Transmission acts like it is stuck in neutral

CHELL1976

MEMBER
2004 CHEVROLET TRAILBLAZER
4.2L
V6
4WD
AUTOMATIC
2,137,654 MILES

Two days ago my husband was pulling out and some one came up on our tail end pretty fast so he gave it some gas to get put of the way. We'll it went about 20 feet and then it would not go anymore. He pulled over and the head shot would go in to gear but all my car would do is rev up. It won't actually go. We have replaced both shift solenoids and the pressure solenoid and still nothing. Can some one please help me? I don't have another vehicle.

1 Reply

ASEMASTER6371

MECHANIC
52,797 POSTS

Good morning,

When the pan was dropped, was there any metal or debris in the pan or on the magnet?

https://www.2carpros.com/articles/automatic-transmission-problems

Are there any codes set in the system?

Does the truck have reverse?

The most common failure is the torque converter or the front pump inside the transmission.

Pressure tests need to be done to confirm there is no line pressure for the transmission to work. I attached the procedure and the chart for testing. You will need an advanced scan tool for this test plus a pressure gauge to attach to the transmission.

Roy

Line Pressure Check Procedure

Tools Required
J 21867 Pressure Gage

Caution: Keep the brakes applied at all times in order to prevent unexpected vehicle motion. Personal injury may result if the vehicle moves unexpectedly.

Important: Before performing the line pressure check, verify that the transmission Pressure Control (PC) solenoid is operating correctly.

1. Install a scan tool.
2. Start the engine.
3. Inspect the transmission for the proper fluid levels.
4. Use the scan tool to inspect for any active or stored diagnostic trouble codes.
5. Inspect the manual linkage at the transmission for proper function.
6. Turn the engine OFF.
7. Remove the pressure plug.
8. Install the J21867.
9. Access the Scan Tool Output Control for the PC Solenoid.
10. Start the engine.

Important: In order to achieve accurate line pressure readings, the following procedure must be performed at least three times in order to gather uniform pressure readings. The scan tool is only able to control the PC solenoid in PARK and NEUTRAL with engine speeds below 1500 RPM. This protects the clutches from extreme high or low line pressures.

11. Begin commanding PC Solenoid at 1.0 amp and lower the amperage in one-tenth increments (0.01) until maximum line pressure is achieved.
12. Allow the pressure to stabilize between increments.
13. Compare your pressure readings to the Line Pressure table.
14. If the pressure readings vary greatly from the line pressure table, refer to Oil Pressure High or Low.
15. Turn the engine OFF.
16. Remove the J21867.

Notice: Refer to Fastener Notice in Cautions and Notices.

17. Install the pressure plug.
Tighten the pressure plug to 8 - 14 Nm (6 - 10 ft. lbs.).

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