Transmission not engaging properly

Good morning,

That is inaccurate information.

Engagement into either drive or reverse is mechanical, not electrical.

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

You need to have the fluid level checked first. If that is correct, I would change the fluid and filter as the filter may be clogged with debris.

https://www.2carpros.com/articles/how-to-service-an-automatic-transmission

I would try this first to see if that takes care of the issue. Beyond that, we need to see if there are any codes.

I posted a flow chart below with possibilities of the issue.

Roy

I attached the code description and some checks below. This code will not prevent it from going into gear.

You most likely have an issue with the front pump not producing enough pressure.

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

I attached the procedure for testing the line pressure to be sure it is the front pump.

Roy

Firm Transmission Shifts, Shudder/Chuggle, Transmission Wont Downshift on Deceleration, Service Engine Soon Light Illuminated, DTC P0742 Set (Perform Diagnostics and Replace TCC PWM Solenoid) # 02-07-30-039E - (Mar 10, 2005)

Models:
2003 Buick Century, LeSabre, Park Avenue, Regal, Rendezvous
1999-2002 Cadillac Eldorado
1999-2003 Cadillac DeVille, Seville
2003 Chevrolet Cavalier, Impala, Malibu, Monte Carlo, Venture
1999 Oldsmobile Aurora
2001-2003 Oldsmobile Aurora
2003 Oldsmobile Alero, Silhouette
2003 Pontiac Aztek, Bonneville, Grand Am, Montana, Sunfire
2003-2004 Pontiac Grand Prix

with 4T65E Transaxle (RPOs MN3, MN7, M15, M76), 4T40E/4T45E Transaxle (RPOs MN4 or MN5) or 4T80E Transaxle (RPO MH1)

with PWM Solenoid Manufacturing Julian Dates Between 219 and 3048

This bulletin is being revised to add an additional transaxle model to the parts information. Please discard Corporate Bulletin Number 02-07-30-039D (Section 07-Transmission/Transaxle).

Condition

Some customers may comment that the transmission shifts hard, a shudder/chuggle is felt on deceleration or the Service Engine Soon (SES) light is illuminated.

A technician may find DTC P0742 set.

Customers with 4T80E transaxles may also comment on a "bump" feeling at approximately 61-68 km/h (38-42 mph) when they lift and then tip into the throttle. There may also be a concern of whine noise in 3rd or 4th gear with or without the Service Engine Soon light/message displayed and with DTC P0742 set.

Correction

DO NOT REPLACE THE VALVE BODY AND PUMP ASSEMBLY.

Important:
This test is not applicable to the 4T80E transmission. Instead, replace the TCC PWM solenoid on vehicles with a 4T80E transmission using published procedures for the vehicle being serviced.

Perform one of the following diagnostics:

Test drive the vehicle with the Tech 2(R) installed, Monitor Transmission Release Pressure. The Status will be YES until TCC applies and then the display will read NO. If during acceleration the status remains NO and the upshifts are harsh and during deceleration the vehicle shudders during downshifts, suspect the TCC PWM solenoid.

With the Tech 2(R) installed in the vehicle, start the engine. Build the vehicle on the Tech 2(R). Apply and firmly hold the service brake. Place the transaxle in D4 and command Drive 3 with the Tech 2(R). If the engine stumbles and/or stalls, suspect the TCC PWM solenoid.

Replace the TCC PWM solenoid using published procedures for the vehicle being serviced.

Pressure test

Line Pressure Check Procedure

Tools Required
- J21867 Pressure Gage

Important:
- Before performing a line pressure check, verify that the pressure control (PC) solenoid valve is receiving the correct electrical signal from the PCM.
- Some conditions may be intermittent, therefore this test should be performed at least 3 times.

1. Install a scan tool.

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

2. Start the engine and set the parking brake.
3. Check for a stored Diagnostic Trouble Code (DTC).
4. Repair the vehicle, if necessary.
5. Check the fluid level.
6. Check the manual linkage for proper adjustment.

imageOpen In New TabZoom/Print

7. Turn the engine Off. Remove the oil pressure test hole plug and install the J21867.
8. Put the gear selector in PARK range and set the parking brake.
9. Start the engine and allow the engine to warm up at idle.

Notice: The total test running time should not be longer than 2 minutes. Running the test longer than 2 minutes may damage the transaxle.

10. Access the PC solenoid valve control test on the scan tool.
11. Increase the PC solenoid actual current from 0 to 1 amps in 0.1 amp increments. Allow the pressure to stabilize for five seconds after each pressure change. Read the corresponding line pressure on the J21867.
12. Refer to the Line Pressure specification table. Compare the data to the table.
13. If pressure readings differ greatly from the table, refer to Incorrect Line Pressure.
14. Shut the engine OFF. Remove the J21867.
15. Apply sealant GM P/N 12345382 (Canadian P/N 1095348) to the oil pressure test hole plug.

Notice: Refer to Fastener Notice in Service Precautions.

16. Install the oil pressure test hole plug.
Tighten the plug to 12 Nm (106 inch lbs.).

I also responded to your other post for the 133.

If you cannot perform any of the testing, you may need help in trying to determine the failure. Someone with a scan tool that can read the information for you.

Roy