Headlight Bulb Tech Tip

Load Resistors & Canbus Decoders
HE-LR Load resistors and decoders
When upgrading to LED bulbs on newer vehicles, it is important to balance the circuit so
that the LED bulbs are not mis-detected as blown. This issue is caused by the reduced
current draw and circuit load that the LED presents to the system compared to the
factory filament bulbs. If this error occurs, some of the common issues that appear are a
bulb-out warning light on the dash, a check engine code, and in some cases no light
output due to the vehicle shutting down power to the circuit. All of the LED bulbs in the
Heise line have special circuitry to prevent these issues from occurring; but due to
the variety of requirements by different vehicles, occasionally additional parts are
needed to balance the circuit.
LED bulbs have two different part options to balance the circuit, and can be used
independently or in conjunction.
Canbus decoders (HE-xxxxD) are the go to staple for balancing the circuit. They are plug
and play, and are installed in between the vehicle and the LED bulb (one per bulb). Heise
offers decoders for all bulb sizes carried in the line.
Load resistors (HE-LR) can also be used to balance the circuit. They are installed across
the positive and negative leads of the light bulb. The load resistor is not directional and can
be installed either way. If being used along with canbus decoders, the load resistor is placed
between the vehicle and the decoder (one per bulb). Please note that load resistors can
become hot during use and should be mounted to a solid metal surface to prevent damage
to wires or plastic parts.
Canbus decoders
Load resistors
LED Bulb
Canbus Decoder
Load Resistor
Vehicle
04/21