DTC P1647 (5): Mode Signal Circuit 1 Low Input; DTC P16B7 (5): Mode Signal Circuit 1 Low Input

NOTE:

Information marked with an asterisk (*) applies to 2005-2006 models.
Information marked with double asterisk (**) applies to 2000-2004 models.

Reset the MCM (see HOW TO RESET THE MCM ).
Turn the ignition switch ON (II).
Is DTC P1647 (5)** (P16B7 (5)*) indicated?
1. YES - Go to step 3.
2. NO - Intermittent failure, system is OK at this time. Check for poor connections or loose terminals at the ECM and at the MCM.
Turn the ignition switch OFF.
Turn the battery module switch OFF (see TURNING OFF POWER TO THE HIGH VOLTAGE CIRCUIT ).
Remove the IPU lid (see TURNING OFF POWER TO THE HIGH VOLTAGE CIRCUIT ).
Check for continuity between body ground and MCM connector terminal C12.

Fig 1: Checking Continuity Between Body Ground And MCM Connector Terminal C12
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?
1. YES - Go to step 7.
2. NO - Substitute a known-good MCM, turn the battery module switch ON, and recheck. If the symptom/indication goes away, replace the original MCM.
Disconnect MCM connector C (31P).
Check for continuity between body ground and MCM connector terminal C12.

Fig 2: Checking Continuity Between Body Ground And MCM Connector Terminal C12
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?
1. YES - Go to step 9.
2. NO - Substitute a known-good MCM and recheck. If the symptom/indication goes away, replace the original MCM.
Disconnect ECM connector D (16P).
Check for continuity between body ground and MCM connector terminal C12.

Fig 3: Checking Continuity Between Body Ground And MCM Connector Terminal C12
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?
1. YES - Repair short to ground in the wire between the MCM (C12) and the ECM (D6).
2. NO - Substitute a known-good ECM; 2000-2001 models (see HOW TO SUBSTITUTE THE ECM FOR TESTING PURPOSE (2000-2001 M/T MODELS) ), 2002-2006 models (see ECM UPDATING AND SUBSTITUTION FOR TESTING-2002-2006 M/T MODELS AND CVT MODEL ), turn the battery module switch ON, and recheck. If the symptom/indication goes away, replace the original ECM.