DTC P177A

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

DTC (A/T)

1. 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 (2014 2015), or Automatic Transmission Removal and Installation (2016 2017 2018 2019 2020) .

   NO 

   Replace the ATF - Refer to: ATF Replacement (2014 2015), or ATF Replacement (2016 2017 2018 2019 2020) , then go to step 2.

2. 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 Pressure Switch signal with the HDS.

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

   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 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.

   NO 

   The failure is duplicated. Go to step 3.

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.

4. Fuse check

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

   - 2. Check the following fuse.

   Fuse	No. C3 (15 A)

   Location

   Under-hood fuse/relay box

   Is the fuse OK?

   YES 

   The fuse is OK. Go to step 5.

   NO 

   Replace the No. C3 (15 A) fuse, and recheck. If the fuse blows again, repair a short to ground on the No. C3 (15 A) fuse circuit, and recheck.

5. Open wire check (IG1 (VBSOL) line)

   -1. Jump the SCS line with the HDS.

   - 2. Disconnect the following connector.

   PCM connector B (51P) - Refer to: How to Troubleshoot the Brake Booster Pressure Monitoring System (2016 2017 2018 2019 2020), or How to Troubleshoot the Fuel and Emissions Systems(With Auto Idle Stop System) (2016), or How to Troubleshoot the Fuel and Emissions Systems, or How to Troubleshoot the A/T System (2014 2015)

   - 3. Turn the vehicle to the ON mode.

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

   Test condition	Vehicle ON mode
   	PCM connector B (51P): disconnected
   Test circuit	IG1 (VBSOL)
   Test point 1	PCM connector B (51P) No. 1 (TAN)
   Test point 2	Body ground

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

   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) .

   NO 

   Repair an open in the IG1 (VBSOL) wire between the PCM and the No. C3 (15 A) fuse in the under-hood fuse/relay box.

6. 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 (BRN)
   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
   	Values	Unit	Values	Unit
   Line Pressure Pressure Switch	ON

   Do the current condition(s) match the threshold?

   YES 

   Replace the line pressure switch .

   NO 

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

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.

   - 4. Disconnect the following connector.

   PCM connector B (51P) - Refer to: How to Troubleshoot the A/T System (2014 2015), or How to Troubleshoot the Fuel and Emissions Systems, or How to Troubleshoot the Brake Booster Pressure Monitoring System (2016 2017 2018 2019 2020), or How to Troubleshoot the Fuel and Emissions Systems(With Auto Idle Stop System) (2016)

   - 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 circuit	OPPLSW
   Test point 1	Line pressure switch 1P connector No. 1 (BRN)
   Test point 2	PCM connector B (51P) No. 37 (BRN)

   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 (2014 2015), or PCM Removal and Installation (2016) .

   NO 

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