DTC B1627: RF1 Unit Disconnected; DTC B1640: RF1 Unit Transmitter/Receiver Circuit Malfunction

NOTE: If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A (see TROUBLESHOOTING - B-CAN SYSTEM DIAGNOSIS TEST MODE A ).

Clear the DTCs with the HDS.
Turn the ignition switch to LOCK (0) and then back to ON (II).
Select MODE MENU from the HDS, then enter SELF CHECK.
Do the SELF CHECK.
Check for DTCs with the HDS.
Is DTC B1627 and/or B1640 indicated?

YES -Go to step 6.

NO -Go to step 12.
Turn the ignition switch to LOCK (0).
Disconnect the RF unit 1 6P connector.
Disconnect keyless access control unit connector C (17P).

Check for continuity between following RF unit 1 6P connector terminals and keyless access control unit connector C (17P) terminals.

CONTINUITY SPECIFICATIONS

RF UNIT 16P CONNECTOR	KEYLESS ACCESS CONTROL UNIT CONNECTOR C (17P)
No. 1	No. 1
No. 2	No. 2
No. 3	No. 14
No. 4	No. 13
No. 5	No. 7
No. 6	No. 8

Fig 1: Checking Continuity Between RF Unit 1 6P Connector Terminals

Courtesy of AMERICAN HONDA MOTOR CO., INC.

Fig 2: Checking Continuity Between Keyless Access Control Unit Connector C (17P) Terminals

Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 10.

NO -Repair an open or high resistance in the wire.

Check for continuity between body ground and RF unit 1 6P connector terminals No. 1, No. 2, No. 3, No. 4, No. 5, and No. 6 individually.

Fig 3: Checking Continuity Between Body Ground And Rf Unit 1 6P Connector Terminals No. 1, No. 2, No. 3, No. 4, No. 5 And No. 6
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair a short to ground in the wire.

NO -Go to step 11.
Reconnect the RF unit 1 6P connector and keyless access control unit connector C (17P).
Connect the voltmeter between RF unit 1 6P connector terminal No. 5 and body ground.

Fig 4: Connecting Voltmeter Between RF Unit 1 6P Connector Terminal No. 5 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Select FUNCTION TEST from the HDS, and do RF1 RXVCC DRIVING.
Does the voltage change from 0 to about 5 V?

YES -Go to step 14.

NO -Replace the keyless access control unit (see KEYLESS ACCESS CONTROL UNIT INPUT TEST/REPLACEMENT ).
Connect the voltmeter between RF unit 1 6P connector terminal No. 6 and body ground.

Fig 5: Connecting Voltmeter Between Rf Unit 1 6P Connector Terminal No. 6 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Select FUNCTION TEST from the HDS, and do RF1 TXVCC DRIVING.
Does the voltage change from 0 to about 5 V?

YES -Go to step 16.

NO -Replace the keyless access control unit (see KEYLESS ACCESS CONTROL UNIT INPUT TEST/REPLACEMENT ).
Connect the voltmeter between RF unit 6P connector terminal No. 3 and body ground.

Fig 6: Connecting Voltmeter Between RF Unit 6P Connector Terminal No. 3 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Select FUNCTION TEST from the HDS, and do RF1 TXDDC OUTPUT.
Does the voltage change from 0 to about 5 V?

YES -Replace the RF unit 1 (see RF UNIT 1 REPLACEMENT ).

NO -Replace the keyless access control unit (see KEYLESS ACCESS CONTROL UNIT INPUT TEST/REPLACEMENT ).