LED 3157A bulbs need resistor?

[jaywish]

Assuming I can find a nice LED bulb which shoots more light forward than the standard 3157NA will I need some sort of resistor setup to have them flash properly?
A better way?
Any bulb recommendations?

I am experimenting with LED headlight bulbs and one thing I see is that I would need to up the running/turn 3157A forward output so it does not get washed out by the brighter headlights.

When I am done playing around with the 9007 headlight bulbs & 3157A I will post up exactly what I did and my $0.02.

Jay

[RubberCtyRauder]

yes, you need resistors, electronic flashers work, not sure how it incorporates with lcm

[jaywish]

When you say electronic flashers work do you mean if I use electronic flashers it will work without resistors? I never checked but I figured the flashers would have already been electronic in an 03. No?
Actually I just ASSumed that was all in the LCM.

[RF Overlord]

It IS all in the LCM, but the LCM circuits are designed to see a certain power draw from the correct number of incandescent bulbs. When you start changing to LED, the power draw goes way down and the LCM thinks you have a bulb out and does the fast-flash thing. There are external electronic flashers available for use with LEDs or you can use the resistor setup, but resistors are very inefficient and get quite hot.

[jaywish]

Yes I was looking at the heat output of the resistors and thinking of the waste as well as where to mount it without putting extra holes in the car. She has no extra holes as yet.

I will look around about the external electronic flashers.

[fastblackmerc]

I have nice LEDs and an electronic flasher.

[justbob]

yes, you need resistors, electronic flashers work, not sure how it incorporates with lcm



Bypasses the LCM. Cut the WH/R and LB from the multifunction switch anywhere between the MFS and the LCM and route them to a 2 prong electronic flasher.


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[jaywish]

Based on the recommended cut and jump & relating to the turn signals and flasher system & looking at the wiring diagram I guess the LCM just provides the flash and hyper flash functions?

Using an electronic flasher seems much better than using resistors. This would allow all 6 (?) 3157 & 3157A turn/brake/running bulbs to be converted to LED. Plus you save the electricity instead of having to burn it off in heat which while not significant in terms of economy just seems more elegant as you don't have 4 or more hot resistors to place safely around the vehicle.