Line Pressure Check Procedure

Line Pressure Check

Line Pressure Check:

Special Tools

J 21867 - Pressure Gage



Warning

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



Note

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. Refer to Transmission Fluid Check (4L60-E/4L65-E/4L70-E Automatic Transmission) .
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

It may be necessary to remove or disconnect components in order to gain access to the transmission line pressure test port/plug.

7. Remove the pressure plug.
8. Install the J 21867 - gage .
9. Access the Scan Tool Output Control for the PC Solenoid.
10. Start the engine.


Note

* 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.
* This test must be preformed at 1200 RPM, between 38-93°C (100-200°F).


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. Refer to Line Pressure (Pressure, Vacuum and Temperature Specifications) .
14. If the pressure readings vary greatly from the line pressure table, refer toOil Pressure High or Low (Oil Pressure High or Low) .
15. Turn the engine OFF.
16. Remove the J 21867 - gage .
Caution: Refer to Fastener Caution (Fastener Caution) .
17. Install the pressure plug. Tighten the pressure plug to 8-14 Nm (6-10 lb ft) .