injurylawyer

I had installed the Depo tail lights and now the smoked third brake lights and lost my cruise functionality.

It seems to be common since what I am reading is that in addition to the 50w 6ohm resistors for the tail-lights, you would also need the resistor for the 3rd brake light.

The issue is do I need one for the recessed one as well as the one in the electric spoiler? If so, how did you mount your resistor for the lights in the spoiler when you should not attach it to plastic because of the heat generated?


Any input would be appreciated.

5CHN3LL

Running the resistors in parallel gives the circuit multiple paths to completion, decreasing total resistance.

Example: If you install two 12-ohm resistors in parallel, the total resistance is 6 ohms. If you install two 12-ohm resistors in series, the resistance is 24 ohms.

Installing resistors without understanding this concept isn't a great idea...

injurylawyer

I agree.

I know to run them parallel to the circuit and that is not a problem.

The issue is first, whether I would need a resistor for each of the two third brake lights (one in the recessed cowl and the other in the electric spoiler)? I believe I will need one for each in that the recessed one does not work by design when the electric spoiler is up and the one in the spoiler 'takes over.' So it seems that they are separate depending on whether the spoiler is up or down.

The second is if the first is in the affirmative, then where would you mount/secure the resistor since the third brake light in the automatic spoiler is essentially plastic (not wanting to mount something that would heat up on plastic)?

Any ideas/photos are appreciated.

Thanks.

5CHN3LL

I couldn't find a diagram to answer your first question. Since the resistor will only heat when you're on the brake, do you anticipate it getting enough use to melt the light assembly? Options would be to secure it using an adhesive that doesn't conduct heat well and/or using a heat sink on the resistor in that location...

injurylawyer

My thinking was like yours, mounting it to the back of the unit itself would be the easiest. However, wherever you look, the general warning was to avoid such.

The 3rd brake light on the 996 MK1 (mine is a '99) actually only has a hot and a ground.

I agree, a good 3M adhesive double sided tape would be my thought too on the back of the LED housing since you would not anticipate long periods of braking with the spoiler up.

So do you agree the spoiler brake light would require a separate resistor too?





I believe the first applies to the 3rd brake light on the 996 MK-1.

krafty

Ordered my LED's from Del Rey Customs for about $700 for tails and 3rd brake. Plug and play, built in resistors. No warning lights. Work as advertised. Love the updated look.

Ahsai

Do your depo LED lights already have built-in resistors? If they do, you may need an extra 6~8 ohm 50W resistor (to create a similar load of the 3rd brake light) wired in PARALLEL to ANY brake lights as the the brake lights are all wired in parallel sharing the same power source that comes from the brake light switch.

5CHN3LL

You could always test the resistance across one of the circuits before and after adding a resistor to the other circuit. If you see a corresponding change, you'd know that one resistor is affecting both light circuits...

A diagram would be better than poking around with a multimeter, but if all you have is the multimeter...

*edit* or Ahsai might pipe up at any moment with the missing bit of info.

injurylawyer

I like your car...I like the aero kit.

My lights are the Depo tail lights that Del Ray Customs also sell. The resistors were already installed on them so no problems.

My issue was adding the LED 3rd brake light too. The ones I got did not have resistors so I am wondering, when you got yours, do you remember where the resistors were installed (i.e.-double sided mounting tape to the back of the housing)?

Thanks.

injurylawyer

Yes they do. That was my thinking the same thing too.

So, with both the normal recessed 3rd brake light and the one in the spoiler, I would need one each, correct?

Also, suggestions on mounting the resistor, especially for the spoiler 3rd light would be appreciated.

Ahsai

I've already given my answer in post #22 and hopefully you found the what you need. My info is from checking the actual wiring in the '99 wiring diagram.

Ahsai

Our posts crossed.

So you have installed the new LED 3rd brake lights on BOTH the normal recessed area and the spoiler?

Ahsai

There's a spoiler motor driven switch that directs the power to either the normal 3rd brake light or the spoiler brake light depending on whether the spoiler is raised. So one and only one of the 3rd brake lights will be ON when you press the brake pedal.

If both 3rd brake lights were replaced by LED, all you need is to wire a 6~8 ohm 50w resistor in parallel to ANY of the brake lights including the rear brake lights. You can mount the resistor inside one of the rear brake light cavities.

If you replaced only one of the 3rd brake lights with LED, you need to wire the resistor ONLY to that LED 3rd brake light.

injurylawyer

No problem. Appreciate any help.

Yes, I have installed 2 new LED 3rd brake lights.

Neither had a resistor.

I take it from reading #22 that each will need one...in your opinion, where would you mount it with regards to the spoiler 3rd light?

injurylawyer

I guess our writing has crossed again.

I read that you would suggest the cavity where the brake light is recessed. My only concern is that the recess for the spoiler is a plastic like material and the warnings about heat concern me...should I be with the one in the spoiler. Another contributor suggested to mount it to the back of the LED housing since the brake lights are really not on for any extended periods typically with the spoiler up.