-   ZJ Grand Cherokee Forum (
-   -   LED Conversion not powering up?? (

341012 03-12-2012 09:53 PM

LED Conversion not powering up??
I'm at the end of an LED conversion to my stock tails, but i've hit a wall. My tail light wires will not power up the lights. I;ve found a writeup on someone who did a similar diy project, who said the fix was in the LOM; problem is, the LOM shown is not the same at all.

I was going to try maybe some positive trigger relays? but
1. I dont want 6-8 relays per light
2. don't know if it will work and am sure it would be a waste of time

Any ideas would be helpful, here's a link to the post that I found; I'm going to keep searching for something.

341012 03-12-2012 11:04 PM

So i got my tails to work, but now my turn signals are rapid-flashing. I would rather alter the combination flasher relay than purchase one i don't know will work. or any other fix will work too!

I found this but i'm not as familiar with this stuff as i'd like, so maybe if someone has a dumbed down solution?

Again, any help is appreciated

gactech 03-12-2012 11:17 PM

You need a resistor for the flash to return to normal speed. Less load faster speed. Like if 1 turn signal is burned out. Use an ohm meter to measure the old bulb and put the resistor in
Line on the hot side of the wiring. Should solve the issues.

341012 03-12-2012 11:21 PM

that will basically bump some power back to the source? I know resistors only go one way, but thats about all i know about resistors. once i find the ohm value, what direction do i put it in

341012 03-12-2012 11:26 PM

also, i just got a multimeter a little while ago, but really dont know how to use it. ive been told to put it on the the setting with the ohm symbol and thats it... but how? if its a single pole 1156 bulb, red to the bulb input and black to the side for ground?

ratmonkey 03-13-2012 12:40 AM

Buy a digital flasher unit.
You're making this overly complicated.

341012 03-13-2012 02:08 AM

ya i figured, just trying to get it done and learn in the process. already decided to get a digital flasher unit; hooked everything up again (already hooked up once to test) and now.. of course.. more issues. diodes burnt up on the parking light circuit for some ungodly reason (couldnt find grounding issue) now the brakes wont work either. hoping i didnt blow the parking light relay in the process.

Gotta get up early, back to the drawing board tomorrow night.

thanks for the input

gactech 03-13-2012 09:55 PM

Ratmonkey is right Digital flasher is easier. Resistors don't matter. Diodes matter. I'm an avionics tech an I always go into over kill mode when it comes to wiring and trouble shooting. :-)

david4127 03-13-2012 10:14 PM

You should do a write up as fad as what you did to resolve any any issues I am waiting for my led tail lights should arrive in a few days

341012 03-24-2012 06:16 PM

alright time to bump this for more issues.

Bypassed the LOM, Installed the electronic flasher and I had it working awesomely... for about 2 days. There doesn't seem to be any issues with any of the wiring that I can find, but now the Drivers side parking light will not power up. I'm guessing there is TOO much resistance, but its only 2% ? the pass side seemed to be having no issues, but will now flicker when activated (only when its pulsing, like the output from the alarm when its being unlocked, the parking lights are supposed to flash twice, but will sometimes be spiratic).

this is how its wired up
brake - diode (to prevent feedback) - LED
Parking - resistor - diode - LED

these are both going to the same power wire from the outputs , sharing a ground.
If I bypass the resistor and connect straight from the output to right before the diode, then it seems to work... but then i lose the fact that its dimmer, which loses the point of having parking lights!

In my one peice headlights, it has an LED strip with a diode on the power wire, a resistor on the ground... but im not sure the purpose of a resistor on a ground? maybe thats what im missing...

Who knows, I'm regretting doing this conversion, as the ole' ZJ has been MIA for about a week now and I really want to friggan drive it!

Thanks in advance to any input.

Oldfrog 03-24-2012 07:01 PM

The resistor to ground is to put more of a load on the circuit, emulating normal bulbs.

Without actually measuring it myself, the regular lamps pull xx milliamps, via xx resistance( ohms) @ 12 VDC and this causes the flasher to heat up to a certain temp and flash properly. When you installed the LEDs in place of the bulbs, you decreased the amount of resistance in the circuit, thus not pulling enough current ( milliamps) to activate the flasher properly.

The company who sold you the kit evidently measured the total resistance in the circuit with and without the LEDs and added the resistor to provide the extra resistance....and therefore, current ( in milliamps) to make the flasher work properly.

Now have had the benefit of a $50K Miss. State EE education...( which I havent used in 35 years). So at least someone got some use out of it. :)

341012 03-24-2012 07:29 PM

well that answers my question as to why a resistor is on ground....

The LED's in the headlights are only for parking lights, not actually for flashers, so it doesnt sound like there is a necessity for it.

am I correct in assuming this would not effect my rear tail light issue?

Oldfrog 03-24-2012 07:45 PM

I'd have to see the entire schematic to know. Still they are adding the resistor in order to put the proper load on the circuit. What else depends upon that circuit functioning as it was designed, I have no idea. It may very well affect the TL issue because it's obviously not just an old style ( 1960 type vehicle) set up.

341012 03-24-2012 07:56 PM

The resistor on ground was more of a 'maybe this has something to do with my issue, so ill check it and throw it in here.' Seems unrelated.

Im thinking I just need a different resistor but dont know what size or if thats right. the ones i have on there are 260 ohms 2%. i got the specs from a manufacturer of LED tail lights, but i dont know how to check ohms needed and am unable to find the information on the internet. Either way, stab in the dark...

dusterdude 03-24-2012 08:18 PM

I admire your persistance,but this is an awful lot of trouble considering this is a jeep and not a hoopdie

The time now is 09:52 PM.

Powered by vBulletin Version 3.8.8
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.

User Alert System provided by Advanced User Tagging (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.