low voltage?

[DON]

On my 76 winnabago chieftain, at the trailer hook up at receiver I have only around 8 volts output.  The lights are also dim.  Any thoughts as to what I might check?  Should not the output be like 12 volts on the voltmeter?  Even with engine running, still get around 8 volts.  Thanks.

[beaverman]

which lights are dim? headlights? tail lights? all ?

[DON]

The taillights seem to be dim.  Removed lenses and wiped clean.  Old and worn.  Checked voltage at trailer plug.  Around 8 volts.  Brother thought it should be 12.  Did not check voltage at taillight.  Rv not in town.  Go when I can.  Realize brightness not great because of age of rv, but want the taillights and brake lights to be seen for safety.  Headlights are not super bright, but not bad.  Maybe age of rv.

[Rickf1985]

Trace the wiring harness back and I will bet you find an area where trailer wires have been spliced in. In that area the wires will be corroded and the resistance will be high causing your low voltage. The only repair if this is the problem is to cut out the entire bad section and replace with new but use marine heat seal connectors when you do. Use those connectors for any wiring work. If that is not the problem track down any ground wires in the rear harness and clean the grounds.

[DON]

Thanks.  Always learning something here.

[Rickf1985]

Bad grounds are 80% of all of the electrical problems. They may look like something else but it usually boils down to a bad ground. I mentioned the connection area because of where you are checking and many years of past experience dealing with corroded wiring from pierced wires for trailer wiring. Always try to avoid piercing a wires insulation, even the smallest pin hole will allow moisture into the wire and it will turn green for several feet in both directions. That can ruin a circuit. Whenever you need to join wires under a vehicle, I even do this inside, use marine heat seal connectors. They use heat and shrink down on the wire and also use glue to completely seal the connection.

[DON]

Good to know.  Thanks.