DTC U1220 (34): DC-DC Converter Lost Communication with Motor Control Module (MCM)

WARNING: This page is about a different car, the 2011 Honda Insight and 2010 Honda Insight. However, it is still accessible from the selected car via links, so may be relevant.

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 (55).

Turn the ignition switch to ON (II).
Clear the DTC with the HDS (see DTC CLEAR ).
Start the engine.
Monitor the OBD STATUS for DTC U1220 (34) in the DTCs MENU with the HDS.
Does the screen indicate FAILED?

YES -go to step 5.

NO -If the screen indicates PASSED, intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the DC-DC converter and the MCM. If the screen indicates NOT COMPLETED, go to step 3 and recheck.
Turn the ignition switch to LOCK (0).
Turn the battery module switch OFF (see DISCONNECTING THE MOTOR POWER CABLE CONNECTOR FROM THE MOTOR STATOR ).
Remove the IPU cover (see IPU COVER REMOVAL/INSTALLATION ).
Remove the MCM (see MOTOR CONTROL MODULE (MCM) REMOVAL/INSTALLATION ).
Disconnect the DC-DC converter 4P connector (A).

Fig 1: Identifying DC-DC Converter 4P Connector
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Check for continuity between MCM connector terminal A26 and body ground.

Fig 2: Checking Continuity Between MCM Connector Terminal A26 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair a short in the wire between the MCM (A26) and the DC-DC converter, then go to step 22.

NO -go to step 11.
Reconnect the DC-DC converter 4P connector.
Turn the ignition switch to ON (II).
Measure the voltage between MCM connector terminal A26 and body ground.

Fig 3: Measuring Voltage Between MCM Connector Terminal A26 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there about 8-12 V?

YES -go to step 29.

NO -go to step 14.
Measure the voltage between DC-DC converter 4P connector terminal No. 2 and body ground.

Fig 4: Measuring Voltage Between DC-DC Converter 4P Connector Terminal 2 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there 8-12 V?

YES -Repair an open in the wire between the MCM (A26) and the DC-DC converter, then go to step 24.

NO -go to step 15.
Substitute a known-good DC-DC converter (see DC-DC CONVERTER REMOVAL/INSTALLATION ).
Reconnect all connectors.
Reinstall the MCM (see MOTOR CONTROL MODULE (MCM) REMOVAL/INSTALLATION ).
Reinstall the IPU cover (see IPU COVER REMOVAL/INSTALLATION ), then turn the battery module switch ON (see DISCONNECTING THE MOTOR POWER CABLE CONNECTOR FROM THE MOTOR STATOR ).
Turn the ignition switch to ON (II).
Clear the DTC with the HDS (see DTC CLEAR ).
Check for Pending or Confirmed DTCs with the HDS.
Is DTC U1220 (34) indicated?

YES -go to step 32.

NO -Replace the original DC-DC converter (see DC-DC CONVERTER REMOVAL/INSTALLATION ), then go to step 22.
Reconnect all connectors.
Reinstall the MCM (see MOTOR CONTROL MODULE (MCM) REMOVAL/INSTALLATION ).
Reinstall the IPU cover (see IPU COVER REMOVAL/INSTALLATION ), then turn the battery module switch ON (see DISCONNECTING THE MOTOR POWER CABLE CONNECTOR FROM THE MOTOR STATOR ).
Turn the ignition switch to ON (II).
Clear the DTC with the HDS (see DTC CLEAR ).
Check for Pending or Confirmed DTCs with the HDS.
Is DTC U1220 (34) indicated?

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

NO -go to step 28.
Monitor the OBD STATUS for DTC U1220 (34) in the DTCs MENU with the HDS.
Does the screen indicate PASSED?

YES -Troubleshooting is complete. If any other Pending or Confirmed DTCs were indicated in step 27, go to the indicated DTC's troubleshooting.

NO -If the screen indicates FAILED, check for poor connections or loose terminals at the DC-DC converter and the MCM, then go to step 1. If the screen indicates NOT COMPLETED, keep the ignition switch ON (II) until a result comes on.
Reconnect all connectors.
Reinstall the MCM (see MOTOR CONTROL MODULE (MCM) REMOVAL/INSTALLATION ).
Reinstall the IPU cover (see IPU COVER REMOVAL/INSTALLATION ), then turn the battery module switch ON (see DISCONNECTING THE MOTOR POWER CABLE CONNECTOR FROM THE MOTOR STATOR ).
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).
Check for Pending or Confirmed DTCs with the HDS.
Is DTC U1220 (34) indicated?

YES -Check for poor connections or loose terminals at the DC-DC converter and the MCM. If the MCM was updated, substitute a known-good MCM (see SUBSTITUTING THE MCM ), and recheck. If the MCM was substituted, go to step 1.

NO -go to step 35.
Monitor the OBD STATUS for DTC U1220 (34) in the DTCs MENU with the HDS.
Does the screen indicate PASSED?

YES -If the MCM was updated, troubleshooting is complete. If the MCM was substituted, replace the original MCM (see MOTOR CONTROL MODULE (MCM) REMOVAL/INSTALLATION ). If any other Pending or Confirmed DTCs were indicated in step 34, go to the indicated DTC's troubleshooting.

NO -If the screen indicates FAILED, check for poor connections or loose terminals at the DC-DC converter and the MCM. If the MCM was updated, substitute a known-good MCM (see SUBSTITUTING THE MCM ), and recheck. If the MCM was substituted, go to step 1. If the screen indicates NOT COMPLETED, keep the ignition switch ON (II) until a result comes on.