I swapped 06-08 LED tails into my 04 Z. The car had aftermarket LED tails (DEPO 'Z' tail lights) before I switched, as that is what was on the car when I bought it. It is supposed to be a plug and play swap, but the lights are not working properly. Here are the symptoms:

When headlights are off:
- Depressing brake pedal only illuminates the lower part of the tail lights, not the LEDs.
-The center upper mount brake light at the top of the hatch does not illuminate at all when depressing brake
- Pink/Blue wire running to the tail lights is receiving ~8V when the brake pedal is depressed.

When headlights are on:
- LEDs in tail lights are lit to full bright all the time even without depressing brake pedal. Depressing brake pedal flickers tail lights very slightly, and only barely visible at night time. The tail lights in this position should be only partially lit, going to full lit only while depressing brake pedal
- The center upper mount brake light at the top of the hatch does illuminate when the brake pedal is depressed. I thought this strange
- Red/Blue wire running to the tail lights is receiving ~12V when the headlights are on.

I did some research and found that a lot of people putting in aftermarket tail lights had to reduce the voltage to the lights to make them work, either by adding an inline resistor or by some other method. I pulled the trunk panels out and noticed the wiring had been tampered with, but could not find any resistors.

The car also has the following electrical/lighting mods (on car when purchased) that may be causing problems;
- illuminated door sills (they come on when opening door, so not sure where they are tied in)
- illuminated rear strut bar (tied in with tail light wiring to illuminate when headlights are on. This works fine)
- LED side markers (illuminate with turn signal, so probably not a problem)
- various audio mods that shouldn't be an issue

My questions:
1) Should the pink/blue wire read 12V and not 8V? If so, is my problem a resistor somewhere or something else (possibly related to the other lighting mods)?
2) Should the red/blue wire read 12V?
3) Should standard OEM '03-05 tails work assuming the voltage is too low for the LEDs?

Any input is greatly appreciated. Thanks

 

Checked out the wiring diagram and it looks like I should be receiving 12V to both the pink/blue and red/blue wires, so there is definitely a resistor or something dropping the voltage to the tails. Can someone please confirm I should be receiving 12V to both wires???

My friend thinks that when the headlights are on, my tails are not actually full bright and are what they are supposed to be at that setting ("running" brightness), but I don't know anyone with a Z to compare brightness to so I can only guess at this point. They looked very bright to me, but who knows. If ideally the tails are getting 12V from both wires, then a pulse width modulator (PWM) must be used to dim the LEDs to the "running" brightness correct? Since the 03-05 models didn't come with LED tails, is there even a PWM to do this?

The wire diagram shows the following circuit for the tail lights:

Battery -> 10A Fuse -> Brake Switch -> Tail lights and Center High Mount Stop Lamp (CHMSL) on the hatch

The CHMSL reads the same low voltage as the pink/blue wire for the tail lights, and so since they are wired in parallel the resistor/problem must be upstream. That only leaves the Brake Switch or Fuse area. I am thinking that the resistor is probably between battery and fuse or between fuse and brake switch, so I will check there. Any other advice would be helpful

 

I swapped my 2003 lights for 2006 and when you do it the 2003-2005 lights have 2 plugs and the 2006 and up lights only use 1. There is only one plug that will work. The other just hangs.

 

Thanks for the response, but that is not an issue. It is the pink/blue wire supplying low voltage to the tail lights that is the problem.

 

I'm having the same issue. Mine is always full light when my headlights are on. When I brake, the taillights themselves don't change brightness. Thinking of swapping back, which is gonna be a pain since I soldered my wires together.

 

I know this is an old thread but I just purchased a 2005 350z with the OEM LED tail lights and I'm having the exact same issues. Was wondering if anyone has a fix for it?

 

Is each and every symptom that is listed above the same that you are having, or only a few?

 

I had the same issues as perfectz I was able to get a volt meter and diagram and figure it out. The brake light power wire goes from the tail light switch on the brake pedal directly to the back. The volt from the wire from fuse box to the switch was 12v but out was only 6v on the pink and blue wire that goes to the tail lights to light up. So decided to replace the brake pedal switch and now it works fine. Guess the switch was going bad.

 

Pretty sure the LED tails were introduced in 06 so there's that. The tails are super easy to remove, my suggestion would be to pull them both and look for modification in the wiring by previous owner. Look for splices and wire colors that don't match.
I'd also google search tail light wiring pics (NOTE I said pics, not diagrams) unless you have a friend with an 05 who will let you look.

 

I installed the 2006+ LED OEM tail lights in my 2003 Z. They work perfectly. Why don't you pull out one of your lights and let us take a look at the wiring. The new lights should have been plug and play unless the previous owner did some strange things with the wiring. Another alternative would be to switch the original set of lights back into your Z and see if they work normally.