How to Check MOST Bus Condition

If the MOST bus network is broken, it is not possible to diagnose on the System Diagnostic Mode. To check the MOST bus connection, do the ECL test using the multi-information display (MID) in the gauge control module. This test is performed using the diagnostic function of the MOST ECL line. If the MOST ECL circuit is shorted, ECL test will fail.

NOTE: 

• Check the vehicle 12 volt battery condition first .
• If the ECL test results NG, always retry the test 2 or 3 times. Do not judge it as a failure at once.

1. Close all doors and the tailgate.

2. Turn the vehicle to the ON mode.

3. Select the Settings menu on the multi-information display (MID).

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4. While displaying the Settings screen, press and hold the HANG-UP button and then the ENTER button until the MOST bus diagnosis screen is displayed.

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5. This diagnosis checks Pwr (power) and Sig (signal) status about each control unit on the MOST bus network.

NOTE:  The multi-information display (MID) may update to latest information after 35 seconds as maximum delay.

Symbols 

Symbol		Status
Courtesy of HONDA, U.S.A., INC.	GREEN(OK)	The power or MOST signal status is OK at this time.
Courtesy of HONDA, U.S.A., INC.	RED(NG)	The control unit lost the power or cannot receive MOST signal. If the control unit lost the power, both the PWR and SIG symbol indicates it. If the unit is not equipped to the vehicle, or is not connected to the module using the bus, both the PWR and SIG symbol indicates it.

Check for Pwr and Sig indication pattern.

Indication Pattern 

Pwr	Sig	Solution
Courtesy of HONDA, U.S.A., INC.	Courtesy of HONDA, U.S.A., INC.	If all control units indicate this pattern, the power and MOST signal status are OK at this time.
Courtesy of HONDA, U.S.A., INC.	Courtesy of HONDA, U.S.A., INC.	The unit is online but is not receiving signal on the network. Check for MOST TX+/MOST RX+ and MOST TX-/MOST RX- lines between the last control unit in the MOST ring to receive signal and the first with this status. If the wire is OK, substitute each component to a known-good one, and recheck:
Courtesy of HONDA, U.S.A., INC.	Courtesy of HONDA, U.S.A., INC.	Check for ground circuit for the RED symbol control unit. If the wires are OK, the control unit internal power circuit may be faulty. Substitute a known-good control unit, and recheck.
Courtesy of HONDA, U.S.A., INC.	Courtesy of HONDA, U.S.A., INC.	The control unit is either offline or not equipped. NOTE:  If all units indicate double dashes, the MOST ECL line may be shorted. Check for power and ground circuits for the control unit. If the wires are OK, substitute a known-good control unit, and recheck.

NOTE: The units displayed in the multi-information display (MID) are not listed in the correct orientation on the MOST ring. Use the following diagrams to help determine which nodes are receiving and transmitting.

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*: Although this unit may be equipped to the vehicle, it is not available on the MOST bus network.

6. To exit the ECL test, press the HOME button or the BACK button, or turn the vehicle to the OFF (LOCK) mode.