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XJ LED Taillights

Help. I am being driven nuts by my jeep. I have a 2001 Jeep Cherokee XJ/ I replaced my turn signal and brake lights with LED bulbs and they flashed way too fast. I then bought a LED flasher unit that is designed for LEDs (EP27-L) since I was told that there is no such thing as a heavy duty flasher to replace the stock one. That cured the flashing speed problem and the lights work fine now. I really like the way the LEDs look.

Now the problem - Today I plugged in my utility trailer and for some reason the left turn signal causes both tail lights to flash. The right turn signal works normally. Brake works ok as does the running lights. The trailer wiring is ok and bulbs are fine. Checked the trailer ground and its ok. Checked the voltages at the connector and when the left turn signal is on there is voltage at both left and right turn connectors. When the right turn signal is on, only the right connector has voltage. I have a factory installed tow package and everything worked fine before the LED conversion. And the question is..... What could cause this and how do I fix it? Any ideas would be appreciated.

John C.

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caps
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The first thing I would try would be to go back to the stock flasher as that is what was changed before the problem came up.

Dick

Reply to
Dick

I'd look at the tail light bulbs on the trailer, or perhaps the grounds at the lights themselves(not at the plug).

-- Old Crow "Yol Bolsun!" '82 FLTC-P "Miss Pearl" '95 YJ Rio Grande BS#133, SENS, TOMKAT, MAMBM

Reply to
Old Crow

That was my thought and when I saw that the trailer used the chasis for the ground, I installed a wire from each lights ground to the connector/chasis ground point. My jeep has one of the factory installed large round connectors and I use an adapter to connect the four pin connector for the trailer. I though it might be the connector adapter but I tried another one and it made no difference. It is not the trailer lights. When I measure the voltage at the Jeep connector, the left turn signal applies voltage to both the left turn and right turn pins on it. The right turn signal works as it should. The lights on the jeep seem to work as they should but the signal at the connector is wrong.

John C.

Reply to
caps

If the factory tow lighting on a 2001 Cherokee is anything like the same on a '93 Grand Cherokee, the wiring is quite complex. It involves a number of connectors and 3 relays. I would get a copy of the factory service manual to do your failure diagnosis. Without a schematic of that system you are really shooting in the dark.

Dick

Reply to
Dick

If all the wiring is intact, the turn signal/dimmer switch assy. is where it all "Y's" together...

Reply to
Jon

Ok, I'm a little closer to zeroing in on the problem. I pulled all 13 of the LED bulbs and put the stock ones back in. Left the electonic flasher unit in since it is more trouble to replace. Everything works as it is supposed to. I put the LED side marker and top brake LED back in and everything still works ok. Don't have time today but I am going to put the LED lights back in one at a time until the problem re- appears.

John C.

Reply to
caps

caps wrote in news: snipped-for-privacy@p77g2000hsh.googlegroups.com:

That may be a current draw issue. Too little current draw can stop the flasher unit designed for higher currents.

Reply to
Nobody But Me

caps wrote in news:1181947028.550152.74450 @k79g2000hse.googlegroups.com:

I would suggest you add up all the current draws necessary to run the solid state relay switches and see if any of the loads draw too/much/little load on it. If theres a range specified for this device, check to make sure it is within the specified load.

Since filament lights normally draw a much larger current for the normal switch/flasher unit to operate properly it makes sense that a solid state flasher unit works for the much lower load current draws of the LED lights. Perhaps there is a tolerance of current which the device is unable to handle outside of the current draw it is designed for.

Reply to
SneakyP

SneakyP wrote in news: snipped-for-privacy@hamsterserver.local.127.0.0.1:

When you replace the LED bulbs for troubleshooting, I would also suggest a shunt resistor in series with these LEDs to simulate a more realistic filament bulb current draw. It's coinkydoink, I know, but this sounds more like a mismatch between the flasher unit (driver designed to drive higher current bulbs) and the lighting circuit, with LEDs - drawing a much smaller current (the shunt resistance should increase this current).

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SneakyP

innews: snipped-for-privacy@p77g2000hsh.googlegroups.com:

The flasher unit is an electronic one and is supposed to work with either LED bulbs or Incadescent. It works fine with the regular bulbs. I did some testing on one of the LED brake lite bulbs. Its one of those kind that has 25 small LEDs with some sort of electronic circuit in it. Its a replacement for a standard 3157 dual filament bulb. I found that the bulb does not have two separate electrical paths like a filament bulb does. The LED bulb is non-polarized and you can apply 12V to ANY two connections on the LED bulb and it will light. Three of the possible six connections cause a bright beam (Brake) and three cause low beam (Running light). I'm thinking that maybe I can put a couple diodes inside the bulb housing to polarize them and prevent the electrical cross connection at the Positive side of the circuit. This would give the same effect as having two separate filaments - I think.

John C.

Reply to
caps

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