Taillight sensor affecting transmission shifting?

KGORDON19

MEMBER
2019 NISSAN SENTRA
4 CYL
2WD
AUTOMATIC
75,000 MILES

I have been having problems with my transmission slipping when shifting from a stop to 1st gear. I took it to the dealer and was told that the problem is rainwater getting into a broken taillight and causing the sensor to detect the brake pedal has been applied. I have my doubts and want to double check.

3 Replies

KEN L

MASTER CERTIFIED MECHANIC
43,047 POSTS

This car has the CVT transmission which they have had problems with. Can I ask if you hear any strange sounds coming from it? Also, do you have the check engine light on? If so, let's run the codes to see if any are stored.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

I don't see the brake light having a sensor for the bulb out warning but it does report to the BCM. I don't think that would affect the transmission, but you never know. I would service the transmission and filter while checking the condition of the old fluid (burnt). Here is how the job is done so you can see what needs to be done.

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Monday, February 19th, 2024 AT 9:58 AM

KGORDON19

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I'm not getting any strange noises, only the rumbling sound you get when the transmission is slipping. No check engine light either. My transmission is covered under warranty, but Nissan is telling me it's not my transmission, it's a faulty sensor. However, my car is not accidentally braking, it's slipping during acceleration. Nissan's explanation doesn't make sense to me, and it seems like they are trying to get me to pay for something else, so they won't have to fix my transmission for free. I've attached a copy of the service receipt so you can see what they say.

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Monday, February 19th, 2024 AT 10:06 AM

KEN L

MASTER CERTIFIED MECHANIC
43,047 POSTS

Yep, is the TCM is detecting the brake light being on it might cause a problem, but the noise will not. This sounds like the CVT belt has gone bad which is typical. Why can't we just fix the lens with a used one which wouldn't cost much to alleviate the problem, all you need to do it plug it in to see if the problem goes away, you can get one from Ebay. But my feelings are you are correct, they don't want to fix it for free. Sometimes and need it play the game to get them to fix it. Did you ask them why the transmission is making noise? Because this should never happen.

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Monday, February 19th, 2024 AT 10:38 AM