Line Pressure Check. Cadillac Concours 1997

For 1990-2009 cars

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:

Gear Range | Line Pressure Range
--- | ---
Drive, Park or Neutral | Minimum line 50-55 psi, Maximum line 230-250 psi
Reverse | Minimum line 90 psi, Maximum line 300 psi

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

1. Hook up the scan tool.
2. Start the engine and set the parking brake.

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

3. Check for a P0748 malfunction code from the pressure control solenoid of the stored transmission. Check for other malfunction codes.
4. Repair the vehicle if necessary. Include the following areas:

• | Inspect the fluid level

• | Inspect the manual linkage at the transmission

• | Install the line pressure gage.

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. Enter the diagnostics routine and select MISC TESTS.
8. Select A/T OUTPUTS-PC SOLENOID.
9. Increase the transmission fluid pressure by commanding low amperage. Read the corresponding line pressure on the pressure gage.
10. Compare your data to the Drive-Park-Neutral line pressure chart below. This line pressure is valid for PC solenoid overrides with the vehicle stopped at idle and in Park-Neutral.

If your pressure readings differ greatly from the line pressure chart, refer to Symptom Tables.