Posted 2009-06-14 1:54 AM (#106415) Subject: Goofy wiring questions
Member
Posts: 22
Location: SE Wisconsin
Hi all, hoping someone can give me an idea of what I'm dealing with here.Last year, I purchased my first trailer, a 95 CM 2 horse bumper pull and followed up that purchase with a 2002 GMC 2500HD :)The trailer has treated me very well, but it had some wiring issues from the very start, and I've now come to believe my truck may also be wired a bit "goofy".It took me quite a bit of futzing to get everything working correctly (well, correctly enough) and I really don't know much about this stuff but I'm willing to jump in and try. So I basically sat down with some paper and figured out which wire seemed to control what and by trial and error matched things up, I ended up replacing the 6 round plug on the trailer with one of those RV 7 plug ones so I wouldn't need an adapter between the truck and trailer.Since then, I've learned my life would have been easier if I'd known what a voltage meter was and had seen the "wiring" page on this website ;)Anyways, long story short, no matter what combo I tried, the best I could get was everything works on my trailer hooked up to my truck (turn signals, brake lights, brakes) but the running lights will NOT shut off when my truck is turned off. They stay on for quite a while.. they will eventually turn off (after an hour or more), so I usually unplug the trailer just so I don't have to worry about it draining my truck battery (it never has, but I don't want to risk it).That I can certainly deal with, though it would be nice if I could figure out why its doing it. Where it becomes a problem, and makes me think my TRUCK is wired goofy, is when I hitch up my mom's trailer to my truck, everything works except there are NO running lights at all. Exactly the opposite problem, and yes, we've made sure the headlights were physically turned on. (she has a newer keiferbuilt, and hauls it with a 2007 Chevy 2500). This is not a good thing, as I don't want to risk being out in bad weather or night driving with no running lights for sure if I have to haul her trailer for some reason. It has also been an issue when hauling a friend's horse in an emergency with her trailer (her truck died and I had to go pick them up).Also leaning towards my truck being wired goofy is the fact that it looks like someone backed the truck into something and the plug on the truck is slightly damaged and bent.. maybe someone just hooked it back up and switched some wires around.So anyways, I want to get it figured out one of these days, figure it should make a nice day, sit in the yard and putz project. Probably will just put a new RV 7 connector on the truck since this one is slightly damaged.First question, and forgive me but I've only used a voltometer once in the past.. what setting do I put it on to test these wires (amps or volts or whatever it is you set the dial to)?And secondly.. any ideas which wire it is that's probably giving me trouble on the truck side? Is it more likely to be the ground vs the aux or I don't even know what the 12v is used for. Obviously I need to take the truck plug apart and chart out my wire colors and see if they are out of place from standard or what's going on, and it will probably be self explainatory now that I know I'm looking for an issue more on the truck end.Third, can someone tell me quick about the ground vs aux vs the 12v? When should they be "hot" I guess is what I need to know, will all three of those be hot all the time? If they are all hot all the time, I guess other than going by wire color and hoping that it is correct, I don't know how I'll tell those apart on the truck end.For what its worth, the trailer breaks do engage when I use the slider on the controller, so I know that line is matching up, the turn signals match up, the brake lights come on when they should no matter which vehicle I hitch it to.. its just the running lights that act funny.I just don't understand why they are constantly on for one trailer, but constantly off for all others.. if the wire is hot, shouldn't it light up the running lights on both trailers even when the truck is off, or vice versa (no lights)? That's what's confusing me. My guess is that I will start with the truck, figure out which wire is controlling what with the voltometer, make sure they are wired in the standard "spots" on the socket (probably installing a new socket), and then I'm sure I'll have to tweak my trailer plug a bit to match up to it.. Thanks!*edit* whoa sorry, I did type this up with paragraph breaks...
Posted 2009-06-14 7:37 AM (#106421 - in reply to #106415) Subject: RE: Goofy wiring questions
Expert
Posts: 1416 Location: sc
The volt meter should be set to "VDC" or "Volts DC" or similar. I would start with the pickup and make sure it is standard. Keep in mind most wiring charts are viewing from the back as if you are wiring the plug, if you test from the socket side the locations will be "mirrored".
Start by grounding the volt meter to the frame then test the 12v, it should be hot all the time on your Chevy. If it is; then check the ground blade in the socket, should not have power. Next; 12v to ground in socket, should have power. The "aux" blade is used for the backup lights, it should only be hot when the truck is in reverse.
One of these testers can save a lot of time and aggravation.
Once you have the truck wired to standard, then get your battery charger or other 12v power source. You won't need the volt meter for testing the trailer. Ground the power source to the trailer frame, then apply power to each position in the plug. Take note which circuit is at each position in the plug, going by color is not reliable. You should also check the trailer ground by grounding the power source on the ground position in the plug and testing a circuit as described above. Once all circuits are identified, they can be set to standard and you'll be good to go.
My SWAG as to your problem; sounds as if the truck has had the aux pin altered to 12v hot on a timer. Most people have no need for back up lights on their trailers, and generally there are no circuits on the pickup that would shut off after an hour or so. If your trailer has been wired with the marker lights on the aux pin, then you would have no marker lights on the 2007..........except when the truck was in reverse, assuming it was wired standard.
Posted 2009-06-14 7:51 AM (#106423 - in reply to #106415) Subject: RE: Goofy wiring questions
Expert
Posts: 5870 Location: western PA
If your running lights are on all the time, you may have it powered from the hot wire from your truck, instead of your lighting circuit. Set your multimeter on 12V DC. Clip the black wire from your meter to a good bare spot on your truck's frame or bumper. This will be your ground. Then by touching the various terminals inside your plug with the red wire, you can determine which ones are hot when the meter reads 12V.
Your lighting circuit for the running lights. should only show a 12V voltage when your headlight switch is "on". When it is turned "off", you should not show any voltage.
Some trucks have a constantly powered aux circuit for interior lighting and battery charging. Some have a timer that disconnects the power after a time limit to prevent the battery from becoming discharged. Your running lights may be connected to this circuit.
Retento has, in the past, posted some wiring diagrams for various trailers and truck plugs. Perhaps he could do it again.
Posted 2009-06-14 8:05 PM (#106438 - in reply to #106415) Subject: RE: Goofy wiring questions
Member
Posts: 22
Location: SE Wisconsin
Thank you much guys. I have the trailer wires figured out by color just from messing with it last year (I wrote them all down), so I"m pretty sure its just the truck I'm going to have to figure out.The info you've given will help me a ton, especially if the wires are not correctly color coded (I'm assuming they will be, but you just never know).Also, thanks for the mention of the diagram being backwards from the wiring side and not as if you were looking at the socket.. that would have thrown me for sure.
Goofy wiring questions
