Line Pressure Check

Fig 1: Pressure Gage

Courtesy of GENERAL MOTORS CORP.

Special Tools 

GE 21867  Pressure Gauge

For equivalent regional tools, refer to Special Tools .

WARNING: Keep the brakes applied at all times in order to prevent unexpected vehicle motion. Personal injury may result if the vehicle moves unexpectedly.
1. Install a scan tool.
2. Start the engine.
3. Inspect the transmission for the proper fluid level. Refer to Transmission Fluid Level and Condition Check .
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.
NOTE: You may need to remove or disconnect components in order to gain access to the transmission line pressure test hole plug.
7. Remove the line pressure test hole plug.
8. Install the GE 21867:  pressure gauge.
9. Access the Scan Tool Transmission Output Controls for the Line PC Solenoid.
10. Start the engine.
NOTE:
• In order to achieve accurate line pressure readings, the following procedure should be performed at least three times.
• The values displayed on the scan tool screen will not match the actual pressures indicated on the pressure gauge.
• The scan tool is capable of commanding 200-700 Kpa. The 800 Kpa in chart below is a reference value only.
• Control the Line PC Solenoid in PARK or NEUTRAL with the engine speed at approximately 1500 RPM and the TFT between 35-55°C (95-131°F). This protects the clutches from extreme high or low line pressures and ensures a consistent pump capacity.

Use the scan tool to increase and decrease line pressure, allowing the pressure to stabilize between increments.

12. Compare the pressure readings on the gauge with the table below.
13. If the pressure readings on the gauge are erratic, or increment by more than what is indicated in the table below, refer to Fluid Pressure High or Low .
14. Turn the engine OFF.
15. Remove the GE 21867  pressure gauge.
CAUTION: Refer to FASTENER CAUTION .
16. Install the line pressure test hole plug. Tighten the pressure plug to 11 N.m (97 lb in).