Transmission does not shift?

First, are you certain you properly installed the filter and the small o-ring where the filter fits into the valve body? It sounds like that has come apart and the fluid is not circulating. Thus, it cannot shift into any gear. I assume you checked fluid level and it is full. Remember, the fluid is checked with the engine warm, running and then you can remove the fill plug to make sure the level is at the bottom of the hole.

What type of transmission fluid did you put back in?

I was afraid of that. The correct fluid should have been Dexron VI. The newer fluid has different friction modifier additives. Pouring the wrong fluid can ruin the transmission.

I learned that the hard way with a Toyota. Spec called for T-IV and added Dexron III and after transmission failed.

At this point you may want to look into replacing the unit and flushing out the cooler lines to prevent contamination.

Good afternoon,

Do you mean it will not move the shifter from park?

Can you be more specific?

Roy

Welcome to 2CarPros.

The idea that the speedometer isn't working indicates an issue with the vehicle speed sensor (VSS). The sensor's signal is used to determine shift points. Have you replaced the VSS or checked wiring to it?

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There are two different possible automatic transmissions used on this vehicle. I am going to provide the directions for replacing the VSS for both. You should be able to identify the transmission that matches yours by the pictures. All attached pictures correlate with the directions.

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2005 Chevrolet Cobalt L4-2.2L VIN F
MU3
Procedures MU3

Vehicle Speed Sensor (VSS) Replacement

Removal Procedure

1. Remove the left front wheel.

Pic 1

2. Disconnect the vehicle speed sensor (VSS) electrical connector (2).

Pic 2

3. Remove the retainer bolt.
4. Remove the retainer.
5. Remove the VSS.
6. Remove and discard the O-ring.

Installation Procedure
1. Lubricate a new O-ring with DEXRON III transmission fluid Saturn P/N 121019223.
2. Install the new O-ring.

Pic 3

3. Install the VSS retainer. Install the vehicle speed sensor (VSS) assembly.

4. Notice: Refer to Fastener Notice in Service Precautions.

Install the VSS retainer bolt.
Tighten the bolt to 9 Nm (80 inch lbs.).

Pic 4

5. Connect the VSS connector to the VSS (2).
6. Install the left front wheel.

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2005 Chevrolet Cobalt L4-2.2L VIN F
4T40-E/4T45-E

Vehicle Speed Sensor (VSS) Replacement

Removal Procedure

1. Caution: Refer to Battery Disconnect Caution in Service Precautions.

Disconnect the negative battery cable from the battery negative terminal.
2. Raise and support the vehicle.
3. Remove the electrical connector at the vehicle speed sensor.

Pic 5

4. Remove the retaining stud and the sensor. Pull straight out in order to avoid damage to the case.

Installation Procedure
1. Clean and dry the vehicle speed sensor.

Pic 6

2. Notice: Install the vehicle speed sensor and the retaining bolt.

Tighten the stud to 12 Nm (97 inch lbs.).
3. Install the electrical connector at the sensor.
4. Remove the safety stands.
5. Lower the vehicle.
6. Connect the negative battery cable.
Tighten the terminal bolt to 15 Nm (11 ft. Lbs.).

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

Take care,
Joe

Welcome back:

I didn't realize the jumper cables were reversed. Chances are the TCM was damaged. Regardless, I'm glad to hear it's working again.

Let us know if you have questions in the future.

Take care,
Joe