Transmission problems

Hi and welcome back.

Since it is working (cold) the first suspect I have is line pressure. There is a pressure control/regulator solenoid that may be failing. The pressure regulator solenoid is attached to the control valve body within the transmission. I attached a picture for you to see where (approximately) it is located.

Here are the directions for testing line pressure. Picture 2 shows where the line pressure tap is for the transmission and picture 3 shows what pressures should be based on gear selection and a specific temperature.

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Line pressures are calibrated for two sets of gear ranges - Drive-Park-Neutral, and Reverse. This allows the transmission line pressure to be appropriate for different pressure needs in different gear ranges:

Drive, Park or Neutral - 55-189 psi
Reverse - 64-324 Psi

Before performing a line pressure check, verify that the pressure control solenoid for the transmission is receiving the correct electrical signal from the PCM:

1. Install a scan tool.

CAUTION: Keep the brakes applied at all times in order to prevent unexpected vehicle motion.

NOTICE: The transmission may experience harsh, soft or mushy shifts for up to two days later.

2. Start the engine and set the parking brake.
3. Check for diagnostic trouble codes, including the diagnostic code for a stored pressure control solenoid.
4. Repair the vehicle if necessary. Include the following areas:
- Inspect the fluid level
- Inspect the manual linkage at the transmission
- Install or connect the TECH 1 scan tool.
- Install or connect the oil pressure gage at the line pressure tap.
5. Put the gear selector in Park and set the parking brake.
6. Start the engine and allow the engine to warm up at idle.
7. Access the PCS Control test on the TECH 1 scan tool.
8. Increase DESIRED PCS in 0.1-amp increments. Read the corresponding line pressure on the pressure gage. Allow the pressure to stabilize for five seconds after each current charge.
9. Compare your data to the Drive-Park-Neutral line pressure chart below.

If your pressure readings differ greatly from the line pressure chart, refer to the DIAGNOSIS CHARTS.

The TECH 1 scan tool is only able to control the pressure control solenoid in Park and Neutral with the vehicle stopped. This protects the clutches from extremely high or low pressures in Drive or Reverse ranges. (Pic3)
The pressures in the table assume an engine speed of 1500 RPM and a temperature of 66° C (150° F). The pressure will vary with a change in temperature.

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Check this first and let me know what you find.

Take care,
Joe

I will watch for your response. Take care,

Joe