DTC P177A (16-20 6-Speed A/T)

DTC P177A : Line Pressure Solenoid Valve A Or Line Pressure Switch Stuck OFF

NOTE: Before you troubleshoot, review the General Troubleshooting Information - Refer to: How to Troubleshoot the A/T System (6-Speed A/T) .

DTC Description	Confirmed DTC	Pending DTC	Freeze Frame
P177A Line Pressure Solenoid Valve A Or Line Pressure Switch Stuck OFF

DTC (A/T)

ATF check
- 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 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 - Refer to: Automatic Transmission Removal and Installation (6-Speed A/T) .

NO

Replace the ATF, then go to step 2. - Refer to: ATF Replacement (6-Speed A/T)

Problem verification

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

- 2. Turn the vehicle to the ON mode.

- 3. Clear the DTC with the HDS.

- 4. Start the engine.

- 5. Monitoring the APP Sensor (%) with the HDS, 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 Switch signal with the HDS.

Signal	Current conditions
Signal	Values	Unit
APP Sensor (%)
Line Pressure Sol VLV. A
Line Pressure Switch

Is the Line 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 and loose terminals between the line pressure switch and the PCM. If the freeze data/on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the freeze data/on-board snapshot.

The failure is duplicated. Go to step 3.

Determine possible failure area (IG1 (VBSOL) line, others)
- 1. Select the Line Pressure Solenoid Test in the Miscellaneous Test Menu, and check that line pressure solenoid valve A operates with the HDS.

Line Pressure Solenoid Test

Is a clicking sound heard?

YES

Go to step 6.

NO

Go to step 4.
Fuse check
- 1. Turn the vehicle to the OFF (LOCK) mode.

- 2. Check the following fuse.

Fuse No. C7 (15 A)

Location Under-dash fuse/relay box

Is the fuse OK?

YES

The fuse is OK. Go to step 5.

NO

Replace the No. C7 (15 A) fuse, and recheck. If the fuse blows again, repair a short to ground on the No. C7 (15 A) fuse circuit, and recheck.

Open wire check (IG1 (VBSOL) line)

- 1. Jump the SCS line with the HDS, and wait more than 1 minute.

- 2. Disconnect the following connector.

PCM connector B (51P)

- 3. Turn the vehicle to the ON mode.

- 4. Measure the voltage between test points 1 and 2.

Test condition	Vehicle ON mode
Test condition	PCM connector B (51P): disconnected
Test point 1	PCM connector B (51P) No. 1 - Refer to: PCM Connector for Inputs and Outputs (16-20 6-Speed A/T)
Test point 2	Body ground

Is there battery voltage?

YES

The IG1 (VBSOL) wire is OK. Faulty line pressure solenoid valve A. Replace the secondary valve body (line pressure solenoid valve A) .

Repair an open in the IG1 (VBSOL) wire between the PCM and the No. C7 (15 A) fuse in the under-dash fuse/relay box.

Line pressure switch check

- 1. Turn the vehicle to the OFF (LOCK) mode.

- 2. Disconnect the following connector.

Line pressure switch 1P connector

- 3. Connect terminals A and B with a jumper wire.

Terminal A	Line pressure switch 1P connector No. 1
Terminal B	Body ground

Courtesy of HONDA, U.S.A., INC.

- 4. Turn the vehicle to the ON mode.

- 5. Check the parameter (s) below with the HDS.

Signal	Threshold		Current conditions
Signal	Values	Unit	Values	Unit
Line Pressure Switch	ON

Do the current condition (s) match the threshold?

YES

Replace the line pressure switch .

The line pressure switch is OK. Go to step 7.

Open wire check (OPPLSW line)

- 1. Turn the vehicle to the OFF (LOCK) mode.

- 2. Remove the jumper wire.

- 3. Jump the SCS line with the HDS, and wait more than 1 minute.

- 4. Disconnect the following connector.

PCM connector B (51P)

- 5. Check for continuity between test points 1 and 2.

Test condition	Vehicle OFF (LOCK) mode
	Line pressure switch 1P connector: disconnected
	PCM connector B (51P): disconnected
Test point 1	Line pressure switch 1P connector No. 1
Test point 2	PCM connector B (51P) No. 37 - Refer to: PCM Connector for Inputs and Outputs (16-20 6-Speed A/T)

Courtesy of HONDA, U.S.A., INC.

Is there continuity?

YES

The OPPLSW wire is OK. Replace the PCM - Refer to: PCM Removal and Installation (6-Speed A/T, 16-18 9-Speed A/T) .

Repair an open in the OPPLSW wire between the line pressure switch and the PCM.