Display does not dim or brighten with dimmer (without navigation)

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:

Check the vehicle battery condition first (see BATTERY TEST ).
Check the connectors for poor connections or loose terminals.

Turn the ignition switch to ON (II).
Turn the headlight switch to the parking or headlight on position.
Check the front climate control unit display.
Does the climate control illumination change with dimmer?

YES -Go to step 4.

NO -Go to climate control unit troubleshooting (see CLIMATE CONTROL UNIT POWER AND GROUND CIRCUIT TROUBLESHOOTING ).
Check the No. 7 (10 A) fuse and the No. 32 (10 A) fuse in the under-dash fuse/relay box.
Are the fuses OK?

YES -Go to step 5.

NO -Replace the fuse(s), and recheck.
Remove the audio unit (see AUDIO UNIT REMOVAL/INSTALLATION ). Check that the audio unit and climate control unit connectors are properly connected.
Are they connected properly?

YES -Go to step 6.

NO -Repair poor connections and reconnect the connector, and recheck.
Turn the ignition switch to LOCK (0).
Disconnect audio unit connector C (24P) and climate control unit connector B (14P).
Check for continuity between audio unit connector C (24P) terminal No. 24 and climate control unit connector B (14P) terminal No. 8.

Fig 1: Checking Continuity Between Connector C (24P) Terminal No. 24 And Connector B (14P) Terminal No. 8
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 9.

NO -Repair an open in the wire between the audio unit and the climate control unit.
Check for continuity between audio unit connector C (24P) terminal No. 24 and body ground.

Fig 2: Checking Continuity Between Connector C (24P) Terminal No. 24 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair a short to body ground in the wire between the audio unit and the climate control unit.

NO -Go to step 10.
Measure the voltage between climate control unit connector A (40P) terminal No. 1 and body ground.

Fig 3: Measuring Voltage Between Connector A (40P) Terminal No. 1 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?

YES -Go to step 11.

NO -Repair an open in the wire between the No. 7 (10 A) fuse in the under-dash fuse/relay box and the climate control unit.
Turn the ignition switch to ON (II).
Measure the voltage between climate control unit connector A (40P) terminal No. 25 and body ground.

Fig 4: Measuring Voltage Between Connector A (40P) Terminal No. 25 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?

YES -Go to step 13.

NO -Repair an open in the wire between the No. 32 (10 A) fuse in the under-dash fuse/relay box and the climate control unit.
Measure the voltage between climate control unit connector A (40P) terminal No. 37 and body ground.

Fig 5: Measuring Voltage Between Connector A (40P) Terminal No. 37 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there less than 0.2 V?

YES -Substitute a known-good climate control unit (see FRONT EVAPORATOR TEMPERATURE SENSOR REPLACEMENT ), and recheck. If the symptom/indication goes away, replace the original climate control unit (see FRONT EVAPORATOR TEMPERATURE SENSOR REPLACEMENT ). If the symptom is still present, substitute a known-good audio unit (see AUDIO UNIT REMOVAL/INSTALLATION ), and recheck. If the symptom/indication goes away, replace the original audio unit (see AUDIO UNIT REMOVAL/INSTALLATION ).

NO -Repair an open or high resistance in the wire between climate control unit connector A (40P) terminal No. 37 and body ground (G506) (see CONNECTOR TO FUSE/RELAY BOX INDEX ).