DTC : B2638

DTC B2638  : Front Left Sensor Bus Failure

DTC (Parking and Back-Up Sensor Control Unit)

NOTE:  If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A - Go to: Body Electrical Troubleshooting - B-CAN System Diagnosis Test Mode A - Initial Communication and DTC Checks .

1. Problem verification

   - 1. Clear the DTCs with the HDS.

   Clear DTCs

   - 2. Turn the vehicle to the OFF (LOCK) mode and then the ON mode.

   - 3. Turn the parking and back-up sensor switch to ON.

   - 4. Wait for at least 5 seconds.

   - 5. Check for DTCs with the HDS.

   DTC Description	DTC
   B2638 Front Left Sensor Bus Failure

   Is DTC B2638 indicated?

   YES 

   Go to step 2.

   NO 

   Intermittent failure, the system is OK at this time. Check for loose or poor connections.

2. DTC check

   - 1. Check for DTCs with the HDS.

   DTC Description	DTC
   B2638 Front Left Sensor Bus Failure
   B2641 Front Right Sensor Bus Failure

   Is DTC B2638 and/or B2641 indicated?

   YES 

   Go to step 3.

   YES 

   Go to step 6.

   NO 

   Check for loose or poor connections. If OK, replace the Parking and Back-Up Sensor Control Unit .

3. Left front corner sensor check

   - 1. Swap the left front corner sensor and the right front corner sensor. Front Corner Sensor

   - 2. Clear the DTCs with the HDS.

   Clear DTCs

   - 3. Turn the vehicle to the OFF (LOCK) mode and then the ON mode.

   - 4. Turn the parking and back-up sensor switch to ON.

   - 5. Wait for at least 5 seconds.

   - 6. Check for DTCs with the HDS.

   DTC Description	DTC
   B2638 Front Left Sensor Bus Failure

   Is DTC B2638 indicated?

   YES 

   Go to step 4.

   NO 

   Replace the original left Front Corner Sensor .

4. Shorted wire check (SOF L line to power)

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

   - 2. Disconnect the following connector.

   Left front corner sensor 6P connector

   - 3. Turn the vehicle to the ON mode.

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

   Test condition	Vehicle ON mode Left front corner sensor 6P connector: disconnected
   Test point 1	Left front corner sensor 6P connector No. 2
   Test point 2	Body ground

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

   Is there battery voltage?

   YES 

   Repair a short to power in the SOF L wire between the left front corner sensor and the parking and back-up sensor control unit.

   NO 

   The SOF L wire is not shorted to power, go to step 5.

5. Shorted wire check (SOF L line)

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

   - 2. Disconnect the following connector.

   Parking and back-up sensor control unit 24P connector

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

   Test condition	Vehicle OFF (LOCK) mode Left front corner sensor 6P connector: disconnected Parking and back-up sensor control unit 24P connector: disconnected
   Test point 1	Left front corner sensor 6P connector No. 2
   Test point 2	Body ground

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

   Is there continuity?

   YES 

   Repair a short to ground in SOF L wire between the left front corner sensor and the parking and back-up sensor control unit.

   NO 

   Repair an open or high resistance in SOF SIDE L wire between the left front corner sensor and the parking and back-up sensor control unit.

6. Open wire check (BOF L, E1 R lines)

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

   - 2. Disconnect the following connectors.

   Parking and back-up sensor control unit 24P connector

   Right front corner sensor 6P connector

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

   Test condition	Vehicle OFF (LOCK) mode Parking and back-up sensor control unit 24P connector: disconnected Right front corner sensor 6P connector: disconnected
   Test point 1	Parking and back-up sensor control unit 24P connector No. 2 - Refer to: Parking and Back-Up Sensor Control Unit Connector for Inputs and Outputs (2016 2017 2018) or Parking and Back-Up Sensor Control Unit Connector for Inputs and Outputs (2019 2020 2021) .
   Test point 2	Right front corner sensor 6P connector No. 6

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

   Is there continuity?

   YES 

   Repair an open or high resistance in E1 L wire between the parking and back-up sensor control unit and the right front corner sensor.

   NO 

   Repair an open or high resistance in BOF R wire between the parking and back-up sensor control unit and the right front corner sensor.