In the older days, the turn signal blinker box was voltage and load sensitive. A change in load (i.e., burned out bulb) would make the lights blink faster, slower, or not at all. That way you knew a bulb was out.
I suspect you can remedy the situation by purchasing a replacement blinker designed for towing a trailer. They are designed to ignore load. However, I am not sure this is the case, or if the blinker module is replaceable in the RS.
ok this thread IS old but I'm having the same problem... What do I do to get these LED bulbs to work? The signal-click is faster when I plug them in but they dont illuminate... any help would be appreciated! They are the 1156 type LED bulb which has the pegs at the same height like the stock bulbs do, the 1157's have staggered pegs. HELP MEEE!!
For anyone who's interested, I finally figured this out...
Since I work in an electronics repair shop, my materials (though none were actually needed) were free.
The short answer is polarity, but this only partly solves the problem. If you pull the terminals out of the plastic harness (white end) and switch them, your bulbs will flash but, they will flash 2x as fast when using them as signals and normal speed when using as hazard flashers. To remedy this problem, either add a 5-6ohm 10+watt cement resistor to bridge the leads and it will put enough draw on the circuit to simulate a filament in an incandescent bulb. Or use the load equalizers from http://autolumination.com/equalizers.htm. Either way it will definitely generate some heat so heed the warning to avoid paint and plastic. LED bulbs draw so little current, that the car thinks it has a bulb out and like James suggested it blinks faster to indicate that. You may be able to slow the blink back down by putting LEDs in all 4 corners and your sidemarkers but there is also a possibility that cumulatively the LEDs still wont put the expected load on the signal circuit and they will blink faster. Most importantly remember that the LED bulbs have opposite polarity than the wiring, so switch it.
This installation diagram is from that site that sells the load equalizers, and it explains what resistance you need based on how many bulbs you are installing.
those splice-in clips are great doodads for electronics fanagling
Right now my signals are just LED in the fronts and still the stock bulbs in the rear so I'm not quite done tinkering since they blink fast.
I'm tempted to pick up some LED lights to get rid of the ugly amber, but I just depise the idea of putting a RESISTOR in parallel with it for no reason but to draw current. (i.e. waste energy and generate heat)
So I hunted around for a flasher unit that used TECHNOLOGY instead of an old-school design that relied on high current draw.
Most of the stuff I found is intended for auxiliary lighting on cop cars with super-fast blink rates and wacky patterns. But this one looks like it MIGHT fit the bill: http://store.sirennet.com/fsfa3-sb.html
It LOOKS like it has the same spade-connector layout as a factory flasher unit (from old GM vehicles; I haven't been inside my Suby fusebox yet), and supports up to 10Amps (but presumably blinks even if there are LESS than 10Amps being drawn, which is the goal here). My hope is that this would handle the combination of front (LED) and rear (incandescent) bulbs.
But I can't be sure it'd work without at least a pinout of that flasher... and the thing is over $20.
rskm1 that flashers pinout is identical to the standard wagner flasher
And you are correct it should flasher no matter the draw on the 2 outputs unlike the standard flasher. The main question is what are cars use for the flasher, I've never had to replace mine. And the standard flasher(537) doesn't flash twice as fast when a bulb goes out, it normally slows down or doesn't flash at all....
The cheapest route would be to use a resistor like Ninja mentioned.