cvt slips but also brake lights inoperable?

[Dosmastr]

Hi all,

Just last fall replaced the OCS so the passenger had protection.
And now the transmission was slipping from take off...

Pulled the codes but something is weird.
One is faulty tcm but the other is brake lights??

These things aren't even near each other, how could they fail at the same time?
I followed this car home in mine on Sunday and the brake lights worked fine.

What's the common point that I should be checking on this?

[Dosmastr]

Cvt Fluid level and condition appeared fine

Hard to see the brake lights but I put my phone on the wiper and pointed at the center brake light. No illumination.

[VStar650CL]

The P1701 is the TCM power supply, so check the TCM fuse in the IPDM. That code will often pop up from a low battery condition and may be old, so if the fuse is good, just see if the code will erase. If it won't, then you may have a wiring issue or a problem in the Valve Body or TCM.

The P0703 may be from a bad brake switch, but can also be caused by crosstalk between the taillamp circuits, usually because of moisture in one of the lamps. The CVT will absolutely refuse to allow acceleration if it thinks the lamps are lit, and it only takes about 1.5V of crosstalk to make it think they're on. That can also be caused by crossed bulb filaments in a blown bulb.

[Dosmastr]

Oh my God thank you SO MUCH.
I KNEW there had to be some kind of connection!

So the "slipping" at takeoff is likely the engine is responding as commanded but the transmission is seeing the brakes applied and not engaging? That makes sense, all the slipping videos I found were at highway speed, AFAIK this was only from stops

It was quite cold but the 12v battery isn't that old. Car starts up just fine.

Am i interpreting the code reader right the confirmed codes are current?
The low tire pressure showed historical but NOT confirmed.

Checking brake bulbs!
Got c1116 brake lights too

[Dosmastr]

Brake lights both light when car is locked/unlocked.

[VStar650CL]

Yah, the C1116 pretty much clinches it. The switch has two different throws and when they get out-of-sync, all sorts of weird stuff can happen. So if you don't find any problems in the bulbs or fixtures, try a new brake switch.

[Dosmastr]

This switch has continuity on both the top 2 pins and also the bottom two pins when not pressed.

And has no continuity at all when pressed....
All the videos say one set should be inverted from other (one always closed one always open)

Is nissan different?

Got the switch apart and it looks like there's there's a ballpoint pen spring that's supposed to sorta act like a spacer, allowing one set of contacts to close while forcing others open... but deeper in is a FAR stronger spring that requires the small spring to bottom out and then have the white shift force open the inner contacts.
However, the bottom being pressed in all the way breaks the outer contacts too.

Looks like only in certain point in the travel is one contact open while other closed.

[VStar650CL]

Some Nissan switches are NO/NC, others are NO/NO, sounds like yours is the latter. Regardless of which, ideally there shouldn't be any difference in activation point between the two throws, they should operate simultaneously. Most of the time when they go bad, it's because the "lamp throw", which carries much more current than the "signal throw", gets a bad spot in the plating and starts to make contact late or not at all. Then it becomes a case of, "The man with one watch knows what time it is, the man with two is never sure."

[Dosmastr]

It's just the part that clicks, that little travel between end of motion and click.
Curious why it would be 1 switch which internally is 2 if they are to just read the same

[VStar650CL]

I suppose it's intended to be a failsafe, but in practice it mostly turns into a fail-guaranteed because the car's firmware mishandles it instead of treating it as a coping mechanism. I don't ask why my dog wants to lick my face for 20 minutes a day, it's just how he's made. Asking a Nissan engineer those sorts of questions generally gets me similar (non-)answers.

[VStar650CL]

Ya know, I actually need to vent about this.

Why do Nissan "Distance-to-Empties" all demand that you turn off the car (even at the North Pole) and put in at least 4 gallons, or they won't reset properly?
Why do gen2 Versas have, of all things, powder-coated ground terminal brackets.
When used in Manual Mode, why do Nissan Auto A/C's not respond proportionally to the temp dial like a Manual A/C?
Why are Nissan "smart" alternators not smart enough to correlate the battery current sensor with the alternator output and state-of-charge, and instead let the battery die from under-charge if the current sensor is lying?
Why, in general, are DTC's like the OP's used as excuses to disable the car and preserve the machine, instead of doing their best with what they have in order to preserve the occupants.

That's a small sample. Inquiring minds would like to know, but all I get from Nissan and Bud-Bud is, "Arf."

[Dosmastr]

This is promising.

[Dosmastr]

Still showing both codes, and the odb2 max app is really scary "might break something, DEV NOT LIABLE!!"

So...because I'm letting it spook me I'm going to pull the neg lead...

[Dosmastr]

Well had to use the obd2 to clear anyway, battery disconnect cleared everything but the codes...

[VStar650CL]

The P0703 is specifically for the lamp throw turning on but failing to turn off, and it's usually from too much slop in between the paired throws. It only takes about 1/20 of a second of early or late operation to trip a code. Replace the switch, then start hunting for other stuff if the new switch doesn't clear it up. I should have mentioned at the top, ever since Nissan went to plastic switches in the early 2000's, they're absolutely infamous for causing this sort of crap. So you're not alone here, it's very, very common.

[Dosmastr]

My last reply yesterday didn't post!
I took apart the switch and cleaned it, then reassembled and reinstalled (brake light photo is post reconnection but before installation. )
Cleared the codes and so far so good
The grommets looked to be in pretty good shape. I wonder if it just needed to be bumped on notch on the install bracket.

You saved me potentially hundreds of dollars.

[VStar650CL]

Happy to help. I'd suggest getting a reputable replacement switch from RockAuto to have on hand. You can get a decent Beck-Arnley for $19. Usually the problems arise from the same sort of microscopic plating erosion that befalls Altima shifters, so in the long run it will almost certainly repeat itself. It isn't like installing a new one is rocket science, so keeping a new spare in the glove box will likely save you some grief down the road.

Happy motoring!