Transmission/TCM Issue - Need some advice
Hi TT, first and foremost, thanks for all the great info. I've been reading/using this site for years and typically I'm able to find the info I need without posting any questions.
This time it's different: I can't find anything that is a definite answer. My previous attempts at fixing my issues have all failed and cost me time and money.
MY ISSUE: no overdrive. Shifts from 1 to 2 to 3 to 4 to 3 again. Repeatable at about 40 MPH. If I manually shift into 4th, my T drives fine. I just have no overdrive.
Vehicle and History: I have a 2006 Nissan Titan LE, 4x4 crew cab with the tow package and 206K miles on it. I used the crap out of my Titan and it's been a great vehicle. At about 165K miles, I lost the transmission clutch and had it rebuilt. I live on a dirt road and the seals apparently failed. Prior to this, I've also replaced the fuel pump and taken my T to the dealer for recalls as needed. I'm the original owner and purchased it in Jan of 06 with 7 miles.
From reading/troubleshooting, I've done the following:
1. Changed transmission filter and fluid - checked fluid level
2. Replaced the valve body - used design 3 though design 2 came standard
3. Replaced all solenoids - again, from the design 3
4. Replaced the throttle body and took to dealer for reset
That's the order in which I've done everything so far but I still have no overdrive. My T drives a little different now but still has great power and can still pull heavy trailers, etc.
My concern and I hope the obvious solution: will the TCM from the design 2 work with the design 3 valve body and solenoids? My guess is the solenoids have different ohm outputs and the TCM may falsely interpret the signals.
BUT, but: I changed the valve body and solenoids to design 3 from design 2 and nothing really changed: other than I spent time and money but still have no overdrive.
My "newest" guess/conclusion: change the TCM. I have the design 3 TCM on hand but I didn't change it when I changed the valve body and the solenoids because the little springs that were on design 2 were not on design 3.
Here's a reference to see the difference between the 2 designs: http://www.makcotransmissionparts.com/mm5/graphics/00000001/RE5R05A-MECHATRONIC-CONTROL-ASSY.jpg design 2 springs in the area that says "verify tcm design" - the yellow arrow is pointing right at the springs.
This one is design 3: http://www.makcotransmissionparts.com/mm5/graphics/00000001/P63740-5-t.jpg the "number 2" is circling the area that does not have springs.
I can easily change out the TCM with the design 3 TCM vice the currently installed design 2 tcm (which I now believe may be my issue) but I'm concerned about the springs.
Back to my original issue: do you think the TCM is the cause of my issue? And... can I install the design 3 TCM as it is?
Oh - to be clear: I am not a mechanic but I'm also not afraid to tear into stuff and try to fix it on my own. I try to do my research but I sometimes get it wrong.
Thanks for taking the time to read and respond for my benefit.
Hi TT, first and foremost, thanks for all the great info. I've been reading/using this site for years and typically I'm able to find the info I need without posting any questions.
This time it's different: I can't find anything that is a definite answer. My previous attempts at fixing my issues have all failed and cost me time and money.
MY ISSUE: no overdrive. Shifts from 1 to 2 to 3 to 4 to 3 again. Repeatable at about 40 MPH. If I manually shift into 4th, my T drives fine. I just have no overdrive.
Vehicle and History: I have a 2006 Nissan Titan LE, 4x4 crew cab with the tow package and 206K miles on it. I used the crap out of my Titan and it's been a great vehicle. At about 165K miles, I lost the transmission clutch and had it rebuilt. I live on a dirt road and the seals apparently failed. Prior to this, I've also replaced the fuel pump and taken my T to the dealer for recalls as needed. I'm the original owner and purchased it in Jan of 06 with 7 miles.
From reading/troubleshooting, I've done the following:
1. Changed transmission filter and fluid - checked fluid level
2. Replaced the valve body - used design 3 though design 2 came standard
3. Replaced all solenoids - again, from the design 3
4. Replaced the throttle body and took to dealer for reset
That's the order in which I've done everything so far but I still have no overdrive. My T drives a little different now but still has great power and can still pull heavy trailers, etc.
My concern and I hope the obvious solution: will the TCM from the design 2 work with the design 3 valve body and solenoids? My guess is the solenoids have different ohm outputs and the TCM may falsely interpret the signals.
BUT, but: I changed the valve body and solenoids to design 3 from design 2 and nothing really changed: other than I spent time and money but still have no overdrive.
My "newest" guess/conclusion: change the TCM. I have the design 3 TCM on hand but I didn't change it when I changed the valve body and the solenoids because the little springs that were on design 2 were not on design 3.
Here's a reference to see the difference between the 2 designs: http://www.makcotransmissionparts.com/mm5/graphics/00000001/RE5R05A-MECHATRONIC-CONTROL-ASSY.jpg design 2 springs in the area that says "verify tcm design" - the yellow arrow is pointing right at the springs.
This one is design 3: http://www.makcotransmissionparts.com/mm5/graphics/00000001/P63740-5-t.jpg the "number 2" is circling the area that does not have springs.
I can easily change out the TCM with the design 3 TCM vice the currently installed design 2 tcm (which I now believe may be my issue) but I'm concerned about the springs.
Back to my original issue: do you think the TCM is the cause of my issue? And... can I install the design 3 TCM as it is?
Oh - to be clear: I am not a mechanic but I'm also not afraid to tear into stuff and try to fix it on my own. I try to do my research but I sometimes get it wrong.
Thanks for taking the time to read and respond for my benefit.
