Trillium brake light problem -- help! - Fiberglass RV


Reply
 
Thread Tools Search this Thread Display Modes
 
Old 06-10-2008, 10:04 PM   #1
Junior Member
 
Trailer: Trillium 13 ft
Posts: 7
Hi all:

Of course, these things always happen just as you're ready to leave on a big trip!

Here's what's happening. The right brake light on my Trillium isn't coming on. (The left is functioning normally). The Trills use a single, dual-filament bulb. One filament is on all the time (as a running light) the other handles the brake/turn signal function. On the right bulb, the running light filament is lit fine, but the brake one doesn't come on. I tried a new bulb (and swapping with the left side), but no dice -- same results.

And now here's the thing... When I take the bulb out and measure the voltage in the socket, I get a little better than 9 volts at each of the two pins -- so there's voltage getting to both filaments, but only one is lighting. (That 9V might seem a little low, but that's about what I'm getting at the left socket too, which works fine.)

Any electrical geniuses out there want to offer a thought? Any help appreciated.

Thanks,
Gary
__________________

__________________
Gary Seronik is offline   Reply With Quote
Old 06-10-2008, 10:20 PM   #2
Senior Member
 
Doug Mager's Avatar
 
Trailer: 1975 13 ft Trillium
Posts: 2,536
Registry
almost always the culprit IS a bad ground connection!!!
__________________

__________________
Doug Mager is offline   Reply With Quote
Old 06-10-2008, 11:06 PM   #3
Senior Member
 
Alf S.'s Avatar
 
Name: Alfred
Trailer: 2014 Escape 5.0TA / 2010 Nissan Frontier
Ontario
Posts: 3,815
Registry
Send a message via Yahoo to Alf S.
Hi:Gary... Also check the tug plug and the trailer connections. Flat 4/ 6& 7 pin. I had a bleed thru problem where a single strand of wire escaped from under the set screw allowing current to pass over that connection. It is usually a simple thing... just difficult to find!!!
Alf S. North shore of Lake Erie
__________________
Alf S. is offline   Reply With Quote
Old 06-11-2008, 05:13 PM   #4
Junior Member
 
Trailer: Trillium 13 ft
Posts: 7
Proving that the obvious and common reason might not always be the correct one...

I found the source of my problem. I was thrown off the scent by the fact that I was getting voltage in the socket, yet the lamp refused to light. I figured that something had to be changing when the circuit was being loaded. I bought a new socket, but that didn't cure the problem, so I started to use logic instead of guess work.

In the Trillium, power travels from the 7-pin socket into the trailer via the main power cord. Inside the trailer, the cord feeds two circuit blocks where the various wires that run inside the trailer meet the main cord. It turns out that the nut that locks down the wires on one of the terminal blocks had vibrated loose. This, of course, turned out to lock down the wire that fed the right hand brake light. Once tightened down, everything worked normally.

The nut was loose, but the brake wire was still making contact well enough that I could read voltage at the socket, but the minute the circuit was loaded differently (when the bulb was put in the socket), the circuit became an open. Hope that makes sense.

Anyway, thanks to those who offered suggestions -- it's reassuring to know that there are group members willing to jump in!

Gary
__________________
Gary Seronik is offline   Reply With Quote
Old 06-11-2008, 05:39 PM   #5
Senior Member
 
Pete Dumbleton's Avatar
 
Trailer: Scamp
Posts: 3,072
Send a message via Yahoo to Pete Dumbleton
What you found is a common problem with 120VAC switches, esp vacuum cleaners. The continuity across the switch looks good with a meter, but it just won't work. About the only way to find it is to bypass the switch.
__________________
Pete Dumbleton is offline   Reply With Quote
Old 06-11-2008, 06:16 PM   #6
Senior Member
 
Byron Kinnaman's Avatar
 
Name: Byron
Trailer: 2006 Scamp 13' towed with a 2005 Dodge Dakota 4.7l Magnum W/full tow package (over kill)
Oregon
Posts: 6,307
Registry
What happens is that there is a connection but no enough of a connection to carry the current required to light the bulb. When you attempt to turn on the bulb that connection heats up and opens.

Doug, it wasn't a bad "ground".

I doubt that most trailer electrical problems are associated with the ever elusive "ground", or the real negative battery connection.
__________________
Byron & Anne enjoying the everyday Saturday thing.
Byron Kinnaman is offline   Reply With Quote
Old 06-11-2008, 07:04 PM   #7
Junior Member
 
Trailer: Trillium 13 ft
Posts: 7
Quote:
What happens is that there is a connection but no enough of a connection to carry the current required to light the bulb. When you attempt to turn on the bulb that connection heats up and opens.
Perhaps, but in that case, I'd expect to see the light come on for a moment at least -- until the connection heated up and failed. What I think happened is simpler. See if this works for you...

Imagine that the circuit consists of two resistors in series. One resistor is the faulty connection whose value is unknown. In case #1, the second resistor is the meter. Digital meters tend to have huge resistances (in the mega ohm range). So, we have a series circuit with one small resistance (the faulty connection) and one big resistance (the meter). Ohm's law says that most of the voltage will be dropped across the big resistance of the meter, so the meter reads what appears to be the nominal voltage. Okay, in case #2, we take the meter out and replace it with the bulb. We're still dealing with two resistors in series, but it's the faulty connection (unknown resistance) and the bulb, which has a resistance that's very low -- essentially zero. Again, Ohm's law says that most of the resistance is dropped across the biggest resistor, which in this case, is the faulty connection, not the bulb.

Make sense?

Gary
__________________
Gary Seronik is offline   Reply With Quote
Old 06-11-2008, 07:43 PM   #8
Moderator
 
Frederick L. Simson's Avatar
 
Name: Frederick
Trailer: Fiber Stream
California
Posts: 8,151
Registry
Send a message via AIM to Frederick L. Simson
Unhappy

Quote:
Of course, these things always happen just as you're ready to leave on a big trip!

Here's what's happening. [b]The right brake light on my Trillium isn't coming on. (The left is functioning normally). The Trills use a single, dual-filament bulb. One filament is on all the time (as a running light) the other handles the brake/turn signal function. On the right bulb, the running light filament is lit fine, but the brake one doesn't come on.
I just experienced this same symptom! I was hitching up to leave for my Birthday weekend get-away.

I discovered that the problem was that my 7-pin trailer plug didn't seat properly when I plugged it into the socket on the back of my van. The Right Brake/Turn Signal was the only circuit affected.
__________________
Frederick - The Scaleman
1978 Fiber Stream 16 named "Eggstasy" & 1971 Compact Jr. named "Boomerang"
Frederick L. Simson is offline   Reply With Quote
Old 06-12-2008, 10:13 AM   #9
Senior Member
 
Byron Kinnaman's Avatar
 
Name: Byron
Trailer: 2006 Scamp 13' towed with a 2005 Dodge Dakota 4.7l Magnum W/full tow package (over kill)
Oregon
Posts: 6,307
Registry
Quote:
Perhaps, but in that case, I'd expect to see the light come on for a moment at least -- until the connection heated up and failed. What I think happened is simpler. See if this works for you...

Imagine that the circuit consists of two resistors in series. One resistor is the faulty connection whose value is unknown. In case #1, the second resistor is the meter. Digital meters tend to have huge resistances (in the mega ohm range). So, we have a series circuit with one small resistance (the faulty connection) and one big resistance (the meter). Ohm's law says that most of the voltage will be dropped across the big resistance of the meter, so the meter reads what appears to be the nominal voltage. Okay, in case #2, we take the meter out and replace it with the bulb. We're still dealing with two resistors in series, but it's the faulty connection (unknown resistance) and the bulb, which has a resistance that's very low -- essentially zero. Again, Ohm's law says that most of the resistance is dropped across the biggest resistor, which in this case, is the faulty connection, not the bulb.

Make sense?

Gary

That's a possibility. Here's a more technical explanation.
More likely the point of connection was very small thus creating the high resistance at higher current levels. Conductor resistance is inversely related to the crossectional area of the conductor. Then to complicate it even more, the apparent resistance is related to the amount of current attempted to push through that small area. Meaning that the more current you attempt to push through that small area the greater the apparent resistance. (This why you need larger wires for larger currents) Volt meters are designed to have minimal effect on the circuit they're connected to which translates to high input resistance, generally 100 megohm minimum. That translates to very small current, which would pass through a very small conductor easily.

When you connect the lamp bulb, which has a cold resistance near 0 ohms the small crossectional area conductor will heat up very rapidly and open. Incandescent lamps take time to heat up and produce light, the small crossectional area will open long before the filament is hot enough to see.

Looking at the connection point under a microscope you'll see burn spots where the burning open happens, probably several.

That's probably more than you even wanted to know.

Byron

__________________
Byron & Anne enjoying the everyday Saturday thing.
Byron Kinnaman is offline   Reply With Quote
Old 06-12-2008, 11:42 AM   #10
Junior Member
 
Trailer: Trillium 13 ft
Posts: 7
Quote:
That's a possibility. Here's a more technical explanation.
More likely the point of connection was very small thus creating the high resistance at higher current levels. Conductor resistance is inversely related to the crossectional area of the conductor. Then to complicate it even more, the apparent resistance is related to the amount of current attempted to push through that small area. Meaning that the more current you attempt to push through that small area the greater the apparent resistance. (This why you need larger wires for larger currents) Volt meters are designed to have minimal effect on the circuit they're connected to which translates to high input resistance, generally 100 megohm minimum. That translates to very small current, which would pass through a very small conductor easily.

When you connect the lamp bulb, which has a cold resistance near 0 ohms the small crossectional area conductor will heat up very rapidly and open. Incandescent lamps take time to heat up and produce light, the small crossectional area will open long before the filament is hot enough to see.

Looking at the connection point under a microscope you'll see burn spots where the burning open happens, probably several.

That's probably more than you even wanted to know.

Byron
Excellent explanation Byron -- exactly what I wanted to know.

Thanks,
Gary
__________________
Gary Seronik is offline   Reply With Quote
Old 06-12-2008, 07:44 PM   #11
Senior Member
 
Pete Dumbleton's Avatar
 
Trailer: Scamp
Posts: 3,072
Send a message via Yahoo to Pete Dumbleton
Byron, I just fixed a neighbors utility trailer's lights and indeed it was a grounding problem caused by using the trailer chassis as a negative battery return. I ran a negative wire around to each light fitting and tied it also to the frame at each fixture.

Most of the trailer light problems I've worked on have been caused by bad connections to the chassis ground for the negative battery return. Second most common for me has been damaged wires (Flat-4) on the connector end. Third has been a mixture of corrosion at fitting or bad bulb.
__________________
Pete Dumbleton is offline   Reply With Quote
Old 06-12-2008, 09:45 PM   #12
Senior Member
 
Byron Kinnaman's Avatar
 
Name: Byron
Trailer: 2006 Scamp 13' towed with a 2005 Dodge Dakota 4.7l Magnum W/full tow package (over kill)
Oregon
Posts: 6,307
Registry
Quote:
Byron, I just fixed a neighbors utility trailer's lights and indeed it was a grounding problem caused by using the trailer chassis as a negative battery return. I ran a negative wire around to each light fitting and tied it also to the frame at each fixture.

Most of the trailer light problems I've worked on have been caused by bad connections to the chassis ground for the negative battery return. Second most common for me has been damaged wires (Flat-4) on the connector end. Third has been a mixture of corrosion at fitting or bad bulb.
The operating words are "Most trailers, chassis (chassis = frame) used as negative power", hence the confusion. Most fiberglass travel trailers don't use the frame to conduct electricity, negative or positive.

The connection to the frame with most trailers is caused by corrosion from the use of dissimilar materials accelerated by moisture and road chemicals along with electric current going through the connection. It all adds to the failure issue.

Since our trailers don't use the frame for current flow there's fewer dissimilar material connections and connections are inside it's less likely that a connection failure would favor one side of the power system vs the other side.

Furthermore in the OP's first post he stated that the "running light" section worked, meaning the tail light. With a 2 filament bulb, 3 connections and two are working, seems to leave just one connection that failed somewhere in the system. The problem couldn't be the negative side since it was already shown to be working. That should have been obvious from the beginning.

Furthermore number 2. There's only one ground in my fiberglass trailer, it's a green wire that connects to the shore power cord, the duplex outlets and to the frame. There isn't supposed to be any current flowing in the ground connection. It's there for safety purposes only.

OK by $.02 worth.

Byron
__________________

__________________
Byron & Anne enjoying the everyday Saturday thing.
Byron Kinnaman is offline   Reply With Quote
Reply

Tags
lighting, lights, tail lights, trillium


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
3rd Brake Light Help D Tharp Problem Solving | Owners Helping Owners 16 04-16-2010 07:48 PM
3rd Brake light Kevin K Modifications, Alterations and Updates 10 10-04-2008 07:09 AM
Brake Controller Light Legacy Posts Problem Solving | Owners Helping Owners 10 04-20-2003 08:08 AM
brake problem Legacy Posts Towing, Hitching, Axles and Running Gear 2 10-20-2002 05:34 PM
Trillium brake light problem -- help! Gary Seronik Problem Solving | Owners Helping Owners 0 12-31-1969 07:00 PM

» Upcoming Events
No events scheduled in
the next 465 days.
» Virginia Campgrounds

Reviews provided by


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 04:47 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.