Trailer light wiring gremlins

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Alright so I have a 92 k1500 suburban with some wiring issues. When the truck is running with nothing plugged into the 7 pin connector something is drawing power from my battery. Also when I plug in a boat or something large, the truck goes instantly dead. The truck constantly runs at around 11 volts, I have a new battery, alternator, and 4/7 pin connector. The truck is equipped with a trailer brake controler, but it isn't hooked up to the 7 pin connector. Is the problem a crossed wire, bad ground, or something deeper? I am 17 and have limited electrical knowledge and can be clearer if need be.

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L29Sub

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Disconnect the trailer power red wire at the under hood fuse box.
Remove the blue wire from the back of the brake controller. Those are the only two leads that have power on them all the time.
Brake controller has a tickler that proves the brakes are connected.
Check your brake light switch for hanging on, and verify that the vanity lights inside the visors are not on (if they exist).
11volts is no charge. Dead battery. Alternator?

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Here's what I'm working with. The guy that we bought the truck from 2 years ago was an electrical engineer and may have reran the wiring. I can trace a blue wire from the rear trailer pin connector into the firewall. I also believe that the gray wrapped wires zipped tied to it may be associated with the trailer wiring(is behind the trans fill on the fuze panel picture.)
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95C1500

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Yeah, 11 volts running means the battery is not charging. I'd start there. If the alternator is new, check wiring and the voltage regulator.
 
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I haven't had time to do anything, but I had to jump the truck this morning, I don't know if the Wisconsin cold snap had anything to do with it, I haven't had to jump it since the new battery. It ran at 14 volts cruising at 65 all the way into town but the second I stopped it dropped.
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I dug around tonight and put a multimeter to the battery, it sat around 12 volts after charging shortly and when turned on ran at 11.4. After I turned the truck off it returned to 11.6. The alternator post, nut and wire were all at 1.5v(all with the trailer lights disconnected) I also followed the alternator wires into the harness and found a loose plug on the left side of the engine. What does it go to and is it related?
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L29Sub

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What are the wire colors?
And, does your alternator "fail" dash light operate? 12v typically won't start an engine.
Attach the meter set to 20vdc (or any dc scale greater than 12vdc). Ground the black or neg test lead and attach the red positive to the red 12 guage wire on the back of the alternator. Run at 2000 rpm and read. You should see 13.8 to 14.5 dc volts. If not, the alternator is failing. Or, the red charge lead isn't connected. If you read 13.6+ at the alternator, put the red meter lead on the battery positive terminal. It should read same as the alternator.
Shut the engine off and read the red alternator red 12 ga once again. Should read battery voltage. Identical to battery positive post. If zero at the alternator, resolve that. If it doesn't reach 13.6 v, when running the alternator has failed. Probably. There's plenty more...

Or, your voltmeter is failing.


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what the cluster is reading. When I unplug the battery charger I can watch the battery drain on the multimeter. The alternator always reads what the battery is reading but is always below 12V. I do have a spare junkyard alternator I can throw in tommorrow and see what happens. But the battery and alternator(rebuilt) are both a couple of months new from O'Riley's, I'm kinda mad if one has failed already. As for the plug the colors are orange and black.
 

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Disconnect the battery and charge it overnight. Remove the charger and it should read 12.6v or close. It should hold that voltage for several weeks. If it drops off over a day, or will not attain 12.6 v, it's bad.
You could check for a short by connecting doing a continuity read between the positive battery terminal cable (batter dosconnected) and see what it shows. You see a circuit and begin to eliminate the cause one fuse at a time. Pull the radio fuse first and leave it out. It has a memory. And remove theTekonsha brake controller plug. It also has a maintenance circuit. This process is tedious. But it will work.
The voltage you describe won't typically start and engine, unless jumping...? Alternators can charge at a low rate, and slower to be working. Also a failed alternator rectifier will result in a load when connected.




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Well the junkyard alternator is in and it jumped up past 14 volts. Gotta love it. Now to go back to O'Rileys and try to return the old/new one, it should be under warranty.
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