Honda Multiplexing Board Worksheet

Honda Multiplexing Board Worksheet

This multiplex system was used for body controlled functions on 1996 to 2002 Honda accord and 1996 onward prelude. It utilises three nodes ( control units ) drivers door, drivers side and passenger side. The testing procedure is divided in to three sections
Communication lines and  nodes from mode 1, inputs from mode 2. If the system passes these test from mode 1 and 2, but is still faulty the problem is likely to be an output.

1: Using the wiring diagram identify the plugs/ pins and wire colours for the communication lines between the nodes.
Multiplex control unit to multiplex control unit drive A15 to A2 Brown wire. Multiplex control unit drives to multiplex control unit to passanger B1 to B9 Pink wire.

2: Using the wiring diagram identify the plugs/ pins and wire colours for the Earths and voltage supply lines between the nodes.
Multiplex control unit door is A12 to G401, multiplex control unit drivers is B11 to G501 & A14 to G401 , multiplex control unit passanger is B22 to G501 & A8 to G461. (G501 , G401,Black wire)

3: Ask your instructor to create a fault in the unit
Describe in detail how this fault is affecting the normal operation of this system
I setp up to mode2, everything works well, except the driver side rear door light switch.

4: Using the wiring diagram analyze the fault and describe in detail what may be causing this fault
I think the problem should be the right ( left ) rear door switch disconnection from multiplex control unit door switch or something wrong with the ground connection.

5: After reading the manual put the system in to test mode 1. Note the codes ( if any ) and possible faults that the system gives you
There is no codes come out

6: Do the codes concur with what you thought the problem might be from question 4, explain
Because there is no codes and beep, so I can not check my thought from question 4 is right or wrong

7: Go to step 5, can you conduct this test? Why/ Why not.
Yes, all the communction lines were good

8: Conduct the tests in step 6, what is your results and conclisions.
Door to drive's, Brown wire was good , it was 5.2V as the spec 3.5-9.5V
Drive's to passanger's, Pink wire also good, like 5.2V, it as the spec 3.0-10.0V

9: Put the system in to diagnostic mode 2, conduct the input test and note the results.
When I put to mode 2, all works well with beep, but the drive side rear door light switch doesn't work and without beep.

10: Explain your results and conclusions, Does it concur with your diagnosis from question 4?
The switch should be faulty as the rest work, but drive side rear didn't. All the communcation lines in good contion.