P0745 transmission solenoid

[fsbaksh82]

Hi
SES light came on with P0745, line pressure solenoid vault. My car is shifting hard especially from neutral to drive, and also jerks when driving slow. Is the solenoid going bad and needs to be replaced, it has 180K miles (2001 I30). How much work is involved? What else should I look for? What are your experiEnces with this? Thanks

[maxhopper]

I would check the drop resistor first. It is on the driver side strut tower. Make sure that is plugged in and there is no damage to the wires.

See here starting on page AT-166. http://www.nicoclub.com/FSM/I30/2001/at.pdf

[srwood11]

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).

[fsbaksh82]

It was the drop resistor. I bought it for around $20 and that fixed it! It has been 3 months and no problems.

[Baby]

fsbaksh82,
Where did you get the drop resistor for $20. My dealer wants $80
Thanks