Extra Wire (mystery)

[bubby-joe]

I have a blue wire (probable an add on) coming from a screw in switch on the rear of the engine block just above the oil pan and below the rear engine mount spacer, facing the rear tire, the wire is going up the left side frame rail and under the fuel tank then hanging in the air at the steering head there is no other loose or unconnected wires on the bike and everything works just fine without this wire, the Haynes manual does not show this switch hole on the engine block pictures or the wiring diagrams any ideas as to what it's for or where it's supposed to go. Bikes a 1980 R-65 US model

[Rob Valdez 79 R65]

I don't know why it is blue, unless it has bee replaced.
The location you describe sounds like the neutral switch on the bottom of the transmission.

Can you start the bike without pulling in the clutch?

[montmil]

Does your '80 model have the neutral indicator switch with two wire attach spades or is this switch some type of PO add-on? Doubtful, that...

The neutral switch wiring passes through the starter relay. Unless the original two switch wires are joined to bypass the switch, you'll have starting issues. But you say everything works.

Any chance you might be able to post a photo for clarification?

Monte

[bubby-joe]

The neutral light works, properly.  The wiring diagram does not show a clutch lock out.  If I start in gear I have to pull the clutch in if that's what you mean that works as it should.  It's a single wire switch/sensor coming out the rear of the engine block not the transmission, between the transmission and the oil pan on the rear of the engine block below the rear motor mount spacer and oil pan gasket surface.  All the dash lights, oil light, neutral light, park light, headlight, brake, signal and tail lights work without this wire being hooked to anything.  The wire passes through under the tank past the relays and regulator to the steering head area and just hangs in the air with nothing to connect it to in that area.  I'll see if I can get in there to take pictures later this afternoon.  Like I said a mystery wire.

[Semper Gumby]

The only Solid Light Blue wire in the BMW system is the D+ wire from the Alternator to the Voltage regulator?   :-?

Time to look at the diagram again.

[Rob Valdez 79 R65]

It could be a PO added a oil temperature gauge?

Pictures.

[bubby-joe]

It could be a PO added a oil temperature gauge?

Pictures.

That is a possibility  3 pictures included got sidetracked yesterday.

I know the wires not in the wiring diagram there is no single wire switch or sensors on the bike, in the diagrams, hence the use of the term MYSTERY wire.

Oh yah no longer pumpkin but a tremclad metal flake clear coat to follow for this year it's a dirty rider next year it gets paint and body work everywhere.

[Bob_Roller]

I'd go out on a proverbial balsa wood limb, and say you have an oil temp sensor on the oil pan .

It's not an OEM installation, it's a previous owner add-on .

[bubby-joe]

I'd go out on a proverbial balsa wood limb, and say you have an oil temp sensor on the oil pan .

It's not an OEM installation, it's a previous owner add-on .

COPY that no more mystery out it comes  (snip gone less than 30 seconds)
It was very poorly done anyway.  Junk wiring is the bane of most motorcycles look to Lucas prince of darkness.
I'll donate the wire to a Subaru to VW Vanagon  swap.

[montmil]

My 1981 R65 came with the remnants of a fairing wiring harness complete with some very uncool wire nuts and those horrible rabbit's teeth wire connectors that cut through the sheathing. Sad work.
I, too, saved the wire... pretty colors!

Monte