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Brake LED Light Array (Top Center of Hatch Door)


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1995 Nissan Pathfinder - XE - V6


Austin, Texas: DPS says you can't get a brake tag if your "Third" Brake Light is not working.....

Brake Tag station attendant said that the light is out.


The 3rd Brake Light is actually working but very dim.

Upon removal of the light, voltage was tested across the Green and Black wires: 12 VDC

Hooked up the LED light array to another 12 VDC source to verify: Same results, a very dimly lit LED array.

All LED's appear to be lighting up, just very dim.


I inspected the printed circuit board and drew a schematic (see pdf attachment)


Also, having trouble finding this particular circuit in the 1995 NP Service Manual:



I know I may have to replace the lights with an alternative (perhaps 2 or 3 incandescent or something),

but since the LED's all light up (dimly), I figure there may be a chance to the repair circuit, or at least, confirm what is going on (what's failing).



Thank you for any advice.


1995 NPathfinder XE-V6 - Brake LED Array.pdf

1995 NP-XE-V6 - Brake LED Array - 20190117_223000 - CMP.jpg

Edited by jasenpeters
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From Diode Dynamics:

Since automotive power is 12V, and LEDs generally run best on 2-4V, depending on color, you must use resistors or other components to drop the voltage to a level the LED can work with. This is why you cannot simply plug a basic LED directly into your socket, or connect it to a 12V battery. The manufacturer will determine what the nominal (normal) voltage is to run a specific LED, known as the "forward voltage." For example, a blue LED might be rated as 3.0-3.2V. Adjusting the _voltage_ lower or higher will change the brightness, but only because it also changes the _current_; higher voltage means the current will increase in an LED.

After ensuring that you have the correct voltage available to the LED, the next step is determining current. This is measured in amperes, or amps, but since it's such a small amount of current, LEDs will be rated in milliamps (mA). The more current, the brighter the LED, but there is always a maximum "running" or "constant" current, which is the max you should run the LED at, and usually there is a max "peak" current, which is the highest current the LED can withstand before completely failing.



That being said I would suggest that you have either 1) an increase in resistance within the circuit board (likely, considering the possible water intrusion , location and age of the brake light) or 2) a weak grounding point. We know that the voltage is good, so that leaves only either 1) increased resistance (from corrosion, vibration, bad wire, bad ground?) or 2) a reduction in supplied power (cracked wires, poor contact surfaces). Not that this is much help to you but without seeing the board in detail there is a lot that I can't rule out!




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I'm thinking the trouble is at the board.

I'm confident I traced the circuit board and have drawn the schematic correctly.

I could sent closeup pix of the various sections of the PCBoard if that would help.


I tested the connector (on the hatch) supplying the voltage and it was about 12 VDC (give or take),

and, I tested a Dome light bulb to see if there was perhaps a current supply problem, but the test was only visual.

The dome light lit up with normal brightness. So, I assume it can supply what's needed (perhaps).


I also tested the LED strip(s) on a separate DC power supply, and the results were the same: Lowly Lit LED's.


I even bypassed the limiting Diode at the beginning of the circuit with the same results, lowly lit LED's.


I'm thinking I would have to somehow isolate each parallel line to see if perhaps, one of the series lines are

drawing too much current away from the rest...?


I don't mind the time it takes to do this, because I'm curious about the phenomena of what's going on.

Other forums, so far, are suggesting buying a new strip. I get it. But I enjoy finding things out.

That was an excellent explanation, and it gives me much to consider.

Thanks for taking the time to write it out.


I'll keep you posted on any further results.


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The third brake light on my '93 sucked when I got it. Some of the LEDs were trying harder than the others, but they were all pretty dim. I too took it apart expecting a smoking gun (moisture, corrosion, something burned up inside) and didn't find anything obvious. LEDs have a life span like anything else, and I figured mine had just worn out over twenty-odd years and 230-odd thousand miles of urban driving. I had a good one in my parts car, so I didn't spend too much time troubleshooting the bad one before swapping it out for one I knew worked.

I doubt the issue is one string drawing excessive current. I think you'd see evidence of heat or blown fuses if that was the case. I'd verify that the voltage across each string is the same as the supply voltage (to rule out high resistance in a joint or trace or something), maybe test an individual LED on 3v to see if it lights up properly, and if both of those come up negative, order a bag of red 5mm LEDs and get ready to do a whole lot of soldering.

If that doesn't sound like fun, there are aftermarket ones on Fleabay. They've got red ones, they've got black-tinted ones if you like painting your lights so they work less, and they've got clear ones because Altezza, yo. I didn't check to see if Nissan still sells them, but yeah, I wouldn't be surprised.

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From Diode Dynamics.....

That’s a phenomenal explanation from Diode Dynamics! That really is incredible customer service. I’m amazed someone took the time & care to write all that out. I feel good about having purchased their LEDs.
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That’s a phenomenal explanation from Diode Dynamics! That really is incredible customer service. I’m amazed someone took the time & care to write all that out. I feel good about having purchased their LEDs.
Yea DD has a lot of good stuff! I'm going to plug my phone in and slide over to my laptop to do some more reading this afternoon.

Sent from my SM-G386W using Tapatalk

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---> Slartibartfast

You are correct.

After disconnecting the hot side of the resistor to a few of the random groups of 4 LED's...

None showed signs of improved brightness. I figure they are shot, old age....


I replace a few groups with some high output thru-hole LED's (I had some extra lying around) and the lit up bright as normal, ready for inspection.

So, I've ordered another 50 or so to finish the job later.


Yes, it's tedious, but it is also fun.


I'll update with some final thoughts after I get the parts and get it working back to normal stock operation.


Thank you all for your help, much gratitude.


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I replaced all 68 LEDs

5mm Clear Red High Bright

2.1v/30mA was the final measurements

At about 13.2v Source.


Took about 2hrs.


Passed the inspection.


Thanks yall :)




Edited by jasenpeters
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  • 1 month later...

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