DTC B1223 or DTC indicator M and MODE: A Problem in the Rear Blower Motor Circuit

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.

Clear the DTCs with the HDS.
Turn the ignition switch to LOCK (0) and then back to ON (II).
Do the self-diagnostic function with the HDS (see HOW TO USE THE SELF-DIAGNOSTIC FUNCTION WITH THE HDS ) or the climate control unit (see HOW TO USE THE SELF-DIAGNOSTIC FUNCTION WITHOUT THE HDS ).
Check for DTCs.
Is DTC B1223 or M and MODE indicated?

YES -Go to step 5.

NO -Intermittent failure, check for loose wires or poor connections in the rear blower motor circuit.
Turn the ignition switch to LOCK (0).
Check the No. 2 (RR BLOWER) (30 A) fuse in the main under-hood fuse box, and the No. 30 (10 A) fuse in the under-dash fuse/relay box.
Are the fuses OK?

YES -Go to step 7.

NO -Replace the fuse(s), and recheck. If fuse(s) blow again, check for a short in the No. 2 (RR BLOWER) (30 A) and No. 30 (10 A) fuse(s) circuit.
Connect rear blower motor 2P connector terminal No. 2 to body ground with a jumper wire.

Fig 1: Connecting Rear Blower Motor 2P Connector Terminal No. 2 To Body Ground With Jumper Wire
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Turn the ignition switch to ON (II).
Does the rear blower motor run at high speed?

YES -Go to step 9.

NO -Go to step 24.
Turn the ignition switch to LOCK (0).
Disconnect the jumper wire.
Disconnect the rear power transistor 4P connector.
Check for continuity between rear power transistor 4P connector terminal No. 2 and body ground.

Fig 2: Checking For Continuity Between Rear Power Transistor 4P Connector Terminal No. 2 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 13.

NO -Check for an open in the wire between the rear power transistor and body ground. If the wire is OK, check for poor ground at G503 (see CONNECTOR TO FUSE/RELAY BOX INDEX ).
Connect rear power transistor 4P connector terminals No. 2 and No. 4 with a jumper wire.

Fig 3: Connecting Rear Power Transistor 4P Connector Terminals No. 2 And No. 4 With Jumper Wire
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Turn the ignition switch to ON (II).
Does the rear blower motor run at high speed?

YES -Go to step 15.

NO -Repair an open in the ORN wire between the rear power transistor and the rear blower motor.
Turn the ignition switch to LOCK (0).
Disconnect the jumper wire.
Disconnect climate control unit connector B (14P).
Check for continuity between body ground and climate control unit connector B (14P) terminals No. 13 and No. 14 individually.

Fig 4: Checking For Continuity Between Body Ground And Climate Control Unit Connector B (14P) Terminals No. 13 And No. 14
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair a short to body ground in the wire(s) between the climate control unit and the rear power transistor.

NO -Go to step 19.
Check for continuity between the following terminals of climate control unit connector B (14P) and the rear power transistor 4P connector.
14P:

No. 13

No. 14

4P:

No. 3

No. 1

Fig 5: Checking For Continuity Between Terminals Of Climate Control Unit Connector B (14P) And Rear Power Transistor 4P Connector
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 20.

NO -Repair an open in the wire(s) between the climate control unit and the rear power transistor.
Turn the ignition switch to ON (II).
Measure the voltage between body ground and climate control unit connector B (14P) terminals No. 13 and No. 14 individually.

Fig 6: Measuring Voltage Between Body Ground And Climate Control Unit Connector B (14P) Terminals No. 13 And No. 14
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there any voltage?

YES -Repair a short to power in the wire(s).

NO -Go to step 22.
Reconnect climate control unit connector B (14P).
Test the rear power transistor (see REAR POWER TRANSISTOR TEST ).
Is the rear power transistor OK?

YES -Check for loose wires or poor connections at climate control unit connector B (14P) and at the rear power transistor 4P connector. If the connections are good, substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit (see CLIMATE CONTROL UNIT REMOVAL/INSTALLATION ).

NO -Replace the rear power transistor.
Disconnect the jumper wire.
Disconnect the rear blower motor 2P connector.
Measure the voltage between rear blower motor 2P connector terminal No. 1 and body ground.

Fig 7: Measuring Voltage Between Rear Blower Motor 2P Connector Terminal No. 1 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?

YES -Replace the rear blower motor (see REAR BLOWER MOTOR REPLACEMENT ).

NO -Go to step 27.
Turn the ignition switch to LOCK (0).
Remove the rear blower motor relay from the dashboard wire harness, and test it (see POWER RELAY TEST ).
Is the relay OK?

YES -Go to step 29.

NO -Replace the rear blower motor relay.
Measure the voltage between rear blower motor relay 4P socket terminal No. 1 and body ground.

Fig 8: Measuring Voltage Between Rear Blower Motor Relay 4P Socket Terminal No. 1 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?

YES -Go to step 30.

NO -Repair an open in the wire between the No. 2 (RR BLOWER) (30 A) in the main under-hood fuse box and the rear blower motor relay.
Turn the ignition switch to ON (II).
Measure the voltage between rear blower motor relay 4P socket terminal No. 4 and body ground.

Fig 9: Measuring Voltage Between Rear Blower Motor Relay 4P Socket Terminal No. 4 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?

YES -Go to step 32.

NO -Repair an open in the wire between the No. 30 (10 A) fuse in the under-dash fuse/relay box and the rear blower motor relay.
Turn the ignition switch to LOCK (0).
Check for continuity between rear blower motor relay 4P socket terminal No. 3 and body ground.

Fig 10: Checking For Continuity Between Rear Blower Motor Relay 4P Socket Terminal No. 3 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair an open in the GRY wire between the rear blower motor relay and the blower motor.

NO -Check for an open in the wire between the rear blower motor relay and body ground. If the wire is OK, check for poor ground at G304 (see CONNECTOR TO FUSE/RELAY BOX INDEX ).