brake light flasher

Hey all,

Im trying to install a brake light module (flasher) that basically duplicates a brake light pattern similar to an ambulance.

the vehicle is a 2010 Toyota Tacoma that has a combination tail/brake light which is LED from the factory.

I'm thinking the problems im having are due to some sort of PWM which i have little experience with.

I can install the flasher on the 3rd brake light no problem, a "hot with brake applied" wire will trigger the high mount brake light perfectly, but when i try in on the entire brake circuit on the left brake light will flash then light up the way its supposed to. the 3rd and right light wont light at all

The installation is to cut the +12 from the brake and wire in the modulator. If I apply +12 to the harness wire I get the above results, if I apply it to the brake switch side I get the high and 3rd light, but they don't flash.

Im assuming my problem is due to some sort of PWM in the combination brake/tail light which is factory LED.

I tapped into the blue wire (brake light wire) which shows +12v when the brakes are applied and 0 other times, but I tapped into it in the drivers kick panel as opposed to the brake pedal switch (cant see how that would make a difference but you never know).

Any thoughts would be greatly appreciated.

I guess besides the pwm part of the equation, there might be some reason that the relay has to be wired into the actual brake light switch, but I can't see why.

I have the module hooked up to 3rd brakelight now and it works perfectly... 2 flashes then steady brake light. +12v is the same anywhere along the line right?

I have the module actually installed behind the third brake light and nowhere near the braklight switch.

very confusing with the whole "combination" led lights.. im sure if the the brakelight was actually a separate bank of lights this would no problem.

Are all three brake light signals fed from the same source? It sounds to me like maybe all three lights have dedicated power feeds. This would be true if the turn signal was somehow integrated in to the combination lamp circuit.

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Kevin Pierson

the turn signals are a separate regular bulb on their own circuit. The tail and stop lights are on the same circuit and the same LEDS. I'm assuming there is some sort of PWM going on for the combination circuit.

From what I can tell the same blue wire feeds all 3 brake lights, but I am not entirely sure.

Backup and turn signals are regular bulbs and tail and stop lights are led, the same LEDs get brighter when you hit the brakes (thats why I assumed the PWM).

I have a feeling that the module might not work with a circuit like this, it might only work on "stand alone" circuits.

I figured I would ask here before tying to explain this to the manufacturers tech support

Are the OEM tail/stop lights one or 2 wire (excluding GND) - ie, is it one wire for the stop and one for the tail (plus the GND)?
If only one wire, the dimming is done somewhere upstream.

There are 2 ways dimming is done (ignoring the uncommon 2 sets of separate stop & tail LED types).
- PWM where there is no internal switching of the LEDs thru resistors etc,
- switching types that switch in an extra resistor for the dimmer tail brightness (or a current limiter). Usually the "switch" merely bypasses the tail resistor to put +12V direct to the LEDs.

(Note that that excludes normal LED resistors. Each LED string should have its own resistor that current limits +12V (14.4V etc) - ie, resistors as normally used for LEDs and strings of LEDs. But PWM may omit that, and so might any LED string for that matter - eg, if 6 to 7 series red LEDs; or 4 to 5 series white LEDs.)


I could probably figure out which it is from your description, but since I'm just out of bed and pre-coffee (and on the way to the shower to contemplate series protection diodes for relays LOL).


And I'm assuming it/they are not CANbus controlled etc, but straight non-data connections. (Even if resistor switched or PWM'd from up front).

Oldspark,
Thank you for getting back to me. I will double check the wiring as soon as I can. The same LEDs definately are used for both tail and stop. I would hazzard a guess that they are pwm controlled somehow as opposed to the resistor method that I have used to make my own harley tail/brake.

Assuming they are controlled up stream is there any way this module can control only the "brake" kight part of the circuit?

Possibly, or probably(?).

The obvious is for the flasher kit to energise a relay that swaps the LEDs from their "supply" to the kit output.
That may mean no tails between flashes, and it may cause light monitoring circuits to bark.

The kit output could also control the relay if the relay is fast enough. Otherwise transistor or FET switchers - either changeover like an SPDT relay, or on-off (SPST) if diodes can be used to prevent backfeed into the upstream PWM.

I found a schematic online that seems to indicate that there is a "stop light controller" in between the brake light switch and the lights. I can only guess that that means PWM...

I will attempt to splice the +12v line farther down the harness, I originally cut it in the driver kick panel which may be before or after the controller.

If that yields the same results I will have to assume that the kit wont contol combination lights. Arrrrg

The name suggests it is resistive - ie, the stop light controller bypasses the tail LEDs' resistor.

A PWM should be called tail light controller because the PWM is used to dim the fully bright stop LEDs. The stops are straight thru else maximum PWM duty cycle (99% etc).

But names are one thing, how or what they do is another.
And if it was a tail light controller, I can well imagine them calling it a stop light controller because, after all, what does it take to "control" tail lights, whereas a stop light control sounds bling, fancier, and more high-tech.

IMO the flasher can still be used - provided it is legal - and monitor circuits aren't critical (else tricked with resistors).

Implementation-wise, you may need to decide if you want tails between flashes, or dark between flashes. If the contrast is poor, I'd argue dark between flashes, but that is also dependent on local regulations.
And since you probably need to supply your own tail light control, the implementation will probably be "normal" tails EXCEPT when controlled (flashed and on) from the brake flasher.

And of course what the present system is may need to be determined, though if the control is from the front (ie, just one wire to the stop/tail), I don't think it maters. Actually neither may 2 wires - it's just a matter of knowing which wire is which.

And if the LEDs do not have their own "master" or "base" limiting resistor, we need to know that.
[ Repeating but paraphrased - usually all LED strings have their own limiting resistor to set the maximum current to (say) 20mA max per string at 12V or +14.4V etc. Either that is PWMd at (say) 30% duty cycle for tails, or a series "tail" resistor is added BEFORE the base resistor & LEDs for tail dimming, and that resistor bypassed with +12V for full brightness (brakes), or shorted out with relay contacts. ]

Check too that the LEDs are grounded and that the "inputs" are +ve voltage. Some systems could bypass a ground-side tail resistor.
Schematics should show enough detail to determine that (assuming they are trustworthy - ie, American or Jap).

Yeah this just went a bit to much for my paygrade... I might have to punch out on the whole project and just leave it attached to the third brakelight and call 'er done.

Thank you for your help however.

Don't you already have the flasher unit?

It may just be - and probably is - a relay and a few diodes that are required, and a resistor for any alarms/lamp-alerts.

Yes I do have the flasher installed and working flawlwssly on the 3rd brake light. It just seems to be getting a bit much for what was to be a very quick easy install. Basically supposed to be splice and play.

I dont know if the juice is worth the squeeze anymore.

I will try to take a little break for a few days and regroup.

I dont want to give up prematurley.

https://www.wiringdiagrams21.com/wp-content/uploads/2010/09/ToyotaFJCruiserstoplightswitchWiringSchematic_thumb.jpg

This is the schematic I was talking about, maybe it will help. I am confident that you'll be able to make more sense of it then I can.

LOL - the first thing I was going to do this morning was PM you to say I too should take a brake, I mean break. I realised that yet again I have evolved solutions based on what was originally a question, hence skipping all-important basics.

Anyhow, your link/diagram solved that. Or at least in part...

It shows a brake switch that can be used to power/control your brake flasher. (Trailer extensions for the FJ seem to be done from the switch and not the light end.)

It seems the ECM merely checks the switch for correct operation and had nothing to do with PWM etc. (There is no connection from the ECU to the lights.)


The only complications I see are the skid control module can override the brake switch and "break" the lights, and it seems to be a dedicated stop light circuit.
The skid control is easy - your controller should come after its relay (ie, between its pin #3 and the lights) instead of the brake switch, unless you don't want it to flash when under skid control.

But as to the lamps...
Are you sure the stops are LEDs? The diagrams infer bulbs. If bulbs, that could account for the behavior you described. And the 3rd or high brake lights normally being LEDs would behave as expected unless perhaps the other stop bulbs were also connected.

Also, are you sure the bulbs else LEDs are a combined stop & tail?
If so, there is nothing on your link diagram to show how they are controlled.
Hence are your stop/tails OEM or an aftermarket fitting?

You may have answered the above conclusively already - just like you had with my last reply's stupid question if you already had the flasher (d'oh!).
But yeah - let's regroup, my first-in-the-morning sessions aren't my best.
I'll get back to (confirming of) the dedicated stops and LEDs after a re-read, and additional FJ searching.

Yum - coffee time! Oh, and breakfast.

I have a tacoma, and now see that might be the wrong diagram.. arrrrggggg

The tail lights are stock and definitely are the same LED for tail and stop... they must be pwm somewhere.

I was under the impression that I had the right diagram. I have a 2010 Tacoma crew cab...

I might try to cut in at the switch later this week when I get a chance. I found a +12 in the kick panel where it was easier to work.

Same color and showed +12 onky upon break pedal depression so I didnt see a problem.

Maybe where I cut was before or after where I should have.

Doesnt make sense to me, but thats why im here to begin with LOL

Either way, I appreciate your help.

It doesn't have to be PWM, it could be resistive as I wrote. (Current limiting can also be used, but generally not for parallel strings. Besides, PWM is cheaper with a guaranteed constant drop in dimness.)


But then, you know for sure that the stop/tail only has ONE wire to it - ie, it's variable +12V feed (plus the GND being the 2nd wire that we usually don't count).


I've googled various Tacoma wiring images but have yet to download them (as well as replace my own car's steering-column combo switch... today?).

Well either way I still have to get back in there and satisfy my need to figure this out. I will see if you come up with any advice after seeing a schematic. I defer to your expertise as I said its over my head.

I am going to pull a tail light and check the wires and confirm wire colors. Should be blue for brake and green for tails white for ground.

I still feel that I tied into the blue wire in the wrong spot. Somehow it seems that might play into why it was back feeding the circuit.

Again thanks for trudging through with me.

Hang on,now you're saying it's a 2-wire - ie, blue for brake and green for tails (& white = GND).

In that case the 2 are separate...
Well... it may be the same LEDs, but it means the blue (brakes) override the (dim) tails.
That is probably done with the extra tail resistor method that I mentioned - the brake supplies +12V after the tail resistor, or IOW "bypasses" the dimming tail resistor. (I really should include the simple diagram that shows it all...)

That can explain the behavior - if the flasher is flashing the LEDs on & off, there is also the "dimmed" +12V tail feed when the flasher is off between flashes. (And that feed may be effecting the flasher circuit.)
The thing is, that is NOT an issue of tapping the blue at the wrong spot, it's simply that the tail feed must be isolated when flashing - ie, a changeover relay.

NOTE that the above just off the cuff - I haven't re-read the behavior you described in your OP. And there are many ways such combo LEDs can be set up, but being 2-wire, I doubt it is PWM.   

If it's 2 wire, then a changeover relay should do the trick...

I reckon simple tests should help...
See if both blue & green supply +12V with brake and tails on respectively, and when both brakes and tails are on. (I think the meaning of that is expressed well enough wrt English.)

Although this next may be too complex and NOT required, maybe you could also connect a grounded 12V LED (string) - maybe the 3rd brake LED - to confirm that neither blue nor green dim at any time - they are either fully on else off. That may also be possible using the DC range of the DMM (it may drop if "dimmed").
If it's PWM, the DC voltage may also drop (but not for certain), and usually the AC range would be used - ie, a changed (and maybe higher??) AC reading when dimming occurs.

[ FYI (only) - you'd expect no = 0V AC on a car's 12V DC system. But with the alternator charging, significant AC readings are usual (eg, 6VAC - 30VAC). When not charging, there should be no AC except for noise (maybe mVAC or a few VAC), but loads can induce AC - especially motors (fans) and ECUs.
What we are looking for is a change compared to the background or ambient AC voltage on each of the blue and green with the IGN on (assuming you need IGN for the brake lights) when each or both are on. But as I said, I really doubt that any PWM is involved. If so, more wires and more complex wiring up front (at the switches) would be required - ie it can be done with over 1 wire, but otherwise you need generally need 3 wires to the LEDs, not 2.
Yeah - I reckon scrap that thought. I really should delete all this crap about DMM AC testing for PWM! ]


Yeah, I think I need to clear my head by installing a modern flasher & wiper combo switch to my 1965 steering column...   Ah, cool - it's even cooler than today's predicted 29°C (which is much lower than the mid-30's °C we have been having).
Maybe I will be refreshed by tonite?

Im gonna get back into it later this week and I will let you know my findings. I will meter everything and check for drops in current.

I will catch back uo with you then.

Good luck with that switch upgrade. )