Right. but whats all this bs about some trucks needing the resistors and some don't? I have the tail lights and the bar all coming, should i wire it up as is and see if i trip the ABS warning?

Then pick a resistor if needed? I don't particularly like the idea of that resistor heating up to that high temp. so if i have to I can model the circuit in Pspice and play with some values.

Not to mention are we sure that person didn't short over the resistor in order to get it to heat up as much as it did? if hes using around 60% load, that seems very hot.

 

LED's dont function like a typical lightbulb... once they hit their threshold voltage, LED's have a pretty much constant light ouput. They don't get brigther with more voltage or current (It's very negligible...). They're either on or off... no dimming with LED's

 

My advice: hook it up, see if it works without throwin the ABS light. If it does, try adding some heavy duty power resistors in there in series till the light comes off. Those resistors will model the resistance found in a typical light bulb.

 

How heavy we talkin? and on both tails or just one? or all?

 

okay I am lurking along and I value all the effort you guys are doing to solve this.

but like 401toy says "my head hurts".

I think many of us want good results-meaning sharp looking tails and 3rd brake light, do not want any real heat generated inside the units, and just want to be sure of what will happen and what will not.

Q: Is it safe to say that not all years of our 3rd gens will necessarily require a resistor?
The impression I am getting is the 96-00s or even 96-01s may have issues while 02s definitely will not....true or false please?

Q: Is it safe to say that this will definitely not be an issue if we simply stick to a stock 3rd brake light (not LED) and use any LED tail lights sold or I am oversimplifying here?

thanks again guys for your extensive research that will benefit many for this type of upgraded look.

I would love to see a thread like "Here is my (insert year here) 4Runner with my new brand x LED tails with brand x LED 3rd brake light and no ABS light issue.

Also I am presuming that with an ABS light issue the cruise control then is also inoperable? True or false please.

I can only handle theory up to a certain point. I value most of all real world results from actual users who have had them in use for a good amount of time and mileage or both.

Also David Alexander a good seller I got my clear corners from him. Fit fine, good price and prompt shipping.

 

Answer to question one: With my research not being as in depth as I currently want it to be (Midterms) it seems that a lot of '02 runners do NOT have a problem with the entire suite. (Tail lights and 3rd brake light being led). However I'm sure if i dig hard enough, I will find a runner contrary to the rule.

Answer to question two: This will not occur on runners using stock 3rd brake light.

Answer to question three (ABS): As far as my understanding of the light, the actual ABS System is not disabled, its merely a warning telling you that your rear brake lamps are not receiving power. With that being the case, Cruise control should function normally.

Does that help?

 

Revisit to question 3: Toyota Service Manual: "If the ECU detects trouble, it lights the ABS warning light while prohibiting ABS control. At this time, the ECU records DTC in memory. Connect terminals Tc and E1 of DLC1 to make the ABS warning light blink and output the DTC." So yes, ABS is disabled.

 

most helpful Super Six One. thanks for being specific

 

So my quick diagnosis question for those trying to install so I can offer help:

Is it throwing the ABS light only when the LED 3rd brake light is connected? If no bulb at all is present (IE an empty harness), does the ABS light still illuminate?

 

I can answer the first part. Yes. It only happens with the 3rd brake light. However i don't know the answer to the other question.

 

I should imagine that it would. To the computer this just looks like a burnt out bulb.

On a sidenote: The resistors need to be connected in parallel, not series. Connecting in parallel will cause more current to flow through the circuit, simulating the higher current of an incandescent bulb. Connecting in series would only aggravate the problem.

 

So maybe this is the issue in itself. I believe on the previous page that it wasn't mentioned the configuration that the resistor was mounted. By putting the resistor in parallel, you will force most of the current to pass through the wire, not the resistor defined by electricity following the path of least resistance. Would this damage the tail assemblies as there is now a much higher current being passed?

EDIT: It seems that he did arrange them in parallel. I think that a bigger resister is necessary in this circumstance. can anyone verify the resistance there getting off the Tail Light bulb?

I found the original thread and he claims the 6 ohm resistor best models the bulb that used to be in the housing. while this may be true, we have a very bad heat issue. If we can figure out how big of a resistor is needed to dissipate the heat and still be effective in lighting the tail light, we can prevent melting our vehicles.

 

Well it wouldn't damage the tail assembly since the current is effectively passing up the light. I don't have a wiring diagram in front of me, but if too low of a resistance is used it would likely blow a fuse or damage wiring. Basically what you need to do is measure how much current the brake light originally pulled, measure how much the LED brake light pulls, and then select a value of resistance that supplements that lost current. If someone can give me some numbers I can give you a correct value

 

@rideexileex

you think you could test the voltage off your tail lights?

 

Actually what I need is the amperage. The voltage will be ~12V. Amperage is measured by connecting a multimeter in series with the light, the current passes through the multimeter and is measured.

Don't know if you've ever heard of the water analogy. You can think of voltage as water pressure in a line, and amperage as volume of water. Resistance as a kink in the line.

 

Right. I knew that. Slippin' a little bit. Just had a circuits exam this morning! so tired of electrical atm.

 

Personally I like to model voltage around 14.4 V. Thats a pretty typical value once the car is turned on and the alternator is providing power too.

This whole topic is difficult to tackle, as people have said, without schematics or any real values of current or resistance on the LED boards. I've just been trying to throw in my EE knowledge based purely on speculation of how it is 'likely wired up', which in its own sense, is a bit dangerous. It is even possible that all tail lights together are on the same circuit, I just have no idea. I'd be curious too to know if the ABS indicator is being triggered with just a 3rd LED brake light and OEM taillights. If anyone has a schematic, I think that would be the best real start...

Also, does anyone know how the ABS trigger is designed? I'd still like to know if people are getting ABS lights if nothing at all is plugged into the 3rd harness. I almost feel like going and doing some experiments of my own, even though I'm not doing LED's at all on my own rig...

 

Well, after digging online... this at least explains why the 02's dont have any problems:

http://www.ncttora.com/FSM/1996/SIL/...emci/026sl.pdf

 

This also applies to the 02's, but might help... I'm just posting as I think...

http://www.ncttora.com/FSM/1996/SIL/...b/cic12494.pdf

 

Ok... I know it was only a few minutes of reading, but after looking at those schematics/diagnostic sheets for the 02, it says that there is a short circuit detection system that can trigger the ABS light, which in turn disables the ABS system entirely. That is the only thing that I could find that linked the brake lights to the ABS system.

The fact that people reported successfully turning off the ABS light with a 6ohm resistor in parallel with the LED 3rd makes me think this:

The resistor in parallel guarantees a full voltage drop from the power to ground, which would satisfy the 'short circuit detection'. Depending upon how the LED's are wired and the type of LED's used, it doesn't always guarantee the entire voltage will drop. In our circuit models, we often model a .7 to 1.4 voltage drop across each LED wired in series, which again would depend upon how many LED's are wired in series (voltage times number of LED's should = ~12V). It could be that putting a power resistor in front of the LED board would help drop more voltage infront of the LED board, and after passing through the LED's, be closer to 0/ground. I hope that makes some sense...

So in essence (in speculation)... someone try a power resistor in series before or after the LED board and tell me if it works....