Question about circuitry component in trunk light

[hayze]

I am going to add some lights to my trunk by tapping them into the wires that power the trunk light, but there is a small concern I have. In the socket for the OEM trunk light, I found a circuitry component inline. Pictures of it are below.

Does anyone happen to know what it is? If I tap the trunk light wires behind this component, then my new lights won't see whatever that thing does. I'll be 'jumping' that component with my new lights. So if anyone knows what this thing is and what this will mean for my new lights, let me know. Thanks.

The component is pointed to in green below

Here is a few more pics

 

[DonShock]

Usually, small components like that with the stripe on one end are diodes. They let current flow in one direction but not flow in the opposite direction. I'm not sure what it's purpose is since in the pix it looks like both ends are connected to the same point electrically since all the metal on the right side all seem to be connected.

 

[Morelite]

Looks like a standard diode but I don't know why that would be needed there.

What activates that light? Is there a switch somewhere or does the light come on when you tilt it?

 

[Illum]

that's definitely a diode of some sort, judging from the size it'll survive a couple amps...

diodes prevent power from feeding back into a system by effectively turning a wire into a one way highway.
Since the diode is set between the two contacts, it could very well serve as

1. A load for the power supply, some power supplies cannot function if the load side is open circuit, so somewhere something can keep track of that plug even though its not connected to anything. Since its connected to both contacts with a lamp, it could potentially be something used to keep the circuit closed in the event the lamp goes ka-put
2. Bypass diode, connected in parallel, but with opposite polarity, to a power supply. Under normal operation the bypass diode will be reverse biased and will effectively be an open circuit. If there was a short, then the diode conducts, saving you from a possible fire to just burnt electronics
3. Snubber diodes, their used to suppress voltage transients in electrical systems and is often seen wired in parallel with an inductive load like motors and relays

Wiki will explain the snubber better than me

hen current to the inductive load is rapidly interrupted, a large voltage spike would be produced in the reverse direction (as the inductor attempts to keep current flowing in the circuit). This spike is known as an "inductive kick". Placing the snubber diode in inverse parallel with the inductive load allows the current from the inductor to flow through the diode rather than through the switching element, dissipating the energy stored in the inductive load over the series resistance of the inductor and the (usually much smaller) resistance of the diode (over-voltage protection).

I have no idea why you'd have something like that, but given the application location I'm guessing its [1], but as I looked at it closer, no part of the diode appears to contact the other pole. So...why would a [non-LED?] lamp require a diode? half-wave rectification? If its there to drop the voltage [which it may be better than resistors, which reduces wattage, not voltage] why not use a more suitable lamp?


Have you looked at other connectors on the car and see if you find consistent results?

 

[hayze]

in the pix it looks like both ends are connected to the same point electrically since all the metal on the right side all seem to be connected.

It looks like that in the pic, but its actually not all connected. I had to look harder to realize that. All the current has to go through the diode to get from the wire to the bulb.


I haven't seen one of these in any of the other bulbs, but none of the other bulbs are like the trunk light.

Do you guys think that if I jump it with my new lights it will be a problem? What I mean by 'jump' is tap my new lights behind it on the wire.

 

[hayze]

Looks like a standard diode but I don't know why that would be needed there.

What activates that light? Is there a switch somewhere or does the light come on when you tilt it?

I forgot to answer this one. The light comes on when you open the trunk.

 

[Morelite]

I forgot to answer this one. The light comes on when you open the trunk.

I need more info,
does the light assembly turn on and off if you tilt it in your hand or is there a trunk mounted switch that activates by the opening of the trunk lid.
What I'm getting at is that looks like a diode but may actually be a little tilt switch.

 

[hayze]

I'll have to get in there and check. I can always test before and after the component with a DMM. But yea good idea. I'll look for the switch tomorrow.

 

[tebore]

Looks like a diode for sure.

I think it's there because the stock bulb is an LED. At least looking from your pictures it looks like an LED and this is assuming you didn't replace the bulb with an LED.

 

[hayze]

The stock bulb was a regular 194 incan. I replaced it with an LED long ago.

But no, the stock bulb was not an LED.

 

[LukeA]

I need more info,
does the light assembly turn on and off if you tilt it in your hand or is there a trunk mounted switch that activates by the opening of the trunk lid.
What I'm getting at is that looks like a diode but may actually be a little tilt switch.

The light assembly doesn't move when the trunk is opened, so that's not a tilt switch.

 

[bshanahan14rulz]

is it just me or does it look like both leads are soldered to the same piece of metal?

 

[Illum]

is it just me or does it look like both leads are soldered to the same piece of metal?

its not just you, which adds to the confusion.

 

[hayze]

Okay, I checked. That thing is not a tilt switch because the light and diode are not on the moving door. The unit is on the ceiling in the trunk.

Also, the contacts are separate. The diode is inline, and there is no way around it. It looks confusing in the pics, and it looks confusing when I look at it in real life too, but I did notice after examining that nothing is connected like you're saying.

Here is a picture of the basics of the lines.

Trust me, I checked

 

[bshanahan14rulz]

In that case, all it does is make sure the current flows in one direction and not the other. It does drop a certain amount of voltage, probably around one volt, so break out the trusty voltmeter to make sure it can supply the voltage you need.

 

[hayze]

Maybe, when the trunk closes, one of the line's voltage changes to a value such that the current flow reverses and the light stays on instead of turning off like its supposed to. Don't incan bulbs (like my stock trunk light) light up when you swap the pos and neg? Maybe adding the inline diode rectifies the problem. Its just a speculation. I wouldn't know for sure.

If that is the case, then with LEDs, I bet that diode isn't needed anymore anyway. The 5mm wired LEDs (with resistors) I have AND the bulbs I use in the sockets don't turn on if you put them on the battery backwards showing that current can't run through backwards anyway. Does that sound right?

Again, I am just speculating. Let me know what you think of my speculation.

Anyway, I'll post what happens with the DMM as soon as I get to it.

For now, thanks for all you guys' consideration and help.

 

[Vinniec5]

Possibly the way the cars wiring is, when the trunk is closed and the driver uses the dome light switch manually it keeps the trunk light from being back fed and lighting. Also possible tied into the Alarm system if the vechicle is factory equipped. Honda service manual might tell you, the GM manual always did, Chryslers' always left you in the dark.

 

[Illum]

Honda service manual might tell you, the GM manual always did, Chryslers' always left you in the dark.

this would be funny if it wasn't so true:shrug:

 

[bobski]

Maybe adding the inline diode rectifies the problem.

Har har. http://www.diodes.com/datasheets/ds28002.pdf

Possibly the way the cars wiring is, when the trunk is closed and the driver uses the dome light switch manually it keeps the trunk light from being back fed and lighting.

That's my impression as well. I've used diodes similarly in the past when modifying a map light to switch on when a door is opened, like the dome light (it was originally just pushbutton-operated).

 

[Lynx_Arc]

one use of a diode is to reduce the voltage to the bulb which dims it but also keeps it slightly cooler which could help it last longer when the trunk open/closes banging etc.