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Discussion Starter #1
I’m having a strange problem with my 2007 Taurus.


I am trying to change the Transmission Range Sensor (Neutral switch)- When I put in a new one (I’ve tried two so far)...The the new switch/sensor will allow the car to start in PARK but, not in neutral. Just dead flat when I turn the key, no cranking, nothing.


When I return to the old sensor to the car, the car starts in both Park and Neutral. I’m trying to switch the old sensor-switch out as I’m getting the ‘check transmission" on screen, and a code for defective Range Sensor comes up on the OBD.


I’ve double checked the alignment both with a tool, and just eyeball the lines on the switch. I’ve also checked the harness, but as I said, it works in both park and neutral with the older switch.


Is there some kind of calibration or other step to let the car know a new part is installed?


Thanks to all.
 

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You can use Forscan to see what gear the PCM thinks the tranny is in.

Did you use a good quality replacement TRS or some no name junk from the discount parts store? What code or codes did you get?
 

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Discussion Starter #3
Duralast TRS from Autozone. I can't justify why old one will start in neutral but new ones will not. What is Forscan? I forgot the code I was getting....I reset it when I pulled the battery. I'm back to using the old unit, and can induce the code at will-- by accelerating fast (instead of slow build up of speed)-- the car will go up to 3000 RPM's at 20mph and code will trigger.
 

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Forscan is a free download for PC very powerful OBDII program that allows you to see all classes of codes (P, C, B, U), PIDs, graph PIDs etc. All you need is a $25 or so ELM327 OBDII interface module (Amazon, Ebay, etc). I use one that has "the switch" to allow access to the MSCAN BUS. Can also download a slightly less powerful version for your phone, iPad, etc for around $5 from your app store that will connect with your device via wireless of bluetooth.

Likely your no start in N issue is the crap Durafail TRS. I wont buy any AZ electrical parts unless it is an absolute emergency.
 

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Discussion Starter #5
I downloaded the software and will play with it. I didn't know that AutoZone parts were so bad. I may just return it. I just found it odd that I had one with the same problems couple of months ago....but from someone on line (ebay)-- I chalked that up to bad electronics from the internet. I was wondering if there is a calibration that needs to be done to tell the PCM that there is a new switch (like, run through all gears, or let car idle in for 2 minutes, or something like that)--


Does the PCM 'remember' the gear that the car was in last?
 

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I downloaded the software and will play with it. I didn't know that AutoZone parts were so bad. I may just return it. I just found it odd that I had one with the same problems couple of months ago....but from someone on line (ebay)-- I chalked that up to bad electronics from the internet. I was wondering if there is a calibration that needs to be done to tell the PCM that there is a new switch (like, run through all gears, or let car idle in for 2 minutes, or something like that)--


Does the PCM 'remember' the gear that the car was in last?
I would put in in "N" turn the key to start and move the shifter a bit each way and see if it is just a slight adjustment. It is a mechanical switch for "P" and "N". A closed switch tells the PCM OK to crank.


-chart-
 

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Discussion Starter #7
I would put in in "N" turn the key to start and move the shifter a bit each way and see if it is just a slight adjustment. It is a mechanical switch for "P" and "N". A closed switch tells the PCM OK to crank.


-chart-

Thanks for writing: yes, i tried that also...I thought the same thing, slight adjustment, etc. I returned the Duralast TRS to Autozone. I will buy another one and try again. I was afraid to put the car in a 'gear' and turn the key because I recall the old days when a manual would cause the car to lurch ...but I may have to.
 

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Discussion Starter #9 (Edited)
The steps you've taken leads me to believe that the range sensor isn't necessarily the problem. I would verify the continuity from the switch to the PCM.

I will purchase a new TRS this week and try it again. What gets me is that it starts in Park and Neutral with the OLD unit. If all units failed to start in Neutral, it could point that way. Does anyone know of a wiring diagram/pin-out for the harness so I can do a check? I was thinking there maybe something with the wiring harness but it is bundled in heavy wrap so I'd rather not open it yet.



Even though I've been able to reproduce the ' check transmission light on the dashboard, no codes are being stored yet. I think it was a P0706 code back when it happened. Instead of writing it down, I told myself I"d remember it---LOL-- An old manager once told me " a short note is better than a long memory ".... Right he was.
 

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Discussion Starter #10
So i purchased yet another TRS and installed it with the same results. No start in Neutral. I looked again at the one I took out and saw that the alighnment markings were a little off... about 5 degrees left of the line inscribed line. I moved the 'new' one a few degrees and , you guessed it, -- car starts in Neutral! -- Now this scares me! Do I need to tell the transmission to re-learn anything? I purchased a OBDII reader for my PC and downloaded ForScan but can't find a way to use ForScan to determine what gear the PCM 'think's I am in. Can anyone give me instructions on that? Should I be resetting anything via ForScan?
 

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No need to reset anything with Forscan.

I know you can see what gear is selected (P, R, N, D, L) with Forscan as well as see what gear the tranny is operating in (Reverse, 1st, 2.d, 3d, 4th) as well as fluid temp, % TC lockup and a few other tranny related things. I havent looked at that stuff for a few years so I dont remember exacty where it was, but they are in there somewhere...... look at the LONG list of PIDs you can view.
 

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Discussion Starter #12
No need to reset anything with Forscan.

I know you can see what gear is selected (P, R, N, D, L) with Forscan as well as see what gear the tranny is operating in (Reverse, 1st, 2.d, 3d, 4th) as well as fluid temp, % TC lockup and a few other tranny related things. I havent looked at that stuff for a few years so I dont remember exacty where it was, but they are in there somewhere...... look at the LONG list of PIDs you can view.
LOL--- Jeff, you were by big hope! I bought the scanner and down loaded ForScan on your recommendation, so I was figuring you would know it inside and out! LOL-- So where are the PIDs listed--I dont' see them?
-Do you know if there are any ForScan 'experts' on the board? i really wanna 'reset' the trans/PCM etc, but scared I'm gonna kill my car if I do!
All I've done with ForScan is connect to the PCM and as able to back up my current settings. Freaked out a little by how powerful it is, and the damage someone inexperienced can do.
 

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Discussion Starter #13
But, I still can't come to grips with the fact that the alignment is not working. I bought the special tool, no less, and I have to still dial it about 5 degrees left of center to get the car to start in Neutral, which to me, tells me the PCM/Computer MIGHT Not be seeing the correct position reading from the TRS. Does that make sense? That is why I was asking if there is some type of 'resetting' to let the car know " THIS IS NEUTRAL" "THIS IS PARK" etc.
 

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TRS/NSS has a few mechanical switches inside it. Zero fancy electronics involved. The switches are either ON or OFF. No need for any kind of PCM reset or calibration of any kind. If the engine starts in neutral and park, and the gear selector (PRNDL) works correctly (i.e., OD selected it shifts 1 thru 4, D selected it shifts 1 thru 3, etc) you do not have a problem.
 
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