Post by
srwood11 »
https://forums.nicoclub.com/srwood11-u167368.html
Sat Jun 07, 2014 10:15 am
This seems to be a common problem with the I35's. I ended up fixing it (for now) in the process of troubleshooting. I believe it was stuck because of failure to change the transmission fluid by the previous owner (I had not yet serviced the transmission since purchasing). In mine (2004 I35), it was throwing the P0745 code, and shifting hard between 1st and 2nd.
I started following the troubleshooting steps in the FSM. I checked the drop resister first, and it was good - 12 ohms. Next I dropped the transmission pan and tested the line pressure solenoid value. This is easy to do. The value is on the opposite side from the set of shift valves. The inside harness unclips easily from the connector where it enters the sealed transmission area.
I checked the solenoid valve resistance on Pin #4. It was good. 2.5 to 5 ohms range.
Then, also using pin #4, I applied 12 volts from a small batter charger. I applied on and off about 12 times and listened for the clicking sound each time. All sounded good, but unknowingly, this apparently freed up the stuck solenoid. Based the schematic, the current flows through the dropping resistor. I think that applying full current from the charger freed up the solenoid.
I didn't have time to proceed with the remaining steps, so I put it back together, and gave it fresh synthetic tranny fluid with a bottle of Lucas transmission conditioner. I haven't had a problem since (been over a month).