what does transmission range sensor do?

I know that TR sensor tells PCM the position of the shift lever (1,2,D,N,R,P) and it controls back up lights. Does it also report the gear transmission is in when driving in D (1-4)? Or is this a different sensor? I am talking about 4R55E transmission by the way from 96 X.

When I log gear number while driving I can see it changing from 1 to 4 and back. Sometimes, there is a mismatch between the gear reported and the actual gear, it reports 4 while the X is in 3rd gear. I beleive this causes my CEL problem. I'd like to know which sensor reports the gear number.

Thanks

What code # are you getting for the check engine light? The range sensor wouldn't be responsible for actual gear changes. That is related to other factors such as the input from the VSS, TPS, turbine speed sensor, etc. # 7 in my list of useful threads has more information: http://www.explorerforum.com/forums/showthread.php?t=157488

Hi BrooklynBay,

I do not think this thread applies to me. I have 96 with 4R55E transmission. The error code I am getting is P0761, which corresponds to the stuck solenoid C. I replaced it and it did not fix the problem. I just got OBD-2 scan tool and I am going to monitor transmission sensors when this error code is set. I know the conditions that can set the code, but I am not sure why it's set. I'll explain more when I get some scan data.

How does computer know the gear X is in? Does it command the gear to the transmission? How does it verify that transmission is in gear it's supposed to be (1-4)? Here is what I think happening in my case.

Driving at 55mph. Logger reports 4th gear requested by PCM. X is in 4th gear judging by PRMs (~1500). When I start going up a long hill, speed drops. I add gas a bit and I can feel transmission switching to 3rd, RMPs go up to ~2200, load ~40%. However, it appears (and I have to double check this tonight) that PCM still commands 4th gear judging by the logger. I think that's what causing a problem. I am going to double check all these tonight. I just got the scan tool and still learning how to use it. It displays so much data.

So, how does PCM know what gear (1-4) my X is in while driving? I thought it's TR sensor, but I might be wrong.

Thanks

This is why I recommeded reading post # 2. The computer sends a signal to a shift solenoid, the EPC solenoid, (and sometimes the TCC solenoid to vary lock up) to change gears, then uses a combination of sensors to see if it responded. If it didn't, then it could be a faulty servo piston, misadjusted band, sticking valve body spool, or possibly a faulty sensor not giving the computer the correct information (VSS, TPS, TSS, etc).

There is not a sensor that reports "gear number". The range sensor tells the PCM what YOU are commanding. From there the PCM relies on sensor inputs to command various gears - from that it knows what it expects.

Your issues sound sensor related.

Your understanding of the TRS is correct.

I've been logging for wo days and I cannot make CEL to come on I am sure it'll be back the moment I stop logging. A question, which sensors do you recommend logging for code P0761? It's a code for SSC solenoid, but I know it is not a fault since I've replaced it already and I can see it switching back and forth while driving. I am going to just bands next to see if it helps.

Thanks

Well, sure enough the first day I was driving w/o logger CEL came up again. Same code P0761. All gears (including OD) were working fine before and after CEL. That's killing me. I think I am just going to drive around with logger plugged in all the time. Can you recommend me parameters worth logging? If it try to log all sensors (~300) sampling rate will be horrible.

Thanks