Today I was getting onto the freeway after stopping at a stoplight and I quickly noticed the gear was not changing automatically. I clicked the gear lever into manual mode and saw the gear indication said 4. This is clearly wrong as I was almost redlining 1st while I got into the emergency lane. "Manual" gear mode was unresponsive (clicking forward [+] would not change gears). A/T light was flashing and check engine light was on as well (these were not on when I started the car).

I put the gear in park, turned the car off, waited a bit then turned it back on. A/T light was flashing and check engine light was on. Then, A/T light turned off. I then put the car in gear and merged onto the freeway. Everything seemed to be working fine, the gears change manually and automatically but the check engine light is on and now remains on.

This is on a 2004 350z with 135,000 miles and an automatic transmission. I did a search for this but came up short. A buddy of mine has a machine to read the error codes but does anyone have any advice to point me in the right direction on this? The strangest thing to me is that the car reported 4th gear when it was in 1st, I've never seen that before in any car.

 

what was the code?

 

Haven't hooked it up yet, will post when I see what it says. Thought since the symptom is very specific that it might be enough to diagnose.

 

Has the tranny been serviced at 30-40k intervals?

 

More like 50k, but yes. I had the fluid flushed 30k miles ago and checked when I serviced the car about 1k miles ago. There's no indication of mechanical issues while driving.

I've driven around since I posted and it seems to work fine but the check engine light is still on. A/T hasn't flashed since I turned on the ignition by the side of the freeway.

 

And stll havent got the code either i bet

 

P1774 - Low Coast Brake Solenoid Valve Function

 

AT = rocket science

Take it to a TRUSTED transmission shop.

 

WAIT......found this - https://www.autocodes.com/uploads/nissan/NTB10-003a.pdf

 

From what I'm reading this could be a connector to the Low Coast Brake Solenoid, the Low Coast Brake Solenoid control circuit is shorting out or stuck open, the Low Coast Brake Solenoid has failed, or the A/T pressure switch #2 has failed (or a combination of those issues).

I cleared the code, light is off, I'll see if it comes back.

Unfortunately I'm not familiar enough with this system to know the lowest cost solution if it does act up again. It's looking like it'll depend on if that control circuit and connector is replaceable or if it's part of the valve assembly.

 

Thanks, that led me to a video of repairing the circuit to the solenoid here:
Interesting in that flow chart they are calling to repair the circuit and not replace it.

Correct me if I'm wrong, but I'm looking for OEM# RE5R05A, Bosch # 0260550002 if I have to replace the board.

I can't find an OEM part number for the Low Coast Brake Solenoid, only that it's referenced as #9715.

If I can get away with replacing just the board and the solenoid I might be able to keep this job under $750.

Another thing to note, I have a hanging front right caliper. Not sure if this is related in any way related but the more info the better.

 

This^

Even when I went to Auto tech school when we got onto Auto transmissions I was always so lost and confused on how this black magic works.

 

What's blowing my mind is that they designed the control board to be submerged in transmission fluid after 2004 1/2 models, which includes mine. Before that the TCM was in the cabin. WHY?!?!?!

 

I love you ask this like IT guys ask “Have you restarted your computer yet?”

 

Hah, well technically yes I did restart the computer.

Code hasn't come back. Every piece of wood has been knocked on, all fingers crossed. Been taking it real easy driving around lately.

 

hey now i am IT and i, .... . well wait......i do say that alot

 

Do you refer to restarting as 'power cycling'?

 

Nope.... i tell people to get a running start and kick it.... my version of rebooting.

most of our employees work from home and use voip phone and the computer jumps internet off the phone. Biggest complaint is phone is choppy or citrix is freezing, usually internet issue.... but they dont understand restarting the modem usually resolves it