wiring question

I think you're right that a previous owner made this a shortcut wiring. I just rewired this part of my car and agree that it went through the firewall and then down alongside the inside of the tranny tunnel to the rear light switch. For what it's worth, at the time I ran that wire I thought it seemed odd that this wire was just sort of "hanging out there" so tucked it alongside the hard brake line. Maybe PO had the same thought and decided to make it a cleaner and less visible wiring by creating a more direct route through the tranny tunnel. The rear light switch has two male spade connectors on it for both of these wires.
 
I could the harness for the auto tranny selector with all its blue wires. Going to cut the tape off the interior harness and find out where it was spliced
 
As I recall there is a three pin connector on that wire. the harness side has a third wire (blue and white if I recall correctly) for the auto trans. For manual cars the other side of the connector just has two wires (that go down the trans tunnel).
 
I just put my reverse wiring in… mine went through the shifter… it’s where I had it labeled when I took it apart. Do not recall the wire colors.
 
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Wiring diagram shows #36 reverse switch wires Blue w/ White Stripe and Green w/ White Stripe and my 2800CS went with the window switches. I looked under ours yesterday but I had to add length so the colors aren't the same.
 
Let me look Scott. I may have when I took it apart. Dan is correct. It is with the window switches.

But it definitely went that way. When I rewrapped the wiring harness I did so as to leave the bends that developed over time. Made it easier to put it back in.
 
I just did a five speed swap on my 535is, and the reverse switch wiring runs through the boot around the tunnel and shifter to a connector just forward of the shift console. There is actually a small hole in the boot for the install. This is likely why you are seeing this routing as it appears BMW adopted this in lieu of the firewall/under dash wiring in the coupes.
 
if Dan, Todd + I all have this arrangement in the 2800cs, they must have changed it for the 3.0cs. Todd's is early 0111, mine is very late 0487 (built feb '71) ... and Dan's is 0394 (late '71 - perhaps built in fall 70)
 
so, the real question is why do i have wires coming through the firewall below the clutch master (green / white + blue / white) - see post 3 of this thread AND wires that went thru the tranny tunnel in post 17? puzzling ...

now for the next question - i've got to run my speedo cable ... i forgot where it goes through the firewall. is it right above the main harness?
 
Scott -- Perhaps I wasn't being clear in my earlier response. The original wiring for my coupe was under the dash and through the firewall as Chris and Steve has mentioned. My car is an early 72 auto. Blue/white and green/white and with stripes just like the ones in your post 3. When I did my five speed conversion on my coupe, I used this wiring.

My comment about the 535is was intended to communicate that by 1987, BMW was routing the backup light switch wiring up through the tunnel rubber boot that surrounds the shift lever to a connection just forward of the shift console near the light switches. This fits with the second set of wires you found in post 17. Moreover, these wires look like they were added to the car because the stripes surround the wires at 1" intervals as opposed to running the length of the wires. My guess is that whoever did your five speed conversion ran the wiring up through the tunnel near the shift lever and then spliced into the original wiring somewhere.

That said, I would locate the connections at the light itself and find out where you have continuity to wires you found. If the wires at post 17 are spliced into the original wiring, you should have continuity at both sets of wires and you can take your choice.
 
Chris, i understood your response and i think we have verified that the 3.0cs went thru the firewall. i was commenting on Dan Wood + Todd's post - both 2800cs going thru tranny tunnel. my dilemma is that i appear to have both ... and yes, i will have to test where i have continuity. have to get some other things done before i start sending power through the electrical system. too many things undone inside the car.
 
rsporsche said:
so, the real question is why do i have wires coming through the firewall below the clutch master (green / white + blue / white) - see post 3 of this thread AND wires that went thru the tranny tunnel in post 17? puzzling ...

now for the next question - i've got to run my speedo cable ... i forgot where it goes through the firewall. is it right above the main harness?
Click to expand...
I suspect the addition harness is because of an automatic.
My speedo cable is above the main harness.
 
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