On/Off switch for interior hatch light

SpringRubber

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Looking for a clean option to install an on/off light switch in the hatch area on a 2018 Sport. Stock allows the light to stay on as long as the hatch is open. <deleted>....is there an easy fix to put an on/off in the hatch?

Updated to add pics of the light I'd like to control from the hatch area:

Honda Civic 10th gen On/Off switch for interior hatch light hatch light 1.JPG


Honda Civic 10th gen On/Off switch for interior hatch light hatch light 2.JPG


Honda Civic 10th gen On/Off switch for interior hatch light hatch light leads
 
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kperalta

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Looking for a clean option to install an on/off light switch in the hatch area on a 2018 Sport. Stock allows the light to stay on as long as the hatch is open. Yes, I can turn off the interior lights on the stalk but is there an easy fix to put an on/off in the hatch?
I believe it is either controlled by the BCM or its done with the hatch pin as a negative trigger. You can run a switch in series if its the second option I'm pretty sure. You'll need a Single Pole Double Throw Switch, with the common terminal attached to the car side of the wire. The normally closed completing the original circuit and the normally open attached to ground. That way, with the switch off it still grounds out when the hatch opens, and with it on it grounds out and turns it on. It'll also probably say the hatch is open though.
 
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I believe it is either controlled by the BCM or its done with the hatch pin as a negative trigger. You can run a switch in series if its the second option I'm pretty sure. You'll need a Single Pole Double Throw Switch, with the common terminal attached to the car side of the wire. The normally closed completing the original circuit and the normally open attached to ground. That way, with the switch off it still grounds out when the hatch opens, and with it on it grounds out and turns it on. It'll also probably say the hatch is open though.
Thanks and the second option is indeed there -- with the hatch open I manually pushed the latch closed and the light goes out.

I'll have to noodle to understand why a SPDT vs a SPST switch would be called for -- sure don't want to create a problem just to give me some convenience!

I updated the post with some pics. Just 2 wires into the fixture, red and blue. But there isn't any play at all in the length so to put in a rocker switch or similar would require removing the panel, making the connections and cutting an opening to mount the switch.

I did mess up on my post -- one can't actually control the 18 Sport hatch light from the driver's seat (at least not that I know of). But that makes for a simpler circuit.

Easiest would be is someone knows of a plug and play solution, i.e. a lampholder that has a switch in it (eg. like the dome light does -- except without the wiring there for dimming). Thanks folks!
 

kperalta

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Thanks and the second option is indeed there -- with the hatch open I manually pushed the latch closed and the light goes out.

I'll have to noodle to understand why a SPDT vs a SPST switch would be called for -- sure don't want to create a problem just to give me some convenience!

I updated the post with some pics. Just 2 wires into the fixture, red and blue. But there isn't any play at all in the length so to put in a rocker switch or similar would require removing the panel, making the connections and cutting an opening to mount the switch.

I did mess up on my post -- one can't actually control the 18 Sport hatch light from the driver's seat (at least not that I know of). But that makes for a simpler circuit.

Easiest would be is someone knows of a plug and play solution, i.e. a lampholder that has a switch in it (eg. like the dome light does -- except without the wiring there for dimming). Thanks folks!
Taking off the the panels and running some extended wires is what I'd do, but this kind of stuff is easy for me. For sure let us know what happens! Also, even if the wires are present in the back it could still be connected to the bcm. You'll just have to check what happens at the light with a multimeter. Also, a SPDT switch is necessary because a SPST switch will just interrupt the circuit and won't do anything.
 


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Just get the factory dome light with a switch from other models:

34265-SFE-003
Ah, that p/n comes up as a cargo area light for CR-V and others. I ordered it and will report back. CR-V and Crosstours apparently have 2 of these (whereas civic hatch sport just one) according to this CR-V diagram (item #5). Found a video of someone replacing the bulb (which I guess he already replaced, as it shows an LED). But this is the feature I'm looking for.


Honda Civic 10th gen On/Off switch for interior hatch light 2017 CRV int light
 
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SpringRubber

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Also, even if the wires are present in the back it could still be connected to the bcm.
I am still tracking that point -- BCM being a logic controller, if I understand correctly.
 

kperalta

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I am still tracking that point -- BCM being a logic controller, if I understand correctly.
Body Control Module yes. The only issue it'd cause if it is caused by that is the switch would cause your dash cluster to show you have your hatch open.
 
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Update: I swapped in the exactly same-sized & switched lampholder/lens for the CR-V cargo area and it works! When the hatch is open I can flip the switch and the light goes off.

p/n 34265-SFE-003

Pricey part (collegehillshonda online price was $22) but it was plug-n-play.

However, the lens I swapped in does lack a circuitry component that is in the hatch lens. Top is from the hatch and see that diode looking thing? Maybe this is why @kperalta called for a specific type of switch. In my sport hatch (not the Touring with all the other gizmos) this works fine but my only concern is this: Did I remove a safety thing?

Honda Civic 10th gen On/Off switch for interior hatch light IMG_2732.JPG


Honda Civic 10th gen On/Off switch for interior hatch light IMG_2731.JPG
 

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Update: I swapped in the exactly same-sized & switched lampholder/lens for the CR-V cargo area and it works! When the hatch is open I can flip the switch and the light goes off.

p/n 34265-SFE-003

Pricey part (collegehillshonda online price was $22) but it was plug-n-play.

However, the lens I swapped in does lack a circuitry component that is in the hatch lens. Top is from the hatch and see that diode looking thing? Maybe this is why @kperalta called for a specific type of switch. In my sport hatch (not the Touring with all the other gizmos) this works fine but my only concern is this: Did I remove a safety thing?

IMG_2732.JPG


IMG_2731.JPG
A diode allows current to run in one direction but not another. Itā€™s exactly like a check valve in piping. It does protect the electrical system in general applications and the CRV and Civic could have different wiring that allow for different component uses. I wouldnā€™t worry too much, just be aware it could create issues down the road such as flickering, the light failing, and feedback into other electronics.
 


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I believe it is either controlled by the BCM or its done with the hatch pin as a negative trigger. You can run a switch in series if its the second option I'm pretty sure. You'll need a Single Pole Double Throw Switch, with the common terminal attached to the car side of the wire. The normally closed completing the original circuit and the normally open attached to ground. That way, with the switch off it still grounds out when the hatch opens, and with it on it grounds out and turns it on. It'll also probably say the hatch is open though.
Why would you need to have the circuit grounded if the switch is off? If you would use a SPST switch, there will be no load so I wouldnā€™t see this having any issues? I mean, I could understand faulty wiring, but if the switch was in the second position with a SPDT switch and had the same faulty wiring the same issue would occur. So I wouldnā€™t see the upside, the SPST would include one less wire you need to worry about. Also, I donā€™t think there would be an issue with the BCM...when you open the hatch itā€™s an input that controls the output, the hatch light. I doubt thereā€™s feedback from the hatch light to the BCM telling whether the circuit is complete or not. One way to test is remove light and have hatch closed and see if BCM recognizes it as being open.
 

kperalta

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Why would you need to have the circuit grounded if the switch is off? If you would use a SPST switch, there will be no load so I wouldnā€™t see this having any issues? I mean, I could understand faulty wiring, but if the switch was in the second position with a SPDT switch and had the same faulty wiring the same issue would occur. So I wouldnā€™t see the upside, the SPST would include one less wire you need to worry about. Also, I donā€™t think there would be an issue with the BCM...when you open the hatch itā€™s an input that controls the output, the hatch light. I doubt thereā€™s feedback from the hatch light to the BCM telling whether the circuit is complete or not. One way to test is remove light and have hatch closed and see if BCM recognizes it as being open.
Well you see here my smart friend you, door pin triggers are commonly negative triggers. Meaning, that when the trigger is pushed in, it'll read 12v. Then, when it's out, it goes to ground, thus completing the circuit it's attached to. Because it becomes a ground. Now, if you'd like for me to explain how electricity works, I'd love to, but I'm not going to assume you don't know anything . So, the reason why you need a SPDT switch is to retain the original circuit. If the light is a basic circuit, and not a data control circuit, then the light either turns on via either a) switching to ground or b) switching to positive via the hatch pin. So, in order to turn on the light, you'd either have to take it to ground, or take it 12v, thus turning it on.

Now another basic understanding of 12V is that a BCM that is completely data controlled doesn't really exist, as despite the advances in car technology, the circuitry and even the audio is still significantly analogue. A door pin is either a negative or positive trigger to complete a circuit. Power locks or power unlocks are either a negative or positive trigger. Domelights are usually connected to a door pin and are usually controlled via a negative or positive trigger. The dimmer dash lights are a variable voltage trigger on which the circuit is completed even to turn them on is a negative trigger. Heated seats are normally variable voltage positive triggers, but unfortunately, in our cars they are data controlled. Hell, even the head lights turn on via a negative trigger, and I would know, because I took a a relay and attached it to that circuit to turn on my interior leds only when the head lights are on.

In relation to the BCM, when the BCM senses when the doors are open, it is done so via the door pin, which my friend, is a negative trigger that tells the BCM via an analogue method that the door is open. Oddly enough though, the way that the BCM tells the dash cluster the door is open, is through data. So, in result, if the hatch pin is negative trigger that completes the circuit of that light and also tells the BCM the hatch is open, interrupting that circuit and putting a SPST and switching it on when you want it on, does NOTHING unless the hatch is open. It just breaks the circuit unless you want it on. A SPDT switch creates two circuits. One in which is always ground, and the other which is switched ground (aka the original circuit) the always ground one, completes the circuit, and turns the light on. But it also let the BCM know that oh, the negative trigger is now on, aka the hatch is open. Perhaps it does that, perhaps it doesn't. I don't care enough to go looking through the wire diagram of the light. Maybe the light is its own circuit, but shares the common ground of the door pin. Maybe it's a positive trigger. I have no idea. Don't really care, but that doesn't mean I can't suggest a few things based on the knowledge of 12v I have.
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