Transmission will not shift gears

Hi,

After you replaced the speed sensor, does the speedometer work properly?

I attached a pic of the VSS. Is this the sensor that was replaced? If it was, then I need you to have the can-bus scanned to determine if there are any stored codes. CAN stands for controller area network. Basically, all computers/modules are tied together via a few wires. We need to determine if there are codes in the TCM, transmission control module.

Here is a video showing how it's done.

https://youtu.be/u-4syLc-ifQ

Let me know. Also, let me know about the speedo and what the transmission does and the model of the transmission if you have it.

Take care,

Joe

See pic below.

The instrument cluster isn't working. But I put another one in, and it worked. It is a 4l60e transmission in 2003 GMC Sierra 4wd 5.3l. The transmission only holds 2nd and 4th gears. When I let off the gas, it will shift out then. I did a procedure to reset TCM. Still nothing.

Hi,

It sounds like there is a line pressure issue. When you replaced the transmission, did you install a new filter? If you did, was it securely seated in the valve body? There is an O-ring that people miss sometimes. If the old one isn't removed, it will cause a pressure issue.

If you look below, the pics provide the directions for testing line pressure.

Let me know if this helps or if you have other questions.

Take care,

Joie

See pics below.

I took the rebuilt transmission back out and put another good transmission in. When I tried running it, it is still only shifting in 2nd and 4th. Do I need new speed sensors? Is there a transmission temp range sensor? Or any other sensors I should change? Or grounds I should check? Or if I change PCM, TCM, computers out and gear box and flash them, would that make it right?

Hi,

If it is doing the same thing with a different transmission, it is likely related to the TCM or the transmission adaptive pressure functions (TAP).

First, pic 1 below shows the trans fluid temperature sensor. It is internal.

You mentioned the speed sensors. Is the speedo working properly? Are the sensors in this transmission from the old one? If not, I don't think that's the issue. Plus, if it were a speed sensor, it would cause all gear shifts to be off and not only use 2 and 4.

Pics 2 and 3 are the procedure for the adaptive relearn. It does require a scan tool that can communicate with the TCM.

Let me know if this helps.

Joe

If I put a new ECM and PCM in, will this fix my problem? I have traced wires back to transmission and can't find any wrong. My speedometer still doesn't work.

Hi,

I can't say if that will fix the problem. At this point, my primary focus would be why the speedo isn't working. The computer uses speed to determine shift points. If the signal isn't there, it won't shift properly.

The IPC (instrument panel cluster) displays the vehicle speed on the analog speedometer based on the vehicle speed signal from the PCM. It doesn't come straight from the VSS. If there is a breakdown in the wiring or communication between the VSS and PCM, we have a wiring issue or faulty VSS.

If the PCM receives a signal from the VSS and there is nothing sent from it to the IPC, then the PCM is the prime suspect.

I don't want to recommend replacing the PCM simply because we can't be certain that is the cause, and it isn't a cheap part.

Do you have a live data scan tool or access to one?

Let me know.

Joe