DTC B1000: Communication Bus Line Error

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: If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A

Clear the DTCs with the HDS.
Turn the ignition switch to LOCK (0) and then back to ON (II).
Wait for at least 6 seconds.
Check for DTCs with the HDS.
Is DTC B1000 indicated?

YES -Go to step 5.

NO -Intermittent failure, the communication bus line is OK at this time. Check for loose or poor connections, or worn/shorted wires. If the connections are good, check the battery condition BATTERY TEST ) and the charging system.
Check for DTCs with the HDS.
Are DTCs B1000, B1005, B1007, B1011, 1012, B1013, B1015 and B1032 all indicated?

YES -Go to step 6.

NO -Faulty MICU; replace the under-dash fuse/relay box.
Turn the ignition switch to LOCK (0).

Disconnect the appropriate connector for each control unit in the table one at a time. Clear the DTC, then recheck for DTCs after each unit is disconnected.

NOTE: Leave the control unit connector disconnected after checking for DTCs, before moving on to the next control unit.

Control unit

Connector

Relay control module

Under-hood fuse/relay box connector E (14P)

Gauge control module

Connector A (12P)

Immobilizer-keyless control unit

7P connector

Combination switch control unit

8P connector

Driver's MPCS unit

Connector A (40P)

Climate control unit

Connector A (40P)

Audio unit

Connector C (24P)

Audio-navigation unit

Connector F (20P)

HandsFreeLink control unit

28P connector

Power seat control unit

Connector A (40P)

Power tailgate control unit

Connector C(14P)

AcuraLink control unit (XM receiver)

connector A (32P)

BSI control unit

16P connector

Rear MICU⁽⁾

Rear fuse/relay box connector B (34P)

⁽¹⁾	Disconnect this one last

Is DTC B1000 indicated with each individual unit disconnected?

YES -Go to step 8.

NO -Replace the control unit that was disconnected when B1000 did not reset.

Disconnect rear fuse/relay box connector C (42P).

Check for continuity between each of the control unit connector terminals listed in the table and body ground.

Control unit	Connector terminal
Power seat control unit	A40
Power tailgate control unit	C7
AcuraLink control unit (XM receiver)	No. 10
BSI control unit	No. 5

Is there continuity?

YES -Repair a short to ground in the wire between the rear fuse/relay box and the affected control unit.

NO -Go to step 10.

Measure the voltage between each of the rear fuse/relay box connector terminals listed in the table and body ground.

Control unit	Connector terminal
Power seat control unit	A40
Power tailgate control unit	C7
AcuraLink control unit (XM receiver)	No. 10
BSI control unit	No. 5

Is there less than 0.2 V?

YES -Go to step 11.

NO -Repair a short to power in the wire between the rear fuse/relay box and the affected control unit.

Check for continuity between under-dash fuse/relay box connector N (45P) terminal No. 22 and body ground.

Fig 1: Checking For Continuity Between Connector N (45P) Terminal No. 22 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair a short to ground in the wire.

NO -Go to step 12.
Turn the ignition switch to ON (II).
Measure the voltage between under-dash fuse/relay box connector N (45P) terminal No. 22 and body ground.

Fig 2: Measuring Voltage Between Connector N (45P) Terminal No. 22 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?

YES -Repair a short to power in the wire.

NO -Faulty MICU, replace the under-dash fuse/relay box.