As I sit here tonight I want to share a moderately severe issue that I experienced about 3 years ago. I was not active on the forums at that time, but want to share this so that others who experience this problem can benefit from my research and labor.

I was sitting in a parking lot one mild Florida evening for a little over an hour. I was completing a report and was letting the Z idle with the AC on so as not to succumb to the agony of Florida summers. As I shift the car to “D” to drive home I felt the car lurch and the CEL illuminated. The car exhibited sluggish acceleration the entire drive home. I had entered “Limp Mode”.

I got home and pulled the codes with my scanner. I received DTC P1757 and P1759. Both of these relate to the Front Brake Solenoid.

The Front Brake Solenoid is located inside of the transmission on the valve body. The Transmission Control Module controls the Front Brake Solenoid and uses signal input from the PNP switch, Vehicle Speed Sensor, and Throttle Position Sensor to select, and ensure, the optimum gear at all times.

Here are the symptoms that I experienced when this fault occurred:

- You will experience a “bang” or lurch, followed by a loss of power as the car enters Limp mode

- Sluggish acceleration (due to car starting and staying in 4th gear as a result of Limp Mode)

- Manual Mode will not let you upshift or downshift from 4th gear

- 3k max RPM during driving

- If standing still while in “D’”, the car will not roll forward if you take your foot off the brake

- Reverse does not seem to be affected

- When the vehicle is powered on and started the “A/T” light will flash for a few seconds

You can reset the code with your scanner, or turn the car off and back on, but the problem will persist until repaired.



*Disclaimer and Before-Hand Tips*

It is important to note that the problem I faced may not be the reason for your fault, but seems to be the most common. If your fault is related specifically to the FBS being bad and needing replacement then that is much more expensive as Nissan does not sell these solenoids separately, but only as a whole in conjunction with the valve bodies. Should you decide to disassemble your transmission and attempt the repair posted below, realize that you do it at your own risk and that no one is liable for any damage you may receive as a result.



*Repair*

I contacted Nissan and was told that the TCM would most likely need to be replaced and reprogrammed. I was looking at roughly $1,200 at least for a repair bill and would be without the car for at least a day. I hate taking my car to the stealership so I began researching the issue. I found the most common cause of the DTC is due to a cracked circuit pin on the circuit board of the TCM. If you are mechanically inclined, you can complete this repair for roughly $120, plus the price of beer, and can reasonably complete this repair in about 3 hours, give or take.

I do not recommend this for anyone who is not confident in their mechanical abilities, or who does not have a comfortable handling on soldering.

You will need:

- Basic tool set with ratchet and sockets

- 10 QTS of transmission fluid

- Soldering iron and solder

- Jack and jack stands

OPTIONAL:

Small floor jack or bottle jack that can fit under the car and a microfiber towel


Here is a basic rundown of the steps:


- Ensure vehicle is cool. I recommend letting it sit overnight



- Disconnect the negative battery terminal cable and secure away from battery


- Jack the front of the vehicle up and place on jackstands



- Remove the transmission drain bolt and drain the fluid into a container. (About 10 QTS)



- (OPTIONAL) Jack up the rear of the vehicle and place it on jack stands (makes it more

comfortable)



- Remove the bolts (10 mm, I believe) holding the pan to the bottom of the transmission.



- Disconnect the green, braided, 3-wire connector and let it hang



- Remove the bolts holding the valve body in place



- Lower the valve body slightly and carefully (it has a decent weight to it)



- Unplug the connector for the Transmission Control Module



- Unbolt the TCM from the valve body. Place the valve body somewhere safe (Good time to send off to have a Transgo kit installed, just saying!)



- CAREFULLY, CAREFULLY, CAREFULLY, use a small flathead screwdriver or other thin utensil to separate the body of the TCM



- Locate the connector pin leading to the FBS and inspect for damage



- If cracked, apply a very small amount of solder to the pin. Inspect and confirm that solder is solid and properly affixes pin ends



- Carefully, place both sides of your TCM back together and snap closed



- Bolt TCM back to valve body



- This is where that small floor / bottle jack come in. I folded the microfiber towel into 1/4s, placed it on top of the jacks, and used the jack to lift and hold the valve body in place. Trust me, when you’re laying on your back, trying to hold that heavy valve body in place and bolt it back is a PITA. Don’t forget to plug the TCM back in!



- Bolt valve body back in place



- Bolt pan back to bottom of transmission



- Fill with 10qts (10.3, actually) of transmission fluid



- Reconnect the battery and you are good to roll again!



Unfortunately, I did not take pics as I did not believe I would ever be posting this to the forum, however listed below is the EXACT video I followed while doing this. It is completed on a G35, but will work just the same.






Hopefully this helps someone in the future!