Hello and welcome to JustAnswer!
P0706 is for the transmission range sensor. Depending on which transmission you have the range sensor is either mounted on top of the valve body or it is integral to the solenoid pack mounted on top the valve body. This code can set because of a bad range sensor, range sensor wiring problem or misadjusted shift cable.
P1790 is 'fault after shift' and has set because of the P0733, which sets when the trans controller sees a gear ratio error in third gear. It watches the input and output speed sensors to determine if each clutch applies correctly and gear ratio codes set when the signals don't agree.
Make sure your speed sensors got plugged in. If you have a 42RLE trans the input and output speed sensor connectors are the same and will reach the opposite sensor so it's possible to plug them in incorrectly.
The problem could also be a bad input or output speed sensor, they can be monitored on a scan tool.
Other than speed sensors and fluid level there are no other simple, external causes. If the overdrive clutch is slipping then this code will set, in which case an internal repair would be needed which should be covered under warranty if you just bought the unit.
I also forgot to mention that transmission fluid is coming out of the vent plug when you turn the engine on
Which engine do you have?
3.7 liter V6
You have the 42RLE trans then.
How much fluid did you put in total?
Do you know if the trans was dry when you started?
Does the fluid come out of the vent only when driving or it will it happen just with it sitting and idling?
IT happen idling in parking
i filled 8 quart of transmission fluid before i started the vehicle
i checked the level idling in neutral at cold and it was at the correct level
What exactly happens when you drive it? Does it initially have first and second gear and then slips or freewheels when it should go into third?
i could never drive it
it doesn't even move of an inch forward or backward
also when i shift the column lever i dont see the indicator gear indicate in which gear i am
i checked my shifter cable and everything is adjusted properly , even on the transmission side it is moving normal
Does it not engage in gear at all?
Is this a two wheel or four wheel drive truck? If it's four wheel drive then make sure the transfer case isn't in neutral.
If the transfer case is in two wheel drive, the fluid is full and shift cable is adjusted correctly then you have definite internal issues and I would recommend contacting the transmission supplier. They'll most likely send you another unit rather than having you trying to diagnose and repair their rebuilding mistakes.
it doesnt engage in any gear
it is a 4wd and i checked that it was not in neutral
i bought it from a company called " transmission depot in florida"
and they shipped it to my country in TAHITI 5000 MILES AWAY FROM FLORIDA
Do you think the warranty will work ?