DTC P1519: IAC Valve Circuit Malfunction

Reset the PCM (see HOW TO RESET THE PCM ).
Turn the ignition switch ON (II).
Is DTC P1519 indicated?
1. YES -Go to step 3.
2. NO -Intermittent failure, system is OK at this time. Check for poor connections or loose terminals at the IAC valve and at the PCM.
Turn the ignition switch OFF.
Disconnect the IAC valve 3P connector.
Turn the ignition switch ON (II).
Measure voltage between IAC valve 3P connector terminal No. 2 and body ground.

Fig 1: Measuring Voltage Between IAC Valve 3P Connector Terminal No. 2 & Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?
1. YES -Go to step 7.
2. NO -Repair open in the wire between the IAC valve and the PGM-FI main relay.
Turn the ignition switch OFF.
Check for continuity between body ground and IAC valve 3P connector terminal No. 1.

Fig 2: Checking For Continuity Between Body Ground & IAC Valve 3P Connector Terminal No. 1
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?
1. YES -Go to step 9.
2. NO -Repair open in the wire between the IAC valve and G101.
Disconnect PCM connector B (125P).
Check for continuity between body ground and PCM connector terminal B23.

Fig 3: Checking For Continuity Between Body Ground & PCM Connector Terminal B23
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?
1. YES -Repair short in the wire between the IAC valve and the PCM (B23).
2. NO -Go to step 11.
Connect IAC valve 3P connector terminal No. 3 to body ground with a jumper wire.

Fig 4: Connecting IAC Valve 3P Connector Terminal No. 3 To Body Ground With A Jumper Wire
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Check for continuity between PCM connector terminal B23 and body ground.

Fig 5: Checking For Continuity Between PCM Connector Terminal B23 & Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?
1. YES -Go to step 13.
2. NO -Repair open in the wire between the IAC valve and the PCM (B23).
Remove the jumper wire from the IAC valve 3P connector, then reconnect the IAC valve 3P connector.
Turn the ignition switch ON (II).
Measure voltage between body ground and PCM connector terminal B23.

Fig 6: Measuring Voltage Between Body Ground & PCM Connector Terminal B23
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?
1. YES -Substitute a known-good PCM and recheck (see HOW TO SUBSTITUTE THE PCM FOR TESTING ). If the symptom/indication goes away, replace the original PCM.
2. NO -Replace the IAC valve.