'04 G35x .. Trans stuck in limp mode after engine swap.

[Heli-mech]

Hey guys,

I just finished helping a friend swap engines in his' 04 G35x , his old one had BAD valve seals and was burning oil like crazy. He decided to pick a low mile used engine, and a few of us from work decided to give him a hand swapping it out/in. We all work on aircraft for a living, but myself and another guy are big car guys and have been swapping and building cars & bikes for years.

Anyway evreytrhing went smoothly and the new swap runs great, but the auto trans is stuck in 3rd gear (limp mode) and is throwing p0744 code for the torque converter. He drove it over to a shop and had the transmission fluid flushed and refilled....with no luck.

He is now panicking thinking the transmission is destroyed. I myself think it is a wiring/sensor issue, or maybe a sensor on the new motor is throwing it off.

Anyway any ideas/input/advice are appreciated.

Cheers,
Ian

[sstroudwku]

744 is indicating the torque converter is not locking out. This is typically associated with a bad valve body, it could have been damaged during the install. However, check the wiring and make sure you guys didn't pinch, cut, or damage a wire or harness. If all is well in the wiring you can monitor the trans feed and see if the converter is locking out. Also, have you guys cleared the code with a scanner and try that? Sometimes it works too.

[Heli-mech]

Thanks for the reply Steve.

I cleared the code with a scanner and it came back immediately, we also reset the ecu and tried that with no luck. I will go over the wiring harness today after work. A few questions for you...

- Does Nissan have a specific method or code reader for pulling TCU specific trans CEL/MIL codes?
- Where is valve body located, externally or in the pan area of the trans?
- You can electronically monitor the trans feed to check for Tq converter lock up?

Thanks,
Ian