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Dave_H_M's avatar
Dave_H_M
Explorer II
Nov 03, 2013

12V Power From TV Prob?

This problem just cropped up on the most recent short trip.

For years when we stopped for an overnight dry camp, like wally world, I let the truck power cord hooked up and the truck running until it was bed time and shut things down so we started the night with a full batt if we needed some heat at night.

I usually go by the idiot xmas tree light on the fifth wheel panel. So last time out I pushed the switch to check and only three lights at max with the truck plugged in and engine on high idle (900rpm). Everything was great until the last trip.

I tokkk the batt to town and had it put on the tester. Techie said it was good.

So I probe around underneath front panel and look for the lead coming in that comes from the connector on the truck. I found a black wire that showed 14.2 volts when disconnected from the system. This corresponds to 14.2 volts showing up on the TV batt.

So if I take this wire that shows 14.2 V and apply it back to the system the voltage immediately reverts to battery voltage. it seems like voltage is there but no load can be provided.

What could this indicate? I thought maybe a poor connection either in the box on the RV or somewhere in the truck harness?

I got the voltage but no power (amperage), however it all worked great since 2010. Any thoughts?
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    Dave H M wrote:
    So if I take this wire that shows 14.2 V and apply it back to the system the voltage immediately reverts to battery voltage. it seems like voltage is there but no load can be provided


    Your tow vehicle is what 20 feet, say 30-40 feet of what, 12 ga wire between the batteries? plus assorted connectors and circuit breakers and such.

    What you saw is 100% normal. Give it five minutes and measure again, you SHOULD start to see an increase.

    or Alternative get a clamp on AC/DC multi meter from Sears and clamp it on that lead in first the 400, then the 40 amp mode, if the number is less than 10 amps (And it very likely wlll be) you can "Break" teh wire (Lift if off the battery) and put a cheaper multi-meter in the lead and confirm current flow into the battery.
  • Take a close look at the connector. I had to replace the connector to my toad this past spring.
  • SuperDutyFiver wrote:
    I agree-sounds so simple but def remove and cleanup all connections(from the plug on the truck to the battery cable clamps in the trailer) before you make yourself crazy!


    It depends on who you talk to as my state of mind on this issue. The plug and wiring in the truck is Bargman and is 2 years young. :h

    I am gonna give that ground issue some effort tomorrow. Thinking about cutting the connection of white wire s in the box on the trailer and doing it over for grins. Same for the black wire.

    And yes will take the ground for the camper completely out and reinstall.

    The onboard system via the converter works fine so it has to be delivery from the TV. :h
  • I agree-sounds so simple but def remove and cleanup all connections(from the plug on the truck to the battery cable clamps in the trailer) before you make yourself crazy!
  • Sounds like the charge wire, or the ground return, has developed a high resistance. I would check for corrosion.
  • There could be a fuse or circuit breaker between the battery and the DC power distribution panel. The circuit breaker could have a reset button. Look around where the trailer ambilical cord connects to the trailer wiring and the battery.

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