Front Wiper Operates by Itself in Fine Weather

CHECK CONDITIONS OF WINDSHIELD (RAIN SENSOR DETECTION AREA)
Check rain sensor detection area of windshield for dirt such as greases.

OK or NG
1. OK: GO TO 2.
2. NG: Clean rain sensor detection area of windshield fully.
CHECK RAIN SENSOR OUTPUT SIGNAL
With CONSULT-II
1. Select "IVMS" on CONSULT-II. And select "WIPER" on "SELECT TEST ITEM" screen.
2. Select "DATA MONITOR" on "SELECT DIAG MODE" screen.
3. Make sure that "RAIN SENSOR" of "DATA MONITOR" is 87 % with no water drops in sensor detection area.
  
  Fig 1: SELECT DIAG MODE - CONSULT II Display
  Courtesy of NISSAN MOTOR CO., U.S.A.
Without CONSULT-II

With no water drops in sensor detection area, check voltage waveform between BCM harness connector R4 terminal 134 (B/R) and ground when wiper stops.
1. 134 (B/R) - Ground: Refer to "TERMINALS AND REFERENCE VALUES FOR BCM ".
OK or NG
1. OK: Replace BCM.
2. NG: GO TO 3.
CHECK RAIN SENSOR OUTPUT SIGNAL CIRCUIT
1. Disconnect BCM connector.
2. Check continuity between rain sensor harness connector R20 terminal 2 (B/R) and BCM harness connector R4 terminal 134 (B/R).
  1. 2 (B/R) - 134 (B/R): Continuity should exist.
3. Check continuity between rain sensor harness connector R20 terminal 2 (B/R) and ground.
  1. 2 (B/R) - Ground: Continuity should not exist.
  Fig 2: Checking Rain Sensor Output Signal Circuit
  Courtesy of NISSAN MOTOR CO., U.S.A.
OK or NG
1. OK: GO TO 4.
2. NG: Check harness for open or short between rain sensor and BCM.
CHECK RAIN SENSOR POWER SUPPLY
1. Turn ignition switch OFF.
2. Disconnect rain sensor connector.
3. Turn ignition switch ON.
4. Check voltage between rain sensor harness connector R20 terminal 1 (B/OR) and ground.
  1. 1 (B/OR) - Ground: Battery voltage
OK or NG
1. OK: GO TO 2.
2. NG: Check harness for open or short between rain sensor and fuse.
  
  Fig 3: Checking Voltage Between Rain Sensor Harness Connector R20 Terminal 1 (B/OR) And Ground
  Courtesy of NISSAN MOTOR CO., U.S.A.
CHECK RAIN SENSOR GROUND CIRCUIT
1. Turn ignition switch OFF.
2. Check continuity between rain sensor harness connector R20 terminal 3 (B) and ground.
  1. 3 (B) - Ground: Continuity should exist.
OK or NG
1. OK: Replace rain sensor.
2. NG: Check harness ground circuit.
Fig 4: Checking Continuity Between Rain Sensor Harness Connector R20 Terminal 3 (B) And Ground
Courtesy of NISSAN MOTOR CO., U.S.A.