umbilical wire question?

[Mx468]

Does anyone know where this yellow wire connects to? I reconnected everything the way I thought everything was suppose to connect on my 72 safari airstream but I ended up with 1 loose wire? Its the yellow wire which comes from the umbilical cord from tow vehicle. See pic. I think its my reverse connect, but which wire do I connect it to from the trailer? Thanks.

[Farmer Dan]

I think you are right on the reverse light wire being yellow. On my 7-pin connectors it's on the center post.

Dan

[Boxite]

The yellow umbilical is for backup (reverse) lights. It's the center conductor/pin on your 7-way plug.

Unless your Airstream left the factory with BU lites.. it likely has no wire awaiting it's connection. It's likely capped off or connected to an unused terminal inside the trailer.
The taillight harness likely has a white (ground) wire and a black backup light wire.. the black one likely ends up not connected to the main wire harness at all (main harness will be missing the wire from the taillight harness to the umbilical.)

I had to run a wire from the taillight harness to the front of the trailer to connect the black backup wire in the taillight harness to the yellow umbilical connection up front.

[openroad118]

Which begs the question....why not add a light back there for backing in after dark? Has anyone done that?

[Lumatic]

In the 1972 service manual says the back up light is black.

A yellow wire from the tow vehicle according to the industry standard is left turn. Easy enough to figure that out.

The wiring in a 72 was before the industry standard. A yellow wire in a 72 was for trailer brakes.

Do you know if your 72 was rewired to match the current wiring industry standard?

Thoroughly confused yet?

[Lumatic]

Originally Posted by openroad118

Which begs the question....why not add a light back there for backing in after dark? Has anyone done that?

Are you talking about back up (reverse) lights? The old Airstreams had them. Or, are you talking about a flood light? Easy enough to do by replacing old bulbs with LEDs

[mimiandrews]

There's always the old fashioned way. Use an ohm meter to be sure the wire isn't connected to ground (the metal of the trailer) either intentionally or otherwise. If it is not, then power that wire from a battery or battery charger and see what comes on, or actuates if it's a brake. Wire color codes have changed over the years. Sometimes we have to let the electrons find it for us.

[Boxite]

Originally Posted by Lumatic

In the 1972 service manual says the back up light is black.

A yellow wire from the tow vehicle according to the industry standard is left turn. ...?

Confused yet? Yes.

The left turn "industry standard" is not yellow....EXCEPT on FOUR-wire systems. This OP is discussing a 7-Way umbilical where yellow is "reverse/backup" lighting.

The backup light wiring inside the trailer is black. (white is ground)

I added backup lights to my '08 model Sport: http://www.airforums.com/forums/f295...ts-159403.html