Electrical Nightmare

[Repodog]

I took my recently acquired 1973 Overlander out for its first run of the year. My wife, 2-year-old and 8 month old couldn’t wait to be on the road. Alas, the trailer was not as excited. First problem; the 12 volt items in trailer would not work when tow vehicle hooked up and trailer battery not hooked up. Second problem, the trailer battery was dead and would not hold a charge. I replaced the battery and a large burned out 35v fuse. The 12-volt system worked fine, but still only off the trailer battery, not off tow vehicle. Third problem; I tried to drive. Trailer would not tow. The smell of burning brakes wafted through the air. As I sat stuck at the top of a hill, two blocks from home I went through the connections. (Wife and babies walked home a bit disappointed but quite pleased not to hear my “special language.” I unplugged the harness. Trailer brakes still engaged. Kill switch, I am not even sure that was hooked up properly to begin with. Disabled. Brakes remain engaged. Last resort, unplugged trailer battery – voila. Apparently, anytime I hook up my 12v-trailer battery, my trailer brakes engage (confirmed with compass). Forth Problem, we finally got to the RV Park. Once there, I decided to check the univolt as I remember many forum members discussing these issues. I couldn’t find it. What I did find was an after market charger. Per voltmeter, when I hooked up to 120, the charge to batter went down. Thus charger not working properly. If anyone out there can help suggest fixes to these problems I would greatly appreciate it.

Issues again are: Should the 12V system in trailer work if hooked up to tow vehicle and not trailer battery? What is the problem and fix re: trailer brakes engaged when I hook up trailer battery? Should I repair this after market charger – how, or replace it with a univolt or another after market charger? Please keep in mind I am a electrical novice. I know nothing about solving wiring problems. Finally, can anyone refer me to a person who can do a good job with trailer wiring problems in the Monterey Bay or San Jose area of Northern California? I would appreciate any and all help. Thank you.

[Safari Tim]

I would go with an after market charger like the intellipower with charge wizard. It seems to be the standard solution. It is a mulitstage charger which will keep you going without cooking your battery.

As far as the brakes go. Check the breakaway switch at the hitch area. That would apply power to the brakes with the trailer battery hooked up. Maybe your pin is out or yours is bad.

Also, your charge lead from your vehicle needs to be checked. Sometimes they need an extra fuse in the vehicle or perhaps yours is miswired in some way.

To give you an idea on the work involved in replacing the charger you can click the www button on my post and see how I did mine.

Good luck

[74Argosy24MH]

Should the 12V system in trailer work if hooked up to tow vehicle and not trailer battery?

If wired properly the trailer should not get power from the car battery when the ignition is off. If it did a couple hours of lights, water pump, and furnace would not leave enough power to start the tow vehicle.

John

[Chas]

Sorry to hear about your troubles but there is a saying, "A bad day camping is better than a good day at work"? Maybe or maybe not, huh??

I would do a bit of driveway camping until I got all the bugs worked out of your Overlander and take a small hour or two roadtrip and leave the wifey and the kids at home. Much better to deal with problems without the extra baggage, Did I say that??

Hopefully you didn't cook your brake magnets and I would definitely have a look at your umbilical wiring, sounds like you may have your battery feed and brake feeds swapped.

Chuck the Univolt and the glass fuse baloney, get the IntelliPower.

Chas

[overlander64]

Greetings Repodog!

I agree with Chas and suspect that you will find that there is a mis-match between the wiring in your trailer umbilical cord and your tow vehicle's wiring. This is a common problem with nearly all Vintage Airstream products as Airstream used a wiring scheme that does not match the current industry standard that your tow vehicle likely possesses. You can find the original Airstream wiring diagram for the umbilical cord on your trailer at:

Airstream 1966-1981 Umbilical Cord Wiring Diagram

When I hooked up to my '78 Minuet, nothing worked as intended. The backup lights were on continuously, and several other circuits were mis-matched. Knowing that this was a likely problem, I had a new Bargman trailer end in my toolkit that was wired and installed to match my Suburban. The current standard for wiring of the the Bargman plug can be found at:

Current Standard Bargman Plug Wiring Diagrams

Good luck in tracing down your electrical gremlins!

Kevin

[Repodog]

Thanks for the suggestions all. Anyone have an idea why my trailer brakes would be on when I hook up the trailer battery?

[overlander63]

Originally posted by Repodog
Thanks for the suggestions all. Anyone have an idea why my trailer brakes would be on when I hook up the trailer battery?

If you have a breakaway switch that is malfunctioning, it would engage the brakes when you hook up the battery. Check to see if the little cable seems to be pulled out. I am not sure if they can be unplugged for testing or not.
Another possibility is that the wire for the battery charge from the vehicle is touching the wire for the brake controls in the plug out on the tongue of the trailer.
Good luck with your gremlin.
Terry