Mode 1 Test

NOTE: Check for ECM/PCM DTC(s). Troubleshoot and repair the cause for the DTC(s) first.

Remove the driver's dashboard lower cover (see DRIVER'S DASHBOARD LOWER COVER REMOVAL/INSTALLATION ).
Check the No. 9 (10 A) fuse in the underhood fuse/relay box and the No. 10 (7.5 A) fuse in the under-dash fuse/relay box.
Are the fuses OK?
1. YES - Go to step 3.
2. NO - Find and repair the cause of the blown fuse.
Turn the ignition switch ON (II).
If the driver's seat belt is unbuckled, the seat belt reminder will beep 6 times.
Set the ceiling light to the middle position and close all the doors.
Connect the special tool (A) to the multiplex inspection connector (B).

Fig 1: Connecting Special Tool To Multiplex Inspection Connector
Courtesy of AMERICAN HONDA MOTOR CO., INC.

MODE 1: Ignition key light and ceiling light

Fig 2: Identifying Ignition Key Light And Ceiling Light
Courtesy of AMERICAN HONDA MOTOR CO., INC.
After about 5 seconds, the ignition key light and ceiling light should come on for 2 seconds, go out, then blink on for 0.2 second to show the system is now in Mode 1.
Did the ignition key light and ceiling light indicate mode 1?
1. YES - Go to step 8 .
2. NO - Go to step 7.
Check for continuity between the No. 4 terminal of the under-dash fuse/relay box connector J and body ground.
Is there continuity?
1. YES - Replace the under-dash fuse/relay box.
2. NO - Repair the open in the wire. If the wire is OK, repair G301.
If there are any DTCs present, the ignition key light and ceiling light will blink to indicate the DTC(s). If more than one DTC is present, the DTCs will be displayed in ascending order. If there are no DTCs, the ignition key light and ceiling light will not blink again after the Mode 1 indication.
Are there any DTCs?
1. YES - Go to step 9.
2. NO - Go to Mode 2 Test (see MODE 2 TEST ).

Troubleshoot the DTC(s) in the order indicated using the following charts.

If a faulty control unit is suspected, substitute it with a known-good part and recheck for DTCs.

If the DTC(s) is still present, go to the next step listed for the DTC.
If the DTC(s) is no longer present, replace the original part.

Individual DTCs

INDIVIDUAL DTCS

Multiplex DTC

Probable Cause

The multiplex control unit cannot receive signals from the gauge assembly.

Faulty power or ground to the gauge assembly
Faulty gauge assembly
Faulty under-dash fuse/relay box

The multiplex control unit cannot receive signals from the ECM/PCM

Faulty power or ground to the ECM/PCM
Faulty ECM/PCM ⁽¹⁾
Faulty under-dash fuse/relay box

Internal failure of the multiplex control unit

Faulty under-dash fuse/relay box

The gauge assembly cannot receive signals from the ECM/PCM

Faulty power or ground to the ECM/PCM
Faulty gauge assembly

The ECM/PCM cannot receive signals from the multiplex control unit and the gauge assembly

Faulty power or ground to the ECM/PCM
Faulty gauge assembly

⁽¹⁾	Before replacing a faulty ECM/PCM, make sure it has the latest software revision. Update if necessary before swapping or replacing.

Multiple DTCs

MULTIPLE DTCS

Multiplex DTCs	Probable Cause
1,2 and 3 & ECM DTC P0600 Simultaneously	Short to ground on one of the communication wires. Short to ground on the YEL wire between the ECM/PCM terminal E24 [E13] and the under-dash fuse/relay box terminal E10 Short to ground on the WHT/GRN wire between the gauge assembly terminal B13 [B11]and under-dash fuse/relay box terminal K10
1 and 6 Simultaneously	Open in the communication wire
1 and 6 Simultaneously	Open in WHT/GRN wire between the under-dash fuse/relay box terminal K10 and the gauge assembly terminal B13 [B11]
2 and 5 Simultaneously	Open in the communication wire
2 and 5 Simultaneously	Open in the YEL wire between the under-dash fuse/relay box terminal E10 and ECM/PCM terminal E10 and ECM/PCM terminal E24 [E13]

[ ]: '05-06 models