2005 Infinity G35 coupe automatic

Hey guys- so I know what the P1757 front brake solenoid code usually means for these cars. My car goes into limp mode and locks into 4th gear. Occasionally it will drive and shift fine, but will not go into 5th/overdrive. I have been planning on cracking open the valve body and looking for a cracked circuit and replacing the FB solenoid if it's bad.

However I got the car scanned the other day to double check the codes before getting into the repair, and I had a ton of codes showing - all of them voltage/circuit related, but I am wondering if I may have more problems than what I was expecting.

I am getting codes for irregular battery voltage, torque converter circuit voltage irregular, and I think solenoid voltage irregular on top of the fb solenoid code. I will get the exact code numbers and post them when I get off work.

These SEEM like they would still all be caused by the cracked circuit in the valve body?

Can anyone tell me if these are normal codes to see when having this issue or do I have more troubleshooting to do than I originally anticipated?

 

I had this same issue a couple of years ago. However, the only code my car displayed was the P1757 and one other (can't remember it, but was FBS related). Realize though that the crack is usually within the transmission control module located on the valve body, not the valve body itself. I would advise dropping the VB, removing the TCM and cracking it open. You will most likely fin the crack on the pin where it exits the TCM. Fix that it see if the issue is resolved. If not, then work on the others after.

Just a heads up, you cannot simply buy a new FBS. You can only get one by buying it along with all the other solenoids attached to a valve body unless you get lucky and find one on eBay, which is usually unlucky.

Here is an EXCELLENT video that will help. It is what I used to fix my problem and I have not had it return since I fixed it about 4 years ago.

 

I know alllll about the FBS fix and what it entails, my questions are my for the other codes I am experiencing - are they attributed to the crack in the circuit or am i going to have other problems to sort out?

Thank you for your helpful information regardless, that video is the one I've been referencing since i first found out about this problem 😉👍

I'm just worried I'm going to fix the cracked circuit and/or FBS and still have issues.

Btw I have In entire spare valve body with solenoids off a 03 coupe. I know the VBs are different (tcm), I grabbed it for the solenoid set in case I needed the FBS.

 

If the other problems are unrelated then it won't matter, you will still need to fix the FBS / TCM circuit. They could be related, they could not. That's why I suggested fixing the P1757 code first and seeing If they clear as well. That is the only way you will know for sure.

What other codes are you getting anyway? You never posted them

 

Yes I'm definitely fixing the FBS/ circuit either way. I just figured this is such a common issue maybe someone would know if these other codes come up as well when the circuit is cracked or if I might have a headache ahead of me...

The other codes are -

P1759 -FBS

P1757 FBS

P1754 Input clutch solenoid - FBS, faulty solenoid operation

P0744 torque converter clutch circuit intermittent ( says it
can be attributed to faulty solenoid or circuit as well...)

P1815 - manual mode switch - says it trips when tcm detects impossible input pattern .. so I suppose that is the FBS as well, trans jumps gears to 4th into limp mode I suppose that's an impossible input

P1765 - transmission 12v control relay... again bad voltage from circuit could be causing

C1109 - battery voltage irregular. No idea on this one, suppose it could also be attributed to the bad circuit throwing all the electrical off but idk.

These are my thoughts (hopes maybe lol) it seems like they all could be due to the circuit disconnect, it also works intermittently and the car shifts fine sometimes so it could be arcing out and connecting/disconnecting causing more electrical weirdness to be detected.

The car is in really great condition for its age, engine bay is clean enough to eat off of previous owner was a elderly woman.

Any thoughts are appreciated