DTC B1626: Ignition Switch Control Unit No Response

Clear the DTCs with the HDS.
Select the MODE MENU from the HDS.
Do the SELF CHECK.
Check for DTCs with the HDS.
Is DTC B1626 indicated?

YES - Go to step 5.

NO - Intermittent failure, the ignition switch control unit is OK at this time. Check for loose or poor connections at the ignition switch control unit connector.
Register the ignition switch control unit with the HDS.
Turn the ignition switch OFF, and then back ON (II).
Repeat step 6 nine times.
Check for DTCs with the HDS.
Is DTC B1626 indicated?

YES - Go to step 9.

NO - Intermittent failure, the ignition switch control unit is OK at this time. Check for loose or poor connections at the ignition switch control unit connector.
Turn the ignition switch OFF.
Disconnect the ignition switch control unit 10P connector.
Turn the ignition switch ON (II).
Measure the voltage between the ignition switch control unit 10P connector terminal No. 9 and body ground.

Fig 1: Measuring Voltage Between Ignition Switch Control Unit 10P Connector Terminal No. 9 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?

YES - Go to step 13.

NO - Check the No. 7 (10A) fuse in the driver's under-dash fuse/relay box. If the fuse is OK, check for an open in the wire between the driver's under-dash fuse/relay box and the ignition switch control unit.
Turn the ignition switch OFF.
Check for continuity between ignition switch control unit 10P connector terminal No. 6 and body ground.

Fig 2: Checking Continuity Between Ignition Switch Control Unit 10P Connector Terminal No. 6 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES - Go to step 15.

NO - Repair an open in the wire or a poor ground (G501).
Disconnect keyless access control unit connector A (31P).

Check for continuity between the following ignition switch control unit 10P connector terminals and keyless access control unit connector A (31P) terminals:

CONTINUITY CHART

IGNITION SWITCH CONTROL UNIT	KEYLESS ACCESS CONTROL UNIT CONNECTOR A (31P)
No. 3	No. 13
No. 4	No. 26
No. 5	No. 8
No. 7	No. 4
No. 8	No. 3

Fig 3: Checking Continuity Between Ignition Switch Control Unit 10P Connector Terminals And Keyless Access Control Unit Connector A (31P) Terminals (1 Of 2)

Courtesy of AMERICAN HONDA MOTOR CO., INC.

Fig 4: Checking Continuity Between Ignition Switch Control Unit 10P Connector Terminals And Keyless Access Control Unit Connector A (31P) Terminals (2 Of 2)

Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES - Go to step 17.

NO - Repair an open in the wire.

Check for continuity between body ground and ignition switch control unit 10P connector terminals No. 3, No. 4, No. 5, No. 7, and No. 8 individually.

Fig 5: Checking Continuity Between Body Ground And Ignition Switch Control Unit 10P Connector Terminals No. 3, 4, 5, 7 And 8
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES - Repair a short to ground in the wire.

NO - Go to step 18.
Reconnect keyless access control unit connector A (31P).
Connect the voltmeter between ignition switch control unit 10P connector terminal No. 5 and body ground.

Fig 6: Checking Voltage Between Ignition Switch Control Unit 10P Connector Terminal No. 5 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Turn the ignition switch ON (II).
Select the FUNCTION TEST from the HDS MODE MENU, and do the IGNTRX LINE DRIVING.
Does the voltage change from about 12V to 0V?

YES - Go to step 22.

NO - Replace the keyless access control unit.
Connect the voltmeter between ignition switch control unit 10P connector terminal No. 4 and body ground.

Fig 7: Checking Voltage Between Ignition Switch Control Unit 10P Connector Terminal No. 4 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Select the FUNCTION TEST MENU from the HDS, and do the IGNCONT LINE DRIVING.
Does the voltage change from 0 to 5 V?

YES - Replace the ignition switch control unit.

NO - Replace the keyless access control unit.