led autostart problems

I have a compustar 2WSHR (module CM6200)remote starter installed in my 1990 Chevy Suburban and just recently upgraded all my dull dim stock light bulbs to LED bulbs.My autostarter was installed a few years ago along with HID headlights and LED front marker lights and I just switched over my rear tail/brake/turn signal to stock 1157 socket LED`s and now my autostarter starts my truck but shuts off after a few seconds,i put the stock 1157`s back in works fine. I have found out after some research that the LED`s have to much resistance and is shutting down the autostart prematurely.I thought installing a relay to simulate the brake pedal would solve the problem. I unhooked the brake input (lt.blue wire) from the pedal and attached it to pin 30 on the relay, then I grounded pin 87a and pin 85 to the chassis and applied constant power to pin 86 from the fuse box. My question is do I need to reattach the wire from the brake pedal to the same relay or am I missing something else,

This reminds me of another of my round tuits... (A {cruise-control?} product website posted a crap solution re similar.) Ideally find out what voltage is required to pull the sensor/wire low, and what current or resistance - ie, what is the input impedance? Then add a suitable resistance in parallel to the LEDs (ie, the RS module's interface terminal/wire and GND). The problem is that the LEDs do not GND their input - ie, they have a fwd voltage drop and the RS etc needs to be pulled below a certain voltage to sense that the brake (lights) are NOT on. Without enough pull-down current, RSs and cruise controls etc think the brakes are ON and hence disengage etc.    An SPDT relay triggered by brakes can work (ie, 30 to the lights/LEDs & RS input; 87a to GND; 87 to +12V) but I have read NOT to connect that module interface direct to GND tho that was from the aforementioned crap site and afaiRecall their relay solution contradicted that. IMO a resistor is far more elegant.

I found out the quick fix didn't work(the relay),the most it did was deactivate my brake safety switch so the RS wouldn't shut off until the allotted runtime was satisfied. I think I understand what u mean by the voltage drop and the LED`s dropping their voltage when the brakes are not in use,would you be willing to give me the dumbed down version of how to test for the input impedance, the common voltage for the RS it would seem is 250 mA if that helps at all(im fairly competent with a multi meter)and which resistor would be best for my application.

Trial and error.... I'll paraphrase... When the brakes are NOT on, that sense line is 0V (GND) since the brake bulb filament is a short to GND - ie, it connects the line to GND. It's an 'absence of GND' that tells the module that the brakes are on. (Hence disengaging cruise controls, and apparently your problem.) LEDs mean an absence of GND due to their voltage drop. As to what resistor is needed... We know that a ~4 Ohm or 2 parallel 7 Ohm resistors will work since that's the equivalent of 2 stop bulbs. [ R = VV/P = (12V x 12V)/(2 x 21W) ] One 7 Ohm should work unless module designers thought it was a 'feature' to have the module disengage if one stop light blows. Problem is that we need 7R (Ohms) at ~20W which is big, expensive, and a lot of heat (ie, about the same as the original bulb which is what we are imitating). In practice it's more likely that the module can work with a far higher resistance. Internally it will have some pull up resistance to keep it at +12V. The stop filament then pulls that low (ie, to GND or 0V or near 0V eg 0.7V or 12V or 2V etc). Such pull-up resistor are likely to be 1k or higher (since we want to limit resistor ratings/sizes to typical 14W or 1/2W types). They might even be 10k or higher. It's a voltage divider... It's a voltage divider comprising the module's pull-up resistor and the filament resistance. (eg 1k or 10k etc with 7R or 14R etc.) Now, assuming it's 1k and it needs to be pulled lower than (say) 0.7V, that means a (clink zap boom kerchunk...) 47R 5W resistor. But maybe a higher resistance will work. If you have resistors on hand, give them a try. IMO you want as high a resistance as possible (only for less heat and hence a smaller sized/Wattage resistor), but it must be low enough to ensure proper operation. Note that the minimum value resistance that can be used depends on its Wattage - eg: 1/4W 820R 1/2W 390R 1W    220R 2W    120R 5W     47W - where 'R' means Ohms (Ω) ... and the above are based on preferred resistor values and assume a voltage of 14.4V (the resistor is across the +12V supply when the brake switch is closed). Test first using bulbs?.... Keep in mind that you can try first with a stop bulb (21W => ~7R), a tail bulb (7W?), dash bulb (2-3W). If a 2W dash bulb works you know a 120R 2W resistor should work. A 3W bulb is between 56R to 68R, but that would mean (say) a 56R 5W else 2 parallel 120R 2W resistors.    Sorry if that's too much verbiage but I've included assumptions, justifications, and various test & permanent methods & sizes/ratings. Even then, a lot of detail/theory has not been given. Please ask if you want a better breakdown (or just treat each section in isolation). Otherwise maybe it narrow down by saying what you have available, or what any testing shows (eg, it works for a 7W tail bulb not a 680 Ohm 1/2W resistor).