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Assistance with Car Folding Mirror Project

Discussion in 'General Electronics Discussion' started by TunerMax, Feb 28, 2012.

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  1. TunerMax


    Feb 28, 2012
    I found some very helpful threads that were similar. I do apologize in advance, like many posters, my electrical knowledge pales in comparison to most of yours. Which is why I'm here looking for help

    here's one thread that is the most similar to my circumstances:

    With my situation being different, I was unable to get my answers from the other threads.

    This is a long Post, I didn't want to leave anything out, so bear with me to get this started

    Here's what I have going on:

    I have 2 folding mirrors, the DO have built in limit switches (current switches I think actually but it's not important).

    This was good news to find out because it simplifies my wiring.

    (I will be uploading the diagrams I've roughly drawn up as soon as I'm home, I cannot upload from this computer)

    I have an OEM folding mirror SWITCH too, but no diagram for it so I had to test it out. It seems the following is true for it:

    Terminal 1 = Output to Mirror Motor (+/-)

    Terminal 2 = Output to Mirror Motor (+/-)

    Terminal 3 = Ignition Power +

    Terminal 4 = Constant -

    There are 3 switch positions with no spring return to neutral. One is FOLD OUT, one is FOLD IN, and then NEUTRAL

    Obviously FOLD IN and FOLD OUT alternate consistant power/ground out to the Mirror Motor terminals. And Neutral seems to be isolated completely, this was good news also.

    So now you know what I have for a SWITCH and for an OUTPUT already. Here's what I want to acheive:

    When I press the LOCK button on my Key Fab, the mirrors fold in.

    When I turn the IGNITION to "ON" the mirrors fold out.

    I plan to keep the Folding Mirror Switch in the NEUTRAL position at all times during the uses listed above. If it's left in either FOLD OUT or FOLD IN positions on the Folding Mirror Switch, then obviously I could have a Short due to reversing polarities. I plan to fuse/circuit breaker both outputs to the Motor as added protection of course.

    What I've considered so far:


    Using a N.O. Latching Relay for the LOCK function. This would allow me to press the LOCK button only once (pulse) but have the mirrors fold in all the way. The issue with this is I don't know how to RETURN the Relay to the N.O. position, I'd assume that I need to run another trigger from the IGN "ON" relay to trip it back to N.O. state BEFORE it sends power the other way. I also though about using a NOTO Relay with a timer around 10 seconds for this function. Unsure if this is best?


    This one I'm kind of lost on. At first it seemed simple, a standard SPST relay should work, but this poses an issue with the normal "manual" function of the switch. If the key is in the "ON" position, then the Folding Mirror Switch is powered also. This is an issue I'm not sure how to overcome, because the Folding Mirror Switch is a fairly sealed unit.

    Before I suggest ideas on overcoming this, I will rather humble myself, and put it to your suggestions. You likely have a much better and simpler Idea for this issue than I.

    To sum up, my issues/questions:

    LOCK (FOLD IN) FUNCTION: Need to determine the proper/ideal "latching relay" or "timed/holding" relay, or other suggestion to control pulse signal. Is a NOTO SPST relay with about a 10 second time best?

    KEY "ON" (FOLD OUT) FUNCTION: Running a standard SPST relay for this AUX function poses an issue with the normal "manual" function of the switch. If the key is in the "ON" position, then the Folding Mirror Switch is powered also.

    I found 1 unit that seems it may work for both functions, but I'm unfamiliar with it:

    And also a bunch of wiring options here, but I'm kind of unsure which suits my application best, if any:

    Of course, your help is very much appreciated. I was hoping to finish this project this weekend, but this electrical hurdle has me scratching my head.

    Thanks in Advance guys!
    Last edited: Feb 28, 2012
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    A simple way to reverse motors is to have 2 x SPDT relays. You connect the common connections to the motor. Ten you connect the NC connections to +ve and the NO connections to -ve.

    you have 2 switches (or other devices) which provide power to one relay r the other to make the motor go one way or the other.

    If both buttons are pressed, nothing happens -- it's safe.

    Then all you need is a circuit which provides a suitable duration pulse when the ignition is turned off, and another when it is turned on. These pulses provide power to one relay or the other to pull the mirrors in or to extend them.
  3. TunerMax


    Feb 28, 2012
    I can tell you have this visualized, I'm hoping you can help me a little father with it though.

    A diagram of this would help. for sure. So I somehow wire it so that 2 relays work together and are both hooked to the +/- wires to the motor? So that when one trigger actuates the coil engergizes and sends the correct polarity one way, and when the other trigger actuates, the polarity is switched the opposite way?

    Could this mean 2 latching relays, and when one is active the other is turned inactive? The only other thing is the Primary manual switch mentioned, if one of these Relays is active / 'held' and the manual switch operates, I would have a short.

    Again, I cannot access the mirror limit switches, nor the Manual switch components. Only the OUTPUTS to the motors and the triggers I wire in.

    What did you think of the idea of using a TIMED relay with an external CAP/Resistor for this? Wouldn't that solve my issues
    And if so, what CAP/Resistor should I be using to get around 10 seconds of engergized time?
    Thanks for your thoughtful reply sir! I am feeling like I'm getting close already :D
    Last edited: Feb 29, 2012
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    No problems. I'll see what I can do...
  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    How's this:


    Id actually recommend that the NC connections go to ground and the NO to 12V, but you can just swap that over.

    Attached Files:

  6. TunerMax


    Feb 28, 2012
    Ok given your diagram I tinkered a bit. I changed some connections, and also omitted the Transistors. I did this because, honestly I have no idea why they're there :confused:
    The removal was simply to help me understand the schematic, if you can explain why I need them or how to wire them I'd be grateful, cause I'm not getting it :eek:
    I also labled some terminals/components because I'm kind of lost without that.

    Here's how I understand it can work, without considering that the signals for the triggers are pulsed, or that there is a Manual switch incorporated also:


    I also tried my hand at incorporating the Manual switch. I figured I can tap into what WERE the mirror motor output wires and use them as the Triggers. One wire to each relay's trigger. When + is active on one, - will be active on the other, and vice versa for FOLD IN and FOLD OUT positions. This means that when one is -, the trigger from the (LOCK/START) circuit could short out. I added a Diode to stop this, will that work?This seems like it will work can you please look it over and tell me if I've missed something, or if I should be including something I'm not?


    Thanks so much for your patience with a noobian! We all started somewhere right :D

    Last edited: Feb 29, 2012
  7. TunerMax


    Feb 28, 2012
    Also, I need to figure out how to wire up the timed delay operated by a pulse signal.

    this shows (I THINK) how to do it with a CONSTANT pulsing signal (turn signal), not sure how to do it with a single momentary pulse though.
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