DTC 81-1: Left Search Coil Sensor Malfunction

WARNING: This page is about a different car, the 2013 Acura MDX, 2012 Acura MDX, 2011 Acura MDX, and 2010 Acura MDX. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Before you troubleshoot, review the general troubleshooting information (see GENERAL TROUBLESHOOTING INFORMATION ).

Turn the ignition switch to LOCK(0).
Disconnect SH-AWD control unit connector A (20P).
Check for continuity between SH-AWD control unit connector terminals A1 and A11.

Fig 1: Checking Continuity Between SH-AWD Control Unit Connector Terminals A1 And A11
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 4.

NO -Go to step 7.
Check the REAR DIFFERENTIAL FLUID TEMPERATURE in the DATA LIST is above 68°F (20°C) with the HDS before proceeding to the next step. If the temperature is below 68°F (20°C), drive the vehicle to warm up the rear differential until the fluid temperature becomes above 68°F (20°C).
Measure the resistance between SH-AWD control unit connector terminals A1 and A11.

Fig 2: Measuring Resistance Between SH-AWD Control Unit Connector Terminals A1 And A11
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there 2.0 O or more?

YES -Go to step 6.

NO -Go to step 9.
Check for continuity between SH-AWD control unit connector terminal A1 and body ground.

Fig 3: Checking Continuity Between SH-AWD Control Unit Connector Terminal A1 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair a short in the wire between SH-AWD control unit connector terminal A1 and body ground.

NO -Check for loose connector terminals at the SH-AWD control unit and repair if necessary. If the connections are OK, update the SH-AWD control unit if it does not have the latest software (see SH-AWD® CONTROL UNIT UPDATE ), or substitute a known-good SH-AWD control unit (see SH-AWD® CONTROL UNIT REPLACEMENT ), and recheck. If the symptom/indication goes away with the updated SH-AWD control unit, troubleshooting is complete. If the symptom/indication goes away with a known-good SH-AWD control unit, replace the original SH-AWD control unit (see SH-AWD® CONTROL UNIT REPLACEMENT ).

NOTE: If a new SH-AWD control unit was used in place of the known-good control unit and the new control unit will not initialize, replace the rear differential left side case.
Disconnect the left solenoid 4P connector.
Connect SH-AWD control unit connector terminals A1 and A11 with a jumper wire. Disconnect the left solenoid 4P connector, then check for continuity between left solenoid 4P connector terminals No. 3 and No. 4.

Fig 4: Connecting SH-AWD Control Unit Connector Terminals A1 And A11 With Jumper Wire
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Fig 5: Checking Continuity Between Left Solenoid 4P Connector Terminals No. 3 And No. 4
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Replace the rear differential left side case (see SIDE CASE REPLACEMENT ).

NO -Repair an open in the wire between left solenoid 4P connector terminals No. 3 and No. 4.
Disconnect the left solenoid 4P connector.
Check for continuity between left solenoid 4P connector terminals No. 3 and No. 4.

Fig 6: Checking Continuity Between Left Solenoid 4P Connector Terminals No. 3 And No. 4
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair a short in the wires between SH-AWD control unit connector A and the left search coil sensor connector.

NO -Replace the rear differential left side case (see SIDE CASE REPLACEMENT ).