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.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).