DTC U0155-00: Lost Communication With the Gauge Control Module (SRS Unit, With CAN gateway)

NOTE: 

• Before doing this troubleshooting procedure, find out if the vehicle was in a collision. If so, verify that all the required components were replaced with new components of the correct part number, and that they were properly installed - Refer to: SRS Component Replacement/Inspection After Deployment (2015-17) or SRS Component Replacement/Inspection After Deployment (2018-19) .
• Before doing this troubleshooting procedure, review SRS Precautions and Procedures , General Troubleshooting Information - Refer to: How to Troubleshoot the SRS (2015-17) or How to Troubleshoot the SRS (2018-19) , and 12 Volt Battery Terminal Disconnection and Reconnection .
• Before replacing the SRS unit, check the SRS unit software version with the HDS. If the software version is not the latest, update the SRS unit software , and retest.

DTC (SRS)

1. CAN gateway system DTC check

   -1. Turn the vehicle to the ON mode.

   - 2. Check for CAN gateway system DTCs with the HDS.

   DTC Description	DTC
   U0029-00 CAN Gateway F-CAN ch A Bus Off

   DTC Description	DTC
   U0047-00 CAN Gateway F-CAN ch B Bus Off
   U3000-49 CAN Gateway Internal Failure

   Is DTC U0029-00, U0047-00, and/or U3000-49 indicated?

   YES 

   Go to the troubleshooting for CAN gateway system DTC(s) - Refer to: Communication Systems DTC Troubleshooting Index (V6, With CAN gateway, 2015-17) or Communication Systems DTC Troubleshooting Index (2018-19) .

   NO 

   Go to step 2.

2. F-CAN circuit communication check

   -1. Select the FUNCTION TEST in the CAN gateway with the HDS, then select the F-CAN Bus Connected Unit Check.

   F-CAN Bus Connected Unit Check

   Which result is indicated?

   GAUGE CONTROL MODULE is Not Available

   Go to step 3.

   SRS UNIT is Not Available

   Go to step 4.

   GAUGE CONTROL MODULE and SRS UNIT are Detected

   Intermittent failure, the system is OK at this time. Go to Troubleshooting Intermittent Failures - Refer to: How to Troubleshoot the SRS (2015-17) or How to Troubleshoot the SRS (2018-19) . If another DTC is indicated, troubleshoot the DTC.

3. Open wire check (F-CAN A_H, F-CAN A_L lines)

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

   - 2. Disconnect the following connectors.

   Gauge control module 32P connector

   CAN gateway 24P connector

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

   Test condition	Vehicle OFF (LOCK) mode
   	CAN gateway 24P connector: disconnected
   	Gauge control module 32P connector: disconnected
   Test point 1	CAN gateway 24P connector No. 14
   Test point 2	Gauge control module 32P connector No. 27 - Refer to: Gauge Control Module Input Test (2015-17) or Gauge Control Module Input Test (2018-19)

   Test point 1	CAN gateway 24P connector No. 15
   Test point 2	Gauge control module 32P connector No. 28 - Refer to: Gauge Control Module Input Test (2015-17) or Gauge Control Module Input Test (2018-19)

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

   Is there continuity?

   YES 

   The F-CAN A_H and F-CAN A_L wires are OK. Check for poor connections or loose terminals at the CAN gateway and the gauge control module. If the connection is OK, replace the gauge control module .

   NO 

   Repair an open in the wire between the gauge control module and the CAN gateway.

4. Open wire check (F-CAN A_H, F-CAN A_L lines)

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

   - 2. Disconnect the negative cable from the 12 volt battery, then wait at least 3 minutes.

   - 3. Disconnect the following connectors.

   SRS unit connector A (39P)

   CAN gateway 24P connector

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

   Test condition	Vehicle OFF (LOCK) mode
   	SRS unit connector A (39P): disconnected
   	CAN gateway 24P connector: disconnected
   Test point 1	SRS unit connector A (39P) No. 20 - Refer to: SRS Unit Connector for Inputs and Outputs (2015-17) or SRS Unit Connector for Inputs and Outputs (2018-19)
   Test point 2	CAN gateway 24P connector No. 14

   Test point 1	SRS unit connector A (39P) No. 21 - Refer to: SRS Unit Connector for Inputs and Outputs (2015-17) or SRS Unit Connector for Inputs and Outputs (2018-19)
   Test point 2	CAN gateway 24P connector No. 15

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

   Is there continuity?

   YES 

   The F-CAN A_H and F-CAN A_L wires are OK. Check for poor connections or loose terminals at the CAN gateway and the SRS unit connector A (39P) of the SRS unit. If the connection is OK, replace the SRS unit - Refer to: SRS Unit Removal and Installation (2015-17) or SRS Unit Removal and Installation (2018-19) .

   NO 

   Replace an open in the wire between the CAN gateway and the SRS unit.