LED turn signal damage.
 

Hi all,

I recently changed the turn signal bulbs to LED and used resistors to prevent the hyper flash.
Yesterday I was told by an auto electrician that Nissan use a Body Control Module to control all of the electrics and that the resistors could quite easily fry the module which would then cost $1500 - $1600 to replace.
He said that this could happen at anytime, a week, 4 months a year or years after fitment.
I've never heard of it happening before but was wondering how true it is and why it does it?

Could anyone shed any light on this?

As long as the resistor is the proper value, you shouldn't have a problem.

LED lamps have a higher resistance than incandescent lamps and so do not pull as much current. The BCM senses the current when the light is turned on and goes to fast-blink mode if the current is below some threshold value. The resistor in parallel with the LED reduces the resistance of the circuit causing the current to rise above the threshold.

Thanks for that SouthArk.
My only concern would be that the resistors are a higher wattage than the incandescent bulbs (50w), is this possibly too high for the BCM to comprehend for the turn signals and hense the fry up ?

The wattage rating of resistors indicates how much power the resistors can dissipate (as heat) and does not effect their electrical performance. Nothing wrong with using a resistor with a higher wattage rating (as long as it will physically fit). As long as the ohms are right and wattage is equal to or greater than needed, you'll be OK.

Hey, thanks once more SouthArk.
You are a legend on this forum, always one of the first to help out others, and I for one really appreciate your help.
Keep it up my friend.

The load resistors that are sold to prevent 'hyper-flash' are of the proper value and won't harm the BCM. Sounds more like a case of 'auto electrician' has absolutely no background in electronics. :p

Hi Ghostvette,

Thanks for your input.
I thought the same thing at first, but then when he specifically mentioned that the wires leading to the turn signal bulb on the 370z are thinner than usual vehicles, is when it got me thinking that an auto electrician might know what he's talking about.

That's a clear indication that he's clueless. There's no difference in wire size on a Z as compared to any other vehicle. :confused:


Any way, make sure you have a good connection on the load resistor and it's installed with some kind of a heat sink on it. They do tend to get warm enough to melt insulation if they are laying on the wiring harness. I put mine on a piece of 1/8" aluminum with heat sink compound between the resistor and the block, then covered the whole thing with heat shrink. No problems so far. Oh, and you only need one on each side.

As per Ghostvette, your "auto electrician" doesn't understand how electricity works. LEDs, since they have a higher resistance than OEM incandescents, allow less current to flow (which triggers fast-blink mode). The resistor in parallel with the LED lowers the circuit resistance, raising the current to something closer to what it is supposed to be.

And the resistor will get HOT. Some people add a heat sink; some people bolt the resistor to the frame or a metal body part for a heat sink. Keep away from any plastic parts.

Dogdamn.. too technical for me. I just use stock bulbs and never had a problem.


Never understood super bright plate lighting too.