transmission just started eratic shifting

[tylojack]

help, my 2003 G35 just started shifting eratically. it shifts out of low, then back into low. also, the automatic/manual option wont work. when i shift over from drive to 4, it stays in drive, also, if i start out in manual 1, it jumps to drive from 2, it wont let me do it manually. it worked fine a couple of days ago. i should mention, this is a coupe, with 58,000. i checked fluid level. its perfect, and clean and pink. help

[Haitian_King]

Do you have the G35 FSM? It might help. Hopefully there something in there about it. If it's anything like a Q45, there'll be a transmission self-diagnostic that you can run. It'll bring up a code, and you can check the code in the code list in the FSM.

http://www.nicoclub.com/FSM/G35/Coupe/2003/at.pdf

[tylojack]

no, i dont have a fsm(factory service manual?) im taking it to the dealer tommorrow and i was concerned about what was wrong with transmission and window(mentioned before) the window doesnt worry me as much as the transmission, i mean it just started all of a sudden, i havent had the car but for a few days, and everything was fine before (except window) im starting to have second thoughts, and i was wondering if this was common?(the problem). The trans seems like an electrical thing, instead of mechanical. i just dont understand what happened? do you think its a major deal, and even if its fixed by dealer, is it probally gonna occur again? i've always owned toyotas and hondas, and never had problems, but this is my first infinity. anyway, thanks for the post, and if you have anymore advice/answers, please send them my way!

[Haitian_King]

I'm going to assume it's a solenoid. But don't hold me to it. Read the AT section of the FSM. Especially where it lists symptoms and possible diagnostics. You might find something out from there and not have to pay the dealer to tell you something you already know.

Even if you do decide to go to the dealer, don't be left helpless. It's good to be able to figure things out on your car. Makes you appreciate it more.

[Q45tech]

The newer 5 speed AT seem pretty reliable especially when used with V6 since they were designed to handle V8 torque.

There was an early [2004] redesign where the TCU was integrated into transmission housing.

A pan drop looking for metal slivers on magnet and a filter and fluid change is often helpful.

The dealers are really the only ones experienced so far since the design is so new [5 years]. We only have about 50 customers with this new transmission, so far so good.

[tylojack]

i had checked the fluid level and color. it was correct with pink, non burnt smelling fluid. i took it to dealer, and as i thought, diagnostic check shows a sensor(1 of 4) and they are in the process of narrowing it down. mechanical wise im sure its fine, although im new to infinity's, so i was wondering about realibility. what concerned me most, was the fact, the manual mode would not work at all. if you shifted from drive to manual, it remained in drive. at a complete stop, if you put it in manual, it would start off in first, but wouldnt let you manually shift to 2nd, 3rd, etc it would jump back to drive mode. i was wondering if this was common? it only has 58,000 miles, but i do plan on a filter and fluid change. thanks for your reply/help!!!

[tylojack]

exactly, i like to have an idea of whats going on, even if i cant fix it and have to take it to dealer. when you can explain whats going on, and have a general idea of whats happening, the dealer, or service reps arent as likely to pull one over on you! thanks again for help/advice

[Haitian_King]

Yeah. That sounded like an electrical problem rather than a mechanical one. But I'm not familiar with G35 transmissions. Did you go through the symptoms/diagnostics in the FSM?

My bet is your vehicle speed sensor. Page 41 of the FSM says that if there's a malfunction in the VSS, 5th gear and manual are prohibited. Probably why you can't use the manual function. Since you're stuck in 2nd, I suspect it's your A/T's fail-safe.

G35's are interesting. If one part of the trans fails, normal driving can still be done.

Read this section. Seriously. I'm just tossing these things because they match up with what you've been saying. I don't know for sure.
Modified by Haitian_King at 4:27 PM 11/19/2007

[tylojack]

NO, ITS NOT ACTUALLY STUCK IN 2ND, IT JUST SHIFTS WEIRD, ESPECIALLY IF YOU TRY IT IN MANUAL, WHICH WILL ONLY, KINDA WORK, IF YOUR SITTING STILL. WILL NOT GO IN MANUAL AT ALL IF YOUR MOVING. I CANT SEEM TO GET THE FSM TO LOAD COMPLETELY. I'VE TRIED SEVERAL TIMES, AND IT GETS TO DIFFERENT PARTS, BEFORE I GET A DOWNLOAD ERROR. FIRST MY CAR, NOW MY COMPUTER!!! ANYWAY, I'LL KEEP TRYING!! I GUESS WILL ALL THOSE PAGES, IT TAKES UP ALOT OF ROOM.

[Haitian_King]

Idk. I don't have a G35 so I'm just talking I guess. Either way, you'll find the FSM helpful. Have you tried asking around in the G35 forum?

[Haitian_King]

Did you fix the problem?

[tylojack]

its in the shop, one of the sensors, i dont know which one yet, but plan to find out, and will post it when i do!

[Haitian_King]

Good to know. Glad you're getting the problem solved. Nothing's better than an in-shape Infiniti!

[elwesso]

I would not be concerned about the reliability of your G35. They seem to be good cars, so I wouldnt lose sleep over it. These problems seem to be few and far between...

If I was in your mechanic's shoes I would check all the connections before I started replacing parts, I see that being mroe likely than an actual part failing.