The control unit then memorizes that voltage spike and can use it to determine position of windows. My guess is the mirrors may operate the same way. Some cars use relays as well. I think our cars might also use an energized relay for the windows. I can't say for certain. It's been a really long time since I've looked at wiring diagrams for things like this. But who knows. Every manufacturer does things differently.

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