I don't know much about Automatic Transmission internal operations. I can find stuff in the manual but I don't always know how useful or relevant it is.The torque converter clutch solenoid valve is activated, with the gear in D4 , D5 by the TCM in response to signals sent from the vehicle speed sensor and accelerator pedal position sensor (throttle position sensor). Torque converter clutch piston operation will then be controlled.
● Lock-up operation, however, is prohibited when A/T fluid temperature is too low.
● When the accelerator pedal is depressed (less than 1/8) in lock-up condition, the engine speed should not change abruptly. If there is a big jump in engine speed, there is no lock-up.
I can assure that it locks in 3rd. At least on my 08 it does, also the programming Nissan doesFrom the 2007 Service Manual:
I don't know much about Automatic Transmission internal operations. I can find stuff in the manual but I don't always know how useful or relevant it is.
Of course 4th is better. 5th gear is an overdrive gear. Not ever a good idea to tow in an overdrive gear.I'm pretty sure I've seen the same behavior in 4th. Possibly in 3rd. There are times I wish I had a manual transmission.
If what I found and what you're saying is true then the rule of thumb to tow in 4th isn't much better than towing in 5th. At least that's my take on it.
I'll be looking at it tonight in the FSM for 2008. I've been thoroughly reading the 2007 FSM already. If you're right I'll gladly accept it with a smile on my face....knowledge is power.Never tow in 5th. The simple way to do this is to watch the tach, it will tell you what is going on, try this, when towing up hill put it in 3rd and use a steady pedal, dont try this with a heavy load. Try a steady speed with rpms about 2k, then push on the gas, not hard or it will downshift, it will break free of lock up and start to slip. It does the same in 4th. I always change my fluid at 30k completely or partial at 15k. I tow heavy, much easier to see all this with a heavy load.