DTC P1673: Motor Control Module (MCM) Relay Stays Activated

NOTE:

Before you troubleshoot, record all freeze data, and any on-board snapshot, and review the general troubleshooting information (see GENERAL TROUBLESHOOTING INFORMATION ).
If the DTC cannot be cleared, do the troubleshooting for DTC U1204.
If DTC P1673 is stored, 12 V battery may be discharged.

Turn the ignition switch to ON (II).
Clear the DTC with the HDS (see DTC CLEAR ).
Turn the ignition switch to LOCK (0), and wait at least 40 seconds. Turn the ignition switch to ON (II) again.
Check for Pending or Confirmed DTCs with the HDS.
Is DTC P1673 indicated?

YES -Go to step 5.

NO -Intermittent failure, the system is OK at this time.
Turn the ignition switch to LOCK (0).
Turn the battery module switch OFF (see TURNING OFF AND ON POWER TO THE HIGH VOLTAGE CIRCUIT ).
Remove the IPU cover (see IPU COVER REMOVAL/INSTALLATION ).
Remove MCM relay 1 (A).

Fig 1: Identifying MCM Relay 1 Components Location
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Measure the voltage between IPU relay holder (MCM relay 1) 8P connector terminals No. 7 and No. 8.

Fig 2: Measuring Voltage Between IPU Relay Holder (MCM Relay 1) 8P Connector Terminals No. 7 And No. 8
Courtesy of AMERICAN HONDA MOTOR CO., INC.

When turning the ignition switch from ON (II) to LOCK (0), does the voltage change from 10 V to 0V?

YES -Go to step 10.

NO -Go to step 11.
Test MCM relay 1 (see POWER RELAY TEST ).
Is the relay OK?

YES -Repair a short to power in the wire between MCM relay 1 and the MCM (A9), then go to step 14.

NO -Replace MCM relay 1, then go to step 14.
Remove the PCU lid, the PCU busplate, and the PCU cover (see IPU CASE REMOVAL/INSTALLATION ).
Disconnect MCM connector A (31P).
Check for continuity between MCM connector terminal A3 and body ground.

Fig 3: Checking Continuity Between MCM Connector Terminal A3 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair a short to ground in the wire between MCM relay 1 and the MCM (A3), then go to step 14.

NO -Go to step 21.
Reconnect all connectors.
If removed, reinstall the PCU cover, the PCU busplate, and the PCU lid (see IPU CASE REMOVAL/INSTALLATION ).
If removed, reinstall the IPU cover (see IPU COVER REMOVAL/INSTALLATION ), then turn the battery module switch ON (see TURNING OFF AND ON POWER TO THE HIGH VOLTAGE CIRCUIT ).
Turn the ignition switch to ON (II).
Clear the DTC with the HDS (see DTC CLEAR ).
Turn the ignition switch to LOCK (0), and wait at least 40 seconds. Turn the ignition switch to ON (II) again.
Check for Pending or Confirmed DTCs with the HDS.
Is DTC P1673 indicated?

YES -Check for poor connections or loose terminals at MCM relay 1 and the MCM, then go to step 1.

NO -Troubleshooting is complete. If any other Pending or Confirmed DTCs are indicated, go to the indicated DTC'S TROUBLESHOOTING .
Reconnect all connectors.
Reinstall the PCU cover, the PCU busplate, and the PCU lid (see IPU CASE REMOVAL/INSTALLATION ).
Reinstall the IPU cover (see IPU COVER REMOVAL/INSTALLATION ), then turn the battery module switch ON (see TURNING OFF AND ON POWER TO THE HIGH VOLTAGE CIRCUIT ).
Update the MCM if it does not have the latest software (see MOTOR CONTROL MODULE (MCM) UPDATE ), or substitute a known-good MCM (see SUBSTITUTING THE MCM ).
Turn the ignition switch to ON (II), and then to LOCK (0). Wait at least 40 seconds, then turn the ignition switch to ON (II) again.
Check for Pending or Confirmed DTCs with the HDS.
Is DTC P1673 indicated?

YES -If the MCM was updated, substitute a known-good MCM (see SUBSTITUTING THE MCM ), then recheck. If the MCM was substituted, go to step 1.

NO -If the MCM was updated, troubleshooting is complete. If the MCM was substituted, replace the original MCM (see IPU CASE REMOVAL/INSTALLATION ). If any other Pending or Confirmed DTCs were indicated, go to the indicated DTC'S TROUBLESHOOTING .