New LED Lights - Not enough power to run 'em.

[sixpantsmaloney]

My old tailights were flickering and dim so I decided to be smart and replace them with LED lights.  I figured they'd be brighter.

They don't work at all unless connected directly to the battery.

So I checked the voltage coming out of the wiring harness (one of those eTrailer jobs where you just plug into your existing light sockets).  I'm getting the following:

Turn Signals : 10.5vdc
Brake Lights: 11.4vdc

Didn't check amps.

I suspect that there isn't enough power for the lights to work.  eTrailer couldn't give me any voltage requirements for the lights.  They told me to run AUX power directly from the battery to the harness.

That brings up a few problems:

1) Which of the 3 wires would get power?  Seems like all of them.
2) If I run power from the battery, I've bypassed the switches so they should be always on.

Here's the specific parts I'm working with (links to eTrailer):

http://tinyurl.com/matrix-harness

http://tinyurl.com/matrix-lights

And here's what they told me to buy:

http://www.etrailer.com/p-118151.html


So here's my conclusion (tell me if you agree): my harness doesn't support aux power which means I have to buy a new one.  If I could replace all the vehicle's tailights with LEDs then maybe I would have enough left for the trailer.

What a big pain.  But I had to do it.  The old lights were just too dim and cars weren't happy with me.

Thanks for reading.
Brian

[Chuck S]

10.5vDC is a dead 12v battery.  Did you check voltage with the trailer connected to the tow vehicle and the engine running?  10.5v could also be caused by a series of filthy connectors -- flickering and dim is a giant hint this is the case.  Measure it at the truck's outlet.  Engine running.  Should be 13.7v.  Start cleaning connectors and work your way aft.  Broken, intermittent wire is possible.  Bad ground -- the white wire -- is often the case.  Check where it screws to the frame.  The ball and coupler act as a ground too, but not as good.

4-wire "boat trailer" wiring harness is dirt simple.  White/Ground; Black/Tail & Markers; Yellow/Left Turn-stop; Green/Right Turn-stop.  Same color codes on your camper.

-- Chuck

[kfriceman]

Your incandesent lamps require way more power than a LED lamp, that is why they are so effcient.  Follow Chuck's recommendation and I'm sure you'll the source of the problem.

-Kevin

[sixpantsmaloney]

The grounds are all good.  How do I know?  The trailer lights work when run straight to the battery.  So that clears everything on the trailer down to the harness.

The car ground is good because I ground away all the paint and screwed the ground into the unibody.

I will go ahead and clean and check all the connectors.  That is indeed the most basic step.  I should've started there.

I'll try it all again with the car running as well.  My experience with cars has been over 14 volts (at the battery) with the car running.

Man... I thought this would be easy given the low draw of the LEDs.

[sixpantsmaloney]

So here's the follow-up:

Cleaned all leads.

Checked continuity on all trailer wires, grounds, etc.  Everything checked out.

Now it gets weird.  I tested the car harness.  I was getting 12-13vdc when the car was running.

I plugged in the harness, checked the voltage at the trailer light, I was getting 1vdc.

Then I tested the trailer light voltage but I grounded to the car and I jumped up to 12-13vdc.  So it's a bad ground, right?

Wrong.  Several minutes later the trailer lights were at 12-13vdc with the original ground.

So I did something scientific: I connected the multimeter to the car harness again and started whacking the adapter's junction box.  Voltage started bouncing all over the place.

I'm thinking that I just ripped all the wiring and lights off a trailer that was actually fine - it's the wiring adapter that's going crazy.

I can't replicate ANY of these problems which makes it all the more difficult, confusing, and frustrating.

I mean, we're dealing with DC current here, not rocket science.  I've got 4 beautiful bare-metal grounds with soldered connectors.  My continuity is perfect.

It makes me sooooo tired sometimes.

[Chuck S]

"Adapter junction box?"

-- Chuck

[sixpantsmaloney]

Best term I could come up for.  The part of the wiring harness that's a black box that all the leads come into and the wiring harness comes out of.

I had a hunch a took too much creative license with that one.

[Chuck S]

Wasn't sure if you meant something on the truck or trailer.

I have this junction box under my trailer.



-- Chuck

[dodge6564]

the post office uses the led brake and turns on the postal trucks, they are not bright when the truck is not running- we were told that they want 13 volts to run.  there is a big difference with the flashers with the  trucks off and on.  jeff