DTC U0101-00: Lost Communication With The PCM (PGM-FI System)

NOTE:

Before doing this troubleshooting procedure, find out if the vehicle was in a collision. If so, verify that all the requiredcomponents were replaced with new components, of the correct part number, and that they were properly installed .
Before doing this troubleshooting procedure, review SRS Precautions and Procedures , General Troubleshooting Information , and 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.

Check for any F-CAN and B-CAN communication DTCs with the HDS.
Are there any communication DTCs?

YES - Go to the appropriate DTC troubleshooting.

NO - Go to 2
Clear the DTCs with the HDS .
Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode, then wait for 10 seconds.
Clear the DTCs with the HDS .
Is DTC U0101-00 indicated?

YES - Go to step 5

NO - Intermittent failure, the system is OK at this time. Go to Troubleshooting Intermittent Failures . If another DTC isindicated, troubleshoot the DTC.
Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.
Start the engine, and see if the malfunction indicator lamp (MIL) also stays on.
Does the MIL stay on longer than 30 seconds?

YES - Go to the Fuel and Emissions Systems General Troubleshooting Information.

NO - Go to step 7.
Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.
Jump the SCS line with the HDS .
NOTE: This step must be done to protect the PCM from damage.
Disconnect PCM connector A (49P) from the PCM .
Disconnect the negative cable from the battery, then wait at least 3 minutes.
Disconnect SRS unit connector A (39P) from the SRS unit .
Check for continuity between SRS unit connector A (39P) terminal No. 6 and PCM connector A (49P) terminal No. 48,and between SRS unit connector A (39P) terminal No. 7 and PCM connector A (49P) terminal No. 49.

Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES - Faulty SRS unit or poor connection at SRS unit connector A (39P) and the SRS unit. Check the connectionbetween the connector and the SRS unit. If the connection is OK, replace the SRS unit . If the DTC does not clear, replacethe right engine compartment wire harness or the dashboard wire harness.

NO - Open in the harness between SRS unit connector A (39P) terminal No. 6 and PCM connector A (49P) terminalNo. 48, or between SRS unit connector A (39P) terminal No. 7 and PCM connector A (49P) terminal No. 49 (right enginecompartment wire harness or dashboard wire harness); replace the faulty harness, then clear the DTC.