Bad transmission sensor?

[Wyatt.bilodeau]

So I had my Speedo jump from 60 to 30 the other day which I just figured it was a stepper motor and would be an easy fix in the cluster, until the transmission started getting stuck in gear and not shifting right. I’ve done some research and to my understanding there are 3 speed sensors on the transmission and one on the transfer case which is the VSS. I ended up replacing the sensor on the transfer case today but didn’t seem to fix the issue. I guess my question is how do I know which one is bad out of the 3 on the transmission? Can I do an OHMs test on them even though the problem is not happening consistently?

 

[Chevy1925]

its not a trans sensor causing your issue. what did the end of the old sensor look like? how many miles are on your truck?

typically this is a sign of a transfercase issue. not always 100% the issue but something with that tcase speed sensor is screwing with your shifting and speed. have you checked for any codes? sometimes you get an incorrect ratio code from the TCM as well.

 

[Wyatt.bilodeau]

its not a trans sensor causing your issue. what did the end of the old sensor look like? how many miles are on your truck?

typically this is a sign of a transfercase issue. not always 100% the issue but something with that tcase speed sensor is screwing with your shifting and speed. have you checked for any codes? sometimes you get an incorrect ratio code from the TCM as well.

I got a 0700 code right after the poor shifting which is a communication error between the trans and TCM to my understanding. The truck has 250k on it and the old sensor definitely looked pretty old. The one I replaced is the one that screws into the rear of the t case

 

[Chevy1925]

I got a 0700 code right after the poor shifting which is a communication error between the trans and TCM to my understanding. The truck has 250k on it and the old sensor definitely looked pretty old. The one I replaced is the one that screws into the rear of the t case

no, p0700 means the TCM has told the ECM to turn the MIL on as there are stored codes in the TCM that need to be checked. if you couldnt find more p07xx codes, your scan tool is not good enough to see them, sadly.

im betting you have a worn out t-case that is allowing the output shaft to move around and cause the sensor to loose readings. you will need to pull the TCM codes before jumping farther though. could be a wiring issue.

 

[Wyatt.bilodeau]

no, p0700 means the TCM has told the ECM to turn the MIL on as there are stored codes in the TCM that need to be checked. if you couldnt find more p07xx codes, your scan tool is not good enough to see them, sadly.

im betting you have a worn out t-case that is allowing the output shaft to move around and cause the sensor to loose readings. you will need to pull the TCM codes before jumping farther though. could be a wiring issue.

How would I go about pulling the tcm codes?

 

[Chevy1925]

How would I go about pulling the tcm codes?

get a better scan tool that can read them. they will automatically come up if the scanner has the ability to access the tcm.

 

[Wyatt.bilodeau]

get a better scan tool that can read them. they will automatically come up if the scanner has the ability to access the tcm.

Okay I will try to find a tuner with that capability. I use my ppe tuner to read my codes currently