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Motorcycle LED Technical Blog by Custom LED

Posts in the 4-Way Blink Problem category

4-Way / Hazard Blink Problem on Motorcycles with LED Turn Signals

What the Heck is the 4-Way Blink Problem?

Some motorcycles exhibit strange behavior on the blinkers when switching out from Incandescent to LED blinker lamps.  You may experience what we call the 4-Way Blink Problem, where all turn signals on the motorcycle blink simultaneously - regardless of the direction you choose on the handlebar turn signal selector switch!  Basically, the blinkers behave like hazards anytime you try to use them.

What Causes the 4-Way Blink Problem?

The problem stems from a lack of restive load (incandescent bulbs) on a blinker system that was designed for incandescent bulbs - however the best solution is actually NOT to add resistors.  It is actually best to solve the problem at the source, which is the turn signal indicator lamp in the gauge cluster.  The turn signal indicator lamp is the little light that blinks next to the speedometer when you are turning. 

It is at the turn signal indicator lamp where both the left and right turn signal circuits are brought together.  Left turn circuit on one side of the indicator lamp "filament" and right turn circuit on the other side.  With the incandescent turn signal bulbs installed, the system behaves as designed where voltage on either the left or right turn signal circuits illuminates the turn signal indicator lamp.  This is achieved simply by allowing the opposite side turn signal circuit from the one activated, to function as a ground path for the indicator lamp.  The small amount of current that passes through the indicator lamp in the gauge cluster is not enough to illuminate the power-hungry incandescent bulbs, and they simply function as a ground path without lighting up at all.  When removing these incandescent bulbs and installing LEDs, you have removed this ground path - which usually leaves the turn signal indicator lamp inoperative - AND you have introduced voltage to the opposite side turn signal circuit which is enough to illuminate the super efficient LEDs.

OK, So How Do I Fix the 4-Way Blink Problem?

The pure solution to the 4-Way Blink Problem (not the simple one, but the correct solution) is to diode isolate the two turn signal circuits leading to the gauge cluster, and provide a dedicated ground for the indicator lamp.

This is done by finding these two turn signal circuit wires leading into the gauge cluster (typically the same wire colors as found at the blinker lamps themselves).  Once you properly identify them in the harness leading to the gauge cluster, you cut them and install a Diode (1N4001) in each circuit (with the gray band towards the gauge cluster) on the two wires feeding power from the turn signal circuit. You will then combine the outputs of the diodes into one of the two wires leading into the gauge cluster, and ground the other wire going into the gauge cluster.

The diodes will keep electricity from being able to cross over from one turn signal circuit to the other, but it will allow the two circuits to be combined to power the indicator lamp properly.

The following crude sketch illustrates the concept.

The 1N4001 diodes can be purchased from our website here. You will need 2 diodes for a proper install.

Dude, You Lost Me!

If installing the diodes seems too involved for you, don't despair, there is another solution. The simplest way to fix this problem is to add some resistive load to your blinker system to damp out these crossover voltages and restore the ground path for the indicator lamp. One pair of our Stage I Load Equalizers may sufficient to solve this problem on some modern sportbikes, however most bikes do require more than one pair, or larger Load Equalizers altogether. Older bikes require as much as 25 Watts to be dissipated through a resistor to eliminate this problem! 

I'm afraid it will take a little experimentation to get the right amount of load.  But, if installing one pair of the OEM blinkers back on the motorcycle eliminates the 4-way blink problem, then you can be sure that an equally sized Load Equalizer will do the same (match the wattage of the original incandescent bulb, to that of our Load Equalizer).

By Custom LED | | 1N4001, 4-Way Blink Problem, Diode Fix | Read more

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