P177A

DTC Troubleshooting: P177A (190-1)

DTC P177A:

Line Pressure Solenoid Valve A Stuck OFF, or Line Pressure Switch Stuck OFF

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot with the HDS, and review General Troubleshooting Information How to Troubleshoot the A/T System.

1. Warm up the engine to normal operating temperature (the radiator fan comes on).

2. Make sure that the transmission is filled to the proper level, and check for fluid leaks.

3. Drain the ATF ATF Replacement through a strainer. Inspect the strainer for metal debris or excessive clutch material.

Does the strainer have metal debris or excessive clutch material?

YES -

Replace the transmission.�

NO -

Replace the ATF ATF Replacement, then go to step 4.

4. Turn the ignition switch to ON (II).

5. Clear the DTC with the HDS.

6. Raise the vehicle on a lift, make sure it is securely supported, and allow all four wheels to rotate freely.

7. Start the engine. With the brake pedal pressed, shift to D, then release the brake pedal.

8. Monitoring the APP Sensor (%) with the HDS in the A/T Data List, press (2 % opened) and release (0 % opened) the accelerator pedal every 2 seconds. Then check the Line Pressure Sol VLV. A signal and the Line Pressure Pressure Switch signal with the HDS in the A/T Data List.

Is the Line Pressure Pressure Switch ON when Line Pressure Sol VLV. A is ON, and OFF when Line Pressure Sol VLV. A is OFF?

YES -

Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals between the line pressure switch and the PCM.�

NO -

Go to step 9.

9. Select Line Pressure Solenoid A in the Miscellaneous Test Menu, and check that line pressure solenoid valve A operates with the HDS.

Is a clicking sound heard?

YES -

Go to step 16.

NO -

Go to step 10.

10. Turn the ignition switch to LOCK (0).

11. Check for a blown No. 18 (15 A) fuse in the driver's under-dash fuse/relay box.

Is the No. 18 (15 A) fuse OK?

YES -

Go to step 12.

NO -

Repair a short to body ground in the wire between PCM connector terminal B2 and the driver's under-dash fuse/relay box.�

12. Jump the SCS line with the HDS.

13. Disconnect PCM connector B (49P).

14. Turn the ignition switch to ON (II).

15. Measure the voltage between PCM connector terminal B2 and body ground.





Is there battery voltage?

YES -

Faulty line pressure solenoid valve A. Replace the secondary valve body (line pressure solenoid valve A) Secondary Valve Body Replacement.�

NO -

Repair an open in the wire between PCM connector terminal B2 and the driver's under-dash fuse/relay box.�

16. Turn the ignition switch to LOCK (0).

17. Disconnect the line pressure switch connector.

18. Connect a jumper wire between the line pressure switch connector terminal and body ground.






19. Turn the ignition switch to ON (II).

20. Check the Line Pressure Pressure Switch signal with the HDS in the A/T Data List.

Is the Line Pressure Pressure Switch ON?

YES -

Replace the line pressure switch Line Pressure Switch Replacement.�

NO -

Go to step 21.

21. Turn the ignition switch to LOCK (0).

22. Remove the jumper wire.

23. Jump the SCS line with the HDS.

24. Disconnect PCM connector C (49P).

25. Check for continuity between PCM connector terminal C35 and the line pressure switch connector terminal.





Is there continuity?

YES -

Replace the PCM Service and Repair.�

NO -

Repair an open in the wire between PCM connector terminal C35 and the line pressure switch.�