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Keyair · 06-07-2012, 11:25 AM

Did a refurbishment of the Tail Lamps on my 1984 Motorhome...
Stock Monarch assemblies with Dual filiment 1157 Bulbs, that look just like the Trailers from the same period

Pulled the Tail Lamp Cans out, because they looks terrible...
Like this...

Derusted, primed, and chrome painted them to increase relectivity.

Put in 1157 LEDs with 102 elements, and was VERY happy with the output.

Checked they worked, white wire riveted to can body is ground, Black wire is 5W light feed and Yellow wire is 21W brake/blinker feed.

Put them back in the Motorhome, and reconnected the wires...
I get the 21W output lit when I brake or put blinkers on but no 5W light...

I tested the polarity and output with my Powerprobe 3 and all looks normal.

Swapping the stock 1157 incandecent bulb back in and all is normal again...

I do know that LED's are polarity sensative...
I am not sure what is wrong, if its a bulb issue or something is wrong with the motorhome wiring.

I have recently replaced some of the upper marker lamps that came with incandecents, and when i put LED's in them they refused to work, so I am worried that the wires are reversed there, and this might be a somehow connected.

Electrics are not my strength, so I would love some knowledge or insight!

Skater · 06-07-2012, 04:58 PM

An 1157 bulb has two conductors... does the LED have two pins on the bottom of the base? You can compare the incandescent and the LED if you're not sure what I mean.

Keyair · 06-07-2012, 05:11 PM

I understand what you are saying...
The stock 1157 has two + contacts on the bottom, and two height offset location pins to make sure the correct contacts(21w or 5w) are on the correct spots to engage the feed from the chassis wires.
The ground is supplied thru the bayonette body.

The LED in this case was advertised as a direct fit 1157 bulb.
Testing it off the M/H in the reflector with the wires it works fine.

Testing the the LED directly using a powered probe it works on both brightnesses dependant on what base contact is touched..
Bridgeing the two + contacts on the base and rocking the probe alteranates between the two brightnesses.

My gut feeling is there is something wrong with the MotorHome wiring... but I might be wrong!

ventport · 06-07-2012, 06:16 PM

Are you sure you are getting the can grounded really good? Sounds like a ground issue to me.

Keyair · 06-07-2012, 06:45 PM

Reflectors are grounded well, so if its a ground its somewhere else...

HowieE · 06-07-2012, 07:10 PM

If you are getting one level of the lights that says your ground is good and the brake side wiring is good. What remains is to prove you have the parking light signal coming to the fixture from the truck. Separate the wire you believe to be the parking lights from the fixture and test that wire for voltage while the parking lights are on. If you have voltage at that point the problem is in the fixture and most likely the contact between the bulb and the base. You can also reattach the parking light wire and test for voltage in the fixture base. If there is voltage all the way into the base there the pin to bulb connection in the base is open. Look at the base of the bulb and see if there is a difference in the height of the tabs on the bulb base. If there is add a little solder to extend the pin to a point where it will make contact with the base.

Keyair · 06-07-2012, 08:03 PM

Ok, its possible its a ground issue, but when I swapped the LED's to the yet unmodded pass side its the same....

HowieE · 06-07-2012, 08:52 PM

If you have one of the elements working I have trouble thinking it is a ground issue. You have 2 signal sources, brakes and parking, and one ground path. In order to have any light work you have to have a connected ground and you say one light works.

As for the sources, each is an open circuit until you switch it on. Your current path is then the source through the bulb and to ground.

Have you checked the parking light source as noted above for voltage at the wire at the tail light when the parking lights are turned on?

Skater · 06-08-2012, 06:08 AM

I'm not feeling the ground issue theory. A ground problem would be worse with the incandescent bulb because of the higher current, I think.

Let me think it through again: You know the sockets work correctly because the incandescent bulbs work correctly. Further we can assume the sockets are wired correctly: positive is on the bottom terminals for both circuits, and negative is on the base of the bulb, or you'd have a short circuit, or the LED wouldn't work at all (it'd be wired backwards). So that leaves some sort of problem with the LED...

Were you able to test both modes of the LED off the camper? It doesn't come on at all, right?

ventport · 06-08-2012, 06:29 AM

Look very carefully at the two contacts on the bottom of the two bulbs. Compare them to each other and where the two indexing pins are on the sides of the bulbs. If the side pins on the LED's are not in the same position in relation to the bottom 2 contacts as the stock bulbs, that could cause the problems you are having. Hope this makes sense. Let us know when you figure this out.

Keyair · 06-08-2012, 06:44 AM

The led works fine on the bench..
I will look at the pin indexing and report back.

Electrics are my weak spot.
One thing I wanted to mention.
I am using my new toy to test... a Powerprobe 3.
I do notice that when I touch the + terminals on many of the contacts, it emits a crackling sound from the PP3 speaker...

Keyair · 06-10-2012, 03:22 AM

Some of my rubber bulb bases are begining too deteriorate...

Can you buy replacements anywhere?

Dan@LED4RV · 06-11-2012, 11:09 AM

Quote:

Originally Posted by Keyair

Put in 1157 LEDs with 102 elements, and was VERY happy with the output.

Checked they worked, white wire riveted to can body is ground, Black wire is 5W light feed and Yellow wire is 21W brake/blinker feed. ............

...............Put them back in the Motorhome, and reconnected the wires...
I get the 21W output lit when I brake or put blinkers on but no 5W light...

I tested the polarity and output with my Powerprobe 3 and all looks normal.

Swapping the stock 1157 incandecent bulb back in and all is normal again...

I do know that LED's are polarity sensative...
I am not sure what is wrong, if its a bulb issue or something is wrong with the motorhome wiring.

I have recently replaced some of the upper marker lamps that came with incandescent, and when i put LED's in them they refused to work, so I am worried that the wires are reversed there, and this might be a somehow connected.

Electrics are not my strength, so I would love some knowledge or insight!

I agree with ventport. I think it is a ground. I would look at the other end of the circuit, like the converter, battery. When LEDs don't work because they are polarity dependent, and incandescents do, the incandescent light is completing the circuit by way of another circuit. When this happens with a 1157 socket/light the circuit is completed by way of the other circuit. In the case of a stop and turn not working with LEDs it is getting completed by way of the running light circuit.
One time I had a problem like this and ran a wire from all three cans to the frame of the unit. The 3 white wire grounds were not making good contact, and it was a major pain running the wire inside of the wall of the Airstream. I first tested this theory by running the wires outside of the unit. I attached all three cans to a jumper wire and hard wired to the frame.
In this case, since the running lights are not working I don't think this will fix your problem.
However, since finding a bad ground on the other end (converter/battery) will be a lot of work, I would run a good ground on the outside of the unit (3 cans to the frame) just to be 100 percent sure. That is pretty easy compared to.

SteveandJo · 06-18-2012, 06:50 PM

Hi, we are new members. I (Jo) don't understand exactly what you're dealing with, but words and phrases in your discussion sound similar to other's problems: Grounding, vehicle error, trailer error---and it's not errors in any of these, it's the mix between technologies. We're dealing with a new 25FB flying cloud hooking up to our Mercedes GL550. Electrical output from the GL (and it has happened with Land Rover, VW/Audi, too) and the lower power draw from the trailer's LED running lights, etc. cause the running lights to blink as if we turned on hazard lights. The solutions being considered are installing load resisters on the 7-pin connection or more than one incandescent light bulb inside the trailer to take up some of the power. Do a search in this forum using "Mercedes LED" and see the discussions and options. Someone else told me that in order to change incandescent bulbs to LED on his motorcycle would require installing resistors, so he opted to not change the bulbs; similar comment in one of this forum's threads. Hope it helps; good luck with whatever.

Forgot to mention that there is more information in other discussions about where to install resistors, such as in the rear lights of the trailer (i.e. inside the cover if there's space)....

Keyair · 10-19-2012, 12:30 PM

Time to update this thread and ask some more questions..

Further to my tail lamp issue, I figured out why the upper marker lamps would not work when I put the LED's in
They are made by Grote...
Her is a view of the internals... complete with incandecent bulbs.

I already mounted the rear ones, and if you notice the Ground connection is handled by the tab under the mounting screw...
The Incandecents worked great, but when I swapped in the the LED bulbs, they would not work.. so I swapped the incandecents back in.

Now I have the front markers on the bench and wanted to figure it out.

Connected the body to a ground, and the wire to +.
The Incandecents worked fine.
Put in an LED, on one side... Nada... Nothing, but Incandecent was working fine.
Now, I know that LED's are polarity sensative, so I swapped the connection... Body of lamp + and wire ground..
Worked great..

Now, I looked closely at the fixture..

Note... the gold colored metal is connected to the single wire... so should be +... yet its the body of the bulb...
And the silver colored metal that has the the screw tab... that would be ground is connected to the center post of the bulb...

What is up with that?
I always thought the center pin is + and the body is grounded....

StreamRollin · 10-19-2012, 12:54 PM

Yours are different than my setup. When I replaced all my running lights and brake and backup lights with leds I used a wedge type bulb.So I did not have a issue with pos or neg .
Jim

Keyair · 10-19-2012, 03:13 PM

I was always under the impression that the center pin on bulbs like these was +... am I wrong?

Excella CM · 10-19-2012, 04:37 PM

It doesn't make a difference for tungsten bulbs-they're not sensitive to polarization. If you convert to led bulbs, you would need to change the fixtures or modify the ones you currently have.

Inland RV Center, In · 10-20-2012, 07:55 AM

LED lights are "light emitting diodes".

A diode is like a check valve, in that it allows something to flow in one direction, ONLY.

Therefore all LED lights "are indeed" polarity sensitive.

Andy

macofpei · 10-20-2012, 08:44 AM

You said "Swapping the stock 1157 incandecent bulb back in and all is normal again...
" there for, the problem is in the LED bulb. Check the contacts on the LED bulb. There is where you will find the problem, not in yout MH.