Acura TSX / Honda Accord CL. Manual - part 144

Since the door lock switch message was received by all the ECUs expecting to receive a signal, the 
communication circuit between those units is OK. There are multiple signal sent and received by each ECU 
during this time to insure that the communication circuit is intact. 

Failed Circuit 

1. Ignition switch is turned ON.  

2. The door multiplex control unit transmits a door switch signal.  

3. The multiplex integrated control unit (MICU), relay control module and gauge control module expect to 

receive the door lock switch signal, but since there is a break in the communication circuits, it is not 
received.  

4. Each ECU that expects to receive the door lock switch signal from the door multiplex control unit will 

transmit DTCs for the signal that it did not receive.  

Fig. 6: Example Of Failed Circuit 

Since there is a break in the communication circuit, the door lock switch signal could not be received by the 
gauge control module, multiplex integrated control unit (MICU) or the relay control module. Each of these units 
will set "loss of communication" error codes for the signal(s) they did not receive. There may be multiple 
communication DTCs if the unit that has become disconnected from the network would normally transmit 
multiple messages during the communication line test. For example, the door multiplex control unit sends 
keyless panic signal and door lock switch signal during the communication circuit test. 

DIAGNOSTIC TROUBLE CODES 

There are three DTC types used by the CAN networks.

 

2004 Acura TSX 

2004 ACCESSORIES & EQUIPMENT Multiplex Integrated Control System - TSX

  

 

Fig. 7: CAN Networks Diagnostic Trouble Code Type Table 

TROUBLESHOOTING THE CAN CIRCUIT RELATED PROBLEMS 

Using the HDS (Preferred method) 

1. Go to B-CAN System Diagnosis Test Mode A to check for "Connected units" and DTCs (see B-CAN 

SYSTEM DIAGNOSIS TEST MODE A ).  

2. If no DTCs are retrieved, go to B-CAN System Diagnosis Test Mode C or D.  

Without the HDS (Should be used only if HDS is unavailable) 

1. Check for communication circuit problems using B-CAN System Diagnosis Test Mode 1 (see B-CAN 

SYSTEM DIAGNOSIS TEST MODE A ).  

2. Check for DTCs while in Mode 1 (see B-CAN SYSTEM DIAGNOSIS TEST MODE A ).  

3. Sort, and then troubleshoot the DTCs in the order below. Refer to the DTC troubleshooting Index for 

DTC descriptions. 

1st: Internal error and voltage failure DTCs  

2nd: Loss of communication DTCs  

3rd: Signal error DTCs  

4. If no DTCs are retrieved, use B-CAN System Diagnosis Test Mode 2 to check all inputs related to failure 

(see B-CAN SYSTEM DIAGNOSIS TEST MODE A ).  

Loss of Communication DTC cross-reference chart 

When an ECU is unable to communicate with the other ECUs on the circuit, the other units will set loss of 
communication DTCs. Use this chart to find the control unit that is not communicating.  

1. Find the Transmitting Unit that is in the same row as all of the loss of communication DTCs retrieved.  

2. Perform the input test for the transmitting unit. 

 

2004 Acura TSX 

2004 ACCESSORIES & EQUIPMENT Multiplex Integrated Control System - TSX

  

 

Fig. 8: Loss Of Communication DTC Cross-Reference Chart 

B-CAN SYSTEM SWITCH DEVICE INDEX 

Fig. 9: Combination Switch Control Unit Table 

Fig. 10: Relay Control Module Table 

 

2004 Acura TSX 

2004 ACCESSORIES & EQUIPMENT Multiplex Integrated Control System - TSX

  

 

Fig. 11: Door Multiplex Control Unit Table 

Fig. 12: Multiplex Integrated Control Unit Table 

Fig. 13: Gauge Control Module Table 

 

2004 Acura TSX 

2004 ACCESSORIES & EQUIPMENT Multiplex Integrated Control System - TSX