[NotFast]

[Please move is this the wrong forum]

The reverse lights in the LT1 are beyond horrible - when I back up at night, it's like there are NO bulbs. I'm trying to replace them with some VLED 7440 bulbs but I've run into this weird issue:

When replace the left side bulb - it works great.
When replace the right side bulb - it works great, but then both reverse bulbs STAY lit (but dimmer) after the car is locked and the all the other lights turn off.

I'm guessing there is something weird in the wiring harness that continues to push a slight voltage with that LED bulb, although it doesn't make sense.

Anyone have any suggestions or ideas? I can run with one LED bulb but that's a little weird, too...

Dim LED:




Bright/normal:

[GroundhogSS]

When you change out the incandescent bulbs with led, you have to put a resister across the circuit. Lots of places to get the resisters. I got some from Diode Dynamics and some from Amazon. Read these threads.



https://www.camaro6.com/forums/showt...ckup+light+led


https://www.camaro6.com/forums/showt...ckup+light+led

[NotFast]

Originally Posted by GroundhogSS

When you change out the incandescent bulbs with led, you have to put a resister across the circuit. Lots of places to get the resisters. I got some from Diode Dynamics and some from Amazon. Read these threads.



https://www.camaro6.com/forums/showt...ckup+light+led


https://www.camaro6.com/forums/showt...ckup+light+led

THANK YOU! I do now remember reading those threads but I've read so much over the past month here that I'd forgotten.

[UnknownJinX]

Oh heh, we are using the same bulbs!

I used a 200-ohm resistor on each bulb and soldered it on, like this. Make sure the solder is closer to the top so the bulbs can fit into the socket.

Way cheaper than buying a big resistor and tapping your wires.

They are very nice and bright. I like them way better than the stock bulbs which are very dim as you mentioned.

The reason, from what I understand, is that this car uses an electronic switch for reverse bulbs(like a transistor) rather than a physical switch. The electronic switch leaks a small amount of current even after the car shuts off. The halogen bulb masks this fact as it needs more power to illuminate, but the LED bulbs will light up with this small current.


Sent from toaster or something

[NotFast]

Originally Posted by UnknownJinX

Oh heh, we are using the same bulbs!

I used a 200-ohm resistor on each bulb and soldered it on, like this. Make sure the solder is closer to the top so the bulbs can fit into the socket.

Thanks. I just ordered some 200 ohm's from Amazon.

[2SS Capt]

Originally Posted by UnknownJinX

Oh heh, we are using the same bulbs!

I used a 200-ohm resistor on each bulb and soldered it on, like this. Make sure the solder is closer to the top so the bulbs can fit into the socket.

Way cheaper than buying a big resistor and tapping your wires.

They are very nice and bright. I like them way better than the stock bulbs which are very dim as you mentioned.

The reason, from what I understand, is that this car uses an electronic switch for reverse bulbs(like a transistor) rather than a physical switch. The electronic switch leaks a small amount of current even after the car shuts off. The halogen bulb masks this fact as it needs more power to illuminate, but the LED bulbs will light up with this small current.


Sent from toaster or something

What about heat from the resistor??? Couldn't it melt the plug? I know the typical 6 ohm 50W resistors have a large heat sink on them...

[UnknownJinX]

Originally Posted by 2SS Capt

What about heat from the resistor??? Couldn't it melt the plug? I know the typical 6 ohm 50W resistors have a large heat sink on them...

Those large resistors with low resistance are designed for hyper-blinking LED turn signal bulbs experience when you retofit them on a car with halogen turn signal bulbs. They need that surface area to dissipate the heat as they need to consume enough power to trick the BCM into thinking that there is a halogen bulb in place.

The resistors on reverse bulbs are different. All it has to do is to "absorb" the small amount of leakage current the switch let's out so it doesn't go through the LED bulb instead. A resistor of much higher value will be fine.

With a 200-ohm resistor, it will only consume (14V)^2/(200ohm)=0.98W. This means a 1W resistor will be 100% OK. I think even a 1/2W unit will be fine, as reverse bulbs usually don't stay on for long enough for heat to become an issue.

The idea is to use a resistor that has the highest resistance possible without the LED illuminating. In the case of these VLED 7440 bulbs, 200-ohm is the highest I got to. Maybe 300-ohm is fine, but I know the 400-ohm one I tried doesn't work correctly.

A lot of my knowledge comes from cellsafemode's posts. Just making sure they get the credit.

Sent from toaster or something

[NotFast]

Thank you


I'm no electrical engineer, but my gut says that the backup lights would not be used enough to build up much heat. When I was messing around with my VLEDS earlier - they were only somewhat warm, but these are designed with heat sinks on the top:

[2SS Capt]

Originally Posted by UnknownJinX

Those large resistors with low resistance are designed for hyper-blinking LED turn signal bulbs experience when you retofit them on a car with halogen turn signal bulbs. They need that surface area to dissipate the heat as they need to consume enough power to trick the BCM into thinking that there is a halogen bulb in place.

The resistors on reverse bulbs are different. All it has to do is to "absorb" the small amount of leakage current the switch let's out so it doesn't go through the LED bulb instead. A resistor of much higher value will be fine.

With a 200-ohm resistor, it will only consume (14V)^2/(200ohm)=0.98W. This means a 1W resistor will be 100% OK. I think even a 1/2W unit will be fine, as reverse bulbs usually don't stay on for long enough for heat to become an issue.

The idea is to use a resistor that has the highest resistance possible without the LED illuminating. In the case of these VLED 7440 bulbs, 200-ohm is the highest I got to. Maybe 300-ohm is fine, but I know the 400-ohm one I tried doesn't work correctly.

A lot of my knowledge comes from cellsafemode's posts. Just making sure they get the credit.

Sent from toaster or something

Excellent, thanks! Wonder why the bulb manufacturers aren't adding the resistors to avoid the problem in the first place?

[NotFast]

Originally Posted by 2SS Capt

Excellent, thanks! Wonder why the bulb manufacturers aren't adding the resistors to avoid the problem in the first place?

I don't think other cars have this issue. VLEDS doesn't even say this 7440 bulb is compatible with the Camaro, but I'd swapped out a number of bulbs on other cars and decided to take the gamble.

[kropscamaro16]

need a resistor use the gen5 diy kit easy as pie

[cmeJATT]

just put resistor on the bulb lol

[cellsafemode]

the load resistor (small ohm) is needed for bcm's to not trigger hyperflash or warn you a bulb is faulty. That tends to not be the case for the reverse lights (though newer MY's have changed a few things up).


The reverse light has current leaking from the parking switch. This power normally is shunted thru an incandescent filament but it's not high enough to make it glow ...but it is enough to power led's a bit depending on the bulb.

You dont need a load resistor on the reverse lights to solve this issue though. A 2 to 20kohm or so quarter watt resistor should be wired between power and ground on the reverse circuit and this should shunt enough current to not trigger the led's to glow when "off" without wasting a bunch of power and getting hot.

the load resistors are needed for things like blinkers (where the oem used halogen bulbs). i prefer the remote mount load resistors you can mount to some good metal to heat-sink the heat away. I do not like bulbs that build them in as it generates even more heat in a tiny area where leds are already going to be running hot - potentially limiting the lifespan of the bulb.

[UnknownJinX]

Originally Posted by NotFast

Thank you


I'm no electrical engineer, but my gut says that the backup lights would not be used enough to build up much heat. When I was messing around with my VLEDS earlier - they were only somewhat warm, but these are designed with heat sinks on the top:

For the short time they are on, you probably won't build up much heat. VLEDS doesn't recommend leaving it on for too long. These are some pretty bright and powerful LEDs, which also generate a bit of heat that can build up over time.

Originally Posted by 2SS Capt

Excellent, thanks! Wonder why the bulb manufacturers aren't adding the resistors to avoid the problem in the first place?

cellsafemode's answer makes sense if we are talking about a low-ohm resistor that consumes more power and generates more heat. LEDs don't like a lot of heat. When they get too hot, they get into a negative loop of efficiency drop -> more heat due to efficiency loss -> even lower efficiency -> even more heat...

For Camaro's application, you could potentially fit a small high-ohm resistor in there(200-ohm for this particular bulb), but given how expensive these bulbs are, I am not gonna attempt to mess with the wiring inside. There is probably not enough demand on the manufacturer side to make changes like this, either.

Originally Posted by kropscamaro16

need a resistor use the gen5 diy kit easy as pie

For the 2019+, it's a lot of work. You are supposed to take off the bumper to put these resistors on. There is someone who did it without taking the bumper off, but I would think it's not easy given how tight it is inside the bumper.

And they are really, really expensive. I am probably looking at CAN$150+ with shipping and customs in Canada.

Originally Posted by cmeJATT

just put resistor on the bulb lol

These VLEDS bulbs are pretty big. They barely fit into the hole and they are long enough that I have to put the bulb into the hole first and then connect it to the socket, otherwise, it just won't go in. I have to fit it just between the socket and the top part of the connector.