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MG MGB Technical - orphaned brown wire??

Have been driving my 67 BGT after much frustration with the new carbs and ignition system meltdown. Drove after dark for the first time recently and discovered I had no low beams. Checked this AM and found I had parted the connector, an easy fix. BUT, also noticed a brown wire with a connector on it, the wire is hot, but can find nothing to which it needs to or did connect to and everything else seems to work. Is on the drivers side of a left hand drive car and is part of the original wiring harness. Any thoughts as to its purpose. thanks, Kenn
Kenneth von Wolf Lewis

Ken -
The brown is, as you mentioned, hot. It's used primarily to power accessories, most often the radio.

Brian
Brian S

Kenn. Is this within the passanger compartment or within the engine compartment? I know of no wires, brown or otherwise, within the engine compartment on the left hand side. There are some "always hot" circuits on that side, such as the brake light switch, but, on my cars, these are not brown wires.

The brown wire, constantly hot, circuits are seldom used to power such things as the radio--they would not be turned off when the ignition switch is turned off, but would be left on unless turned off manually. These items are, most generally, wired into the white wire circuit.

Get a copy of the wiring diagram, have it enlarged by a copy shop, and have them laminate it. Then, trace out the brown wire circuits, and the ones they feed. The Vis-A-Vis markers, being "dry erasable" are good for this process. This will help you determine what the wire might have originally been attached to.

Paul Hunt's "The Pages of Bee and Vee" has some excellent advice on trouble shooting electrical problems. When Paul does not have sufficient time to visit here, he does respond to e-mails through his website.

Get an enlarged copy of your wiring diagram. Trace out the circuits. And, is you still have problems, contact Paul.

Les
Les Bengtson

Ken,

At least until you figure it out, a loose brown wire in your engine bay (or anywhere else, for that matter) is an invitation to dissaster unless you have it well insulated - particularly at the end. If this is a correct original brown wire, it is hot ALL the time, unfused. Just make darn sure no bare part of it can get anywhere near a ground.

Allen
Allen Bachelder

The brown wire is just behind the dash, above the steering column. It has a connector on it, thus the wire is not exposed. My friendly mechanic, Eric Jones, has explained that it is a correct part of the harness, it is on the wiring diagram. Eric said it was used to connect to part of the indicator switch to allow for flashing the headlights. At the time this car was wired, very early 67, it was legal to do so in Great Britain, but not in the US. However, at his shop in Columbus,Ohio they often did wire up this connection for drivers. This is shown on the wiring diagramsin the factory shop manual as a dotted line. Thus endeth this mystery. Thanks to all, especially Eric.
Kenneth von Wolf Lewis

Les, actually, I do have a very large photocopy of the diagram on my garage wall and alternate lines are backcoloured in pale yellow to help trace them. Much easier on these old eyes. As I have no current plans to use this line I may disconnect the input end.
Kenneth von Wolf Lewis

I was just looking at the 1967 wiring diagram on page 190 of my Haynes manual and I see the wire you're talking about. Yes it shows dotted-line connections to the flashing headlight switch as well as one to a line fuse leading to the radio. Looks to me like it should be easy enough to disconnect from the unfused side of the fusebox. Just don't disconnect the wrong brown wire or you'll lose your horns.

FWIW,
Allen
Allen Bachelder

Kenneth.

I have a 67 GT. I know exactly the wire you are talking about. It drove me nuts for a number of evenings thinking I had done something wrong. I bet I went over the wiring diagram a dozen times.

This is a heavy brown wire. So it is a direct feed from the battery through the voltage regulator (if you are running a generator).

Could have been for the radio? Its position would be correct, but a heavy brown like that is normally used for high draw items, and as stated, it is continually hot even with the key off.

I have my headlight dip and high/low working and none use this connector. I just put a piece of tape over the connector.
Bruce Cunha

Bruce,

One of my minor projects for tomorrow is to very securely tape that connector over the wire.
Kenneth von Wolf Lewis

My original '66 came to me with the column headlight (passing) flasher and a radio that played with the ignition switch turned off. No need to power your ignition system (for hours) when parked with your favorite lady.
Steve Buchina

This thread was discussed between 15/09/2006 and 17/09/2006

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