hey guys, some of you may remember the post a few weeks ago regarding trying to hook up trailer lights. I started a new thread because some of my issues were fixed and wanted to skip past all of that. Long story short, I ran new wires from the side driver panel to the rear for markers, blinkers and brakes. I was getting 9 volts to the tail lights before, now I'm getting 11 volts (with engine off), so my lights are much brighter, and the trailer I have hooked to it is also MUCH MUCH brighter as far as markers go. But now I have a strange issue... here are a couple things that have happened...
-the blinkers on the trailer are so dim you can't really see them,
-when I turned on the right blinker, all the markers on the bus and trailer briefly would turn off and then back on, off and then back on... (circuit breaker maybe?)
-when the markers are turned off, and I hit the brakes, there is a delay before the brakes light up on the trailer... see this video... Trailer brake lights (http://www.youtube.com/watch?v=TjDWKoqDhow#)
I have wired trailer lights before so I'm pretty sure I wired it correctly, but there only thing I used that I've never used before is a 5 to 4 wire converter, since the bus has separate lights/wires for brakes and blinkers, and the trailer uses the same lights for brakes and blinkers. I don't know if this has anything to do with it, if so I would need to add lights to my trailer to separate the blinkers from the brakes. But this still doesn't explain the markers completely shutting off briefly.
One last thing I would like to add... when the engine is idling there is a gentle flicker in all of my lights if you watch real closely, in fact you can almost hear the engine going along with it, like the sound of the engine is barely changing as the lights change... barely. Thanks for your help guys!
Bryan make sure that you have a good ground for the trailer not just the trailer ball. If your bus is 12 volt you can buy a trailer tail light converter like used for Toyota/Nissan trucks that use separate lights for brake and turn signal lights to stop feedback between the lights. If bus is 24 volt then you use relays ,the number escapes me at this moment but maybe someone has the number.
Thanks! I think that is the converter that I'm using already. Tonight I bypassed the converter and it worked fine on either brakes or blinkers, of course I can't do both at the same time, so I've about decided in just going to buy another separate pair of lights on the trailer to use just as brakes.
Adding another pair of lights is the answer.
I have done that to all of my trailers and solved all the problems.
(Course it took me several converters $$$ to figure it out)
If you're not using a powered converter I would get one that is powered. You can also make your own with a few relays.
Curious, did you try any of this with the bus running and generating power? I suspect the 11 volts you are seeing at the converter is the problem.
Maybe try with the alternator running at 14 volts and see what happens.
There are plans on my website for a relay based converter. Many others available on the board, too.
Hi Bryan,
I have been using Gumpy's 24 to 12v relay set up for 5/6 years now and love it..
http://www.gumpydog.com/Bus/MC9_WIP/Electrical/Tail_Light_Converter/tail_light_converter.htm (http://www.gumpydog.com/Bus/MC9_WIP/Electrical/Tail_Light_Converter/tail_light_converter.htm)
Before his relays, I would install 24v bulbs in whatever I was towing and it was a real PITA.
At least I can tow anything now and not have to worry about voltages.
Good Luck
Nick-
you guys may need to school me just a little. Remember I'm a newbie still :D I was assuming that the bus was 12 volts simply because when I put a voltage reader to the battery it's approx 12 volts. What makes a 24 volt system? And how do I know what I have? Thanks!
Quote from: Bryan on March 10, 2014, 07:30:49 PM
you guys may need to school me just a little. Remember I'm a newbie still :D I was assuming that the bus was 12 volts simply because when I put a voltage reader to the battery it's approx 12 volts. What makes a 24 volt system? And how do I know what I have? Thanks!
Ooowa... That's a problem.. Lol
Bryan, if you have two 12v start batteries, that might be your sign..
I would start with your manual and then simply read the voltage on your starter. I'm pretty sure your
4107 is a 24v system. If so, could be why your having issues with trailer lights... You are probably
burning up the converter.
Nick-
Ok, wow! This could be a problem.
I'm not a GM guy, so I was assuming you knew how your own bus is configured, either 12v or 24v.
If a 4107 is 24v, then we need to back up and start over, because your 12v trailer (and converter) is NOT compatible.
According to Wikipedia... "The PD-4903 was the first GM bus to use a 24 volt electrical system."
My 4107 was before the 4903 correct?
The 4107 is 12 volts. It uses 2 12 volt batteries wired in parallel.
Bob
Good to know! Thanks Bob! I will proceed with adding an extra pair of lights to the trailer 😃
Did you try it with the bus running?
I had the same exact problems with my bus and it's definitely 24V. Turn signals were so weak you couldn't tell they were blinking and I know I had the correct converter in line. I eventually gave up and wired extra lights in the housing on the Liberty and now with the Mini I have bypassed the tail lights altogether and mounted LEDs in the bumper on either side of the backup light. They work great in any light conditions and I get comments all the time from Mini enthusiasts asking what the lights in the rear are for when we're not towing.
Will :D
okay here's the update. I ended up taking out the converter, and added an extra set of lights to the trailer. Now everything works great!!! I do have one question though. If you remember my original problem was low voltage therefore I ran new wire from side driver panel junction all the way to the rear tail lights. It increased my voltage by 2 volts and made the lights a lot brighter and also enough to light up the whole trailer. But here is something I'm still noticing. I'm not getting the same amount of voltage on the lights as I am from the battery. In other words, if I test on the battery terminals and I then I test on the lights, I'm still missing about a volt. Another thing I have noticed is if I test the hot side of the "marker" switch at the driver panel with lights off, I get full voltage, but as soon as I turn the switch on, it drops about a half of a volt on the hot side of the switch. I'm told by some truck driving mechanics that I should be getting the same voltage everywhere weather it's at the dash on in the tail lights themselves. Any ideas?
Now check the voltage at the battery when you turn the lights on. I bet you'll see a change there as well. You're adding a load on the battery without a charging system in operation.
Start the bus or put a charger on the battery if you want a stable reference voltage that doesn't react to load.
Brian - depending on the gauge of the wire you ran to the back you will get a voltage drop. This could be anywhere from .1 volt to a whole volt if the wire is thin enough. The thinner the wire the bigger the voltage drop. Here is a neat calculator for that - http://www.calculator.net/voltage-drop-calculator.html
-Sean
Fulltiming somewhere in the USA
1984 Eagle 10S
www.herdofturtles.org (http://www.herdofturtles.org)
new update... I did some tests while the bus was running. Like you said the voltage at the switch matches the battery when the marker lights are off. When running, the battery terminals and the switch both were at 14.1 volts. When I turn the marker lights on, it ALSO matches the battery but there is a drop. At the switch and at the battery it is 13.6 volts.
Just incase that didn't make sense...
Bus running at fast idle - Marker lights OFF - Switch = 14.1 volts
Bus running at fast idle - Marker lights OFF - Battery Terminals = 14.1 volts
Bus running at fast idle - Marker lights ON - Switch = 13.6 volts
Bus running at fast idle - Marker lights ON - Battery Terminals = 13.6 volts
I ran 12 gauge wire which I've been told was more than enough. And when I say I ran new wires, I simply ran them from the side driver panel junction box, all the way to the rear lights, I didn't rewire all the markers themselves and I also didn't rewire from the battery to the junction panel. But rewiring the parts I did increased the voltage to the tail lights by almost 2 volts.
What are you guys thoughts on this? Thanks!!! :D
Quote from: Bryan on March 22, 2014, 07:30:40 AM
I ran 12 gauge wire which I've been told was more than enough.
That depends what the current load is. How many lights you are powering with that 12ga wire?
12ga is good for about 18 amps.
There are only 4 lights running on the 12gauge wire (the tail lights)... All the markers are run like they were when we bought this bus. My marker switch also turns on the tail lights. 😃
In other words we didn't change anything about the marker wires. We just added a new wire for the tail lights in particular.