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Reverse light wiring

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Previously someone extended the two wires that come out of the tranny (blue and white, and purple and black) and ran a switch on the console. I’m looking to rewire this properly and am assuming that both of these wires go to the tranny switch. My question is about the other two wires in that loom. The black on and the brown and black. They are both cut. Are they just grounds and I can just fasten to the body on the floor pan? I know the black one is but not sure about the brow Black one.



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What year is your car?  Brown is ground, usually.  Black typically isn't so you may want to double-check that one.

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Its a 73 tii.  Looked over the wiring diagrams, you are correct that Brown is the ground. I'm assuming that I can just ground it to the body where someone has cut it. Where would the black wire run to?  Only wiring diagram I have is from a 71 and it does not show no side markers, only the roundie lights. Roman

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73 is still a roundie, right? Well here's where you find all of the good diagrams for starters:


And I'm looking at the US tii for 71-73 here:



I agree the Violet/Black wire should bring +12V to the reverse switch on the transmission, and then the Blue/White wire sends it back to the reverse lights.

I'm not convinced though, that the brown and black wires are for the side markers; according to the diagram they get their power from a green/red wire (along with the license plate lights) back by the tail lights themselves that comes straight from the light switch.

Your sure they're solid brown and solid black, right? If so, solid brown is ALWAYS ground, meaning it doesn't much matter what you do with that wire.  Either the other end is already grounded (so either grounding this end or leaving it loose both do nothing), or it is the ground wire for 'something,' in which case that 'something' will not work unless/until that wire gets grounded.

Solid black, well, here's the list of solid black wires I 'know' about on 2002s, though so far I don't any of them would be underneath by the transmission like that. . .

Rear defroster power

Tachometer signal from coil

One of the windshield wiper wires

A really fat one for the starter solenoid

MAYBE a wire for the heater blower motor (but I think that's only squaries)

MAYBE a wire for the tii time switch

MAYBE a wire for the seat belt switch contact.  Does your car yell at you to put your seatbelt on?  <- This is currently my best guess. . .


EDIT: On '74 squaries the rear side markers DO have black supply wires, but only very short pigtails in the trunk that come from the main green/white supply wire.  Also, in this case the reverse switch wires should be violet/white and blue/white, so I still don't think that black wire can be for the side markers.

Edited by AustrianVespaGuy
74 info

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Could those wires go to the sensors in the seat belts that cause the Fasten Seat Belt sign to illuminate until the belts are fastened?  That may be why they're cut.


I do know that the rear side markers are on a different circuit from the tail lights because on at leat 72 and 73 US cars, the parking and tail lights can be illuminated by selecting the left or right turn signal with the ignition off.  And that doesn't light the side markers.



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I have been trying to determine what wires are for the reverse lights and I have the blue binder 2002 factory manual. Despite combing through the wiring diagrams I have not yet found what wire feeds the switch with 12 v. The wiring diagrams do not agree with what I have at the trans in my 1973 2002. The wiring diagram in the later updates show that the blue wire with the white tracer feeds the backup lights from the switch.

I would have to agree with the Australian verspa guy that the violet with a black tracer feeds the switch with 12v. The manual however does not show that.

If this is incorrect please advise as I would like to wrap up the 5 speed conversion I did on this one.

I believe the other 2 wires , black and brown are for an automatic? as per some of the diagrams in the manual.

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