Re: LED light nightmare!!!

Gar wrote:
Thought I knew everything about everything.. then this..

I have my toad wired not through the toad wiring, but a complete separate harness from the RV to a single 2 stage bulb [1157] on the left rear and right rear..

This has been a very satisfactory system.. so... I thought I'd improve it a bit.. :)

I bought 2 1157 LED bulbs.. $12.50 each.. gulp... put em in the sockets and found out they run on no energy at all!!

Yup.. hook a battery neg to the ground pos to the yellow..[left] and *both* Sides light up.. bright on the left and dim on the right.. same thing happens in reverse hooking power to the green..

The opposite side LED must get enough power from the neg feedback to light..

I could not make these bulbs work properly.. no matter what single wire I gave power to.. green,yellow or brown I had both bulbs lit..

Put old 2 stage 1157's back in and all is normal..

Wasted a lot of time and have now got it back as it was originally..

Anybody want to buy a couple 1157 LED bulbs?? <g>

What was going on?? I can't figure it out.. weird...


OK Gar,
It is nothing you did.
Get a hold of the supplier and make him correct the issue (unless they are Chinese parts from E-bay and then you are pretty much stuck).
This is going to be hard to explain with out drawing diagrams (engineers can't talk without drawing).
LED 1157s are different than incandescent 1157s in at least two ways, but the big one here is that the "bulb" uses a short string of LEDs for the low level and a long string for the high level. In many designs, the long string power also feeds the short string so both are on with the brake light power applied.
Therein lies the problem. These units don't have the blocking diode to keep the power supplied to the short string from backing out into the marker light circuit.
If you really want to keep them, all you really have to do is get the toad diode packs that are out there, or get two silly little diodes to put in the extra harness where it splits for the taillights.
I've run into other strangeness in LED conversions. Some just a result of the very different operating current and some just because the original manufacturer of the vehicle took a "cheap assed" short cut that should not have been done the first time.
Matt Colie
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