Vehicle moves forward
Vehicle does not go backwards.
Vehicle throws codes related to accelerator pedal position sensor.
I didn't work on that so I am stupified.
I have checked the service manual and it seems to me that two things could be responsible for this state of affairs.
Failure to replace transmission lip seal
Failure to reprogram the TCM
Are these ideas on the mark?
Any and all advice would be appreciated.
I ran the gamut of tests specified and arrived at the conclusion that the stepper motor was indeed bad.
So it was determined that replacing the stepper motor would be the way to go, and so it was replaced.
But the DTC P1777 did not go away.
This goes against the grain of Nissan Motor Company to replace the entire valve body in the event of a stepper Motor failure
So next the entire valve body was replaced as suggested by Nissan
But P1777 did not go away.
That raises a few questions:
The service manual wanted the lip seal to be taken down as part of disassembly and also reinstalled as part of reassembly, see pictures below:
Note that the instruction is silent on replacing the old lip seal with a new lip seal, which makes the requirement to remove and reinstall the lip seal appear superfluous, unlike in the related but upgraded transmission with very similar characteristics in which the instructions were patently clear, remove the old lip seal and replace with a new lip seal
For those who do not know, this is the only information I could find on the open internet on the role of lip seals in transmissions
If you take the time to read up the link above, you will appreciate that
Automatic transmission seals are used to contain pressure and prevent leakage.
When we compare that with this other quote from a third party repair manual for the very same transmission in question, it seems that the problem is hydraulic, and is linked to pressure losses
This extract describes the operation of the vehicle in reverse. The question is this? Is it that the forward clutch is not released? Is it that the reverse brake is not engaged?
If you carefully study the pictures of the location of the lip seal in question, it seems to match the picture of the Reverse apply in the following picture!
It is instructive to note that after replacing the valve body the vehicle attempted to reverse then got stuck and stopped reversing!
That is the detailed backstory...so the question the lack of reverse is it attributable to the non-replacement of the lip seal or is it connected to TCM initialization after valve body replacement?