94 Pathfinder stuck in Fail-Safe (limp home) mode

[Jacklalanne]

I have posted on this previously, but thought I would repost since I have done more since then in the way of diagnostics/research and am thinking it might help to get some fresh eyes on the subject as I can't imagine I am the only one here that has ever had to deal with this issue.

I have a 1994 Nissan Pathfinder that, according to what I can find in the AT FSM (and my owner's manual) is stuck in Fail-Safe (Limp home mode). I tried removing and replacing the positive battery cable. I also tried performing the on board diagnostics, but after the last step of the process I get no series of code flashes from the "Power" light as I should, indicating the issue. The symptoms, as described in the diagnostics that I have been able to find so far: 3rd gear in all positions except "1" (with 2nd gear in that position) seem to point to that specific problem, that is : Limp-home mode. I have also checked all pin voltages on the TCM with all coming up normal except pins 15 and 16 which are the pins for the "revolution sensor". At those pins I should have 1 volt or less, gradually rising as you gain speed. I get a flat zero volts. I have tried it three different times with my wife driving as I check the pins with the same result all three times. As I said all other pins read within normal tolerances.

I have been told by some ppl that if the RS is the problem I would still have reverse, and by others that since I don't have 1st gear (only 2nd gear in the first gear position and 3rd in all other positions except "Park") that I shouldn't necessarily expect to have reverse since 1st and reverse gears are run off of the same component (gear?) in the transmission. I wanted to check the resistance on the connections at the other end of the wire coming from the "revolution sensor" for proper resistance: 550-600 ohms between pin one and two and ∞ between pins 1 and 3 and also 2 and 3, but when I visually follow the wire along the top of the transmission, I can see where it goes out of sight sort of alongside the tranny dipstick and up the engine compartment side of the firewall, but for the life of me when I get up on top (I have literally crawled on top of the engine with a flashlight) I cannot pick it up visually to trace it to where its connector terminates. I would assume it ends up at the little tree of electrical connections on the right wheel well, but can't see any wires there that match the gauge or color of the wires when they leave the sensor. I would just replace the sensor, but in the first place as I said I can't even find where it terminates, and also the engineers in their wisdom placed it right on top of the transmission just in front of the transfer case in the 94-96 models (maybe others as well) and you have to drop down the transmission to access it. Additionally, it is almost a $200 part and if it turns out not to be the problem I am out a couple hundred bucks and a lot of wasted effort.

Any help with this problem would be greatly appreciated. Thanks in advance.
Regards,

Russ