Vehicle Speed Signal Inspection

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2005 Infiniti FX45, 2005 Infiniti FX35, 2004 Infiniti FX45, 2004 Infiniti FX35, and 2003 Infiniti FX45. However, it is still accessible from the selected car via links, so may be relevant.

Symptom: Indication is irregular for the speedometer and odo/trip meter.

CHECK ABS ACTUATOR AND ELECTRIC UNIT (CONTROL UNIT) SELF-DIAGNOSIS
Preform the ABS actuator and electric unit (control unit) self-diagnosis. Refer to "CONSULT-II FUNCTIONS ".

Self-diagnostic results content
1. No malfunction detected:GO TO 2.
2. Malfunction detected:Check applicable parts, and repair or replace corresponding parts.
CHECK UNIFIED METER AND A/C AMP. OUTPUT SIGNAL
1. Start engine and drive vehicle at approximately 40 km/h (25 MPH).
2. Check voltage signal between unified meter and A/C amp. harness connector M56 terminal 26 (R/G) and ground.
  NOTE: Maximum voltage may be 5 V due to specifications (connected units).
  1. 26 (R/G) - Ground:
Fig 1: Voltage Signal Waveform
Courtesy of NISSAN MOTOR CO., U.S.A.

Fig 2: Checking Voltage Signal Between Terminal 26 And Ground
Courtesy of NISSAN MOTOR CO., U.S.A.

OK or NG
1. OK: GO TO 3.
2. NG :
  - If monitor indicates "0 V" constantly, repair or replace malfunctioning parts after checking each unit inputting vehicle speed signal (8 pulse), harness and connector between each unit and unified meter and A/C amp.
  - If monitor indicates "5 V" or "12 V" constantly, replace unified meter and A/C amp. Refer to "REMOVAL AND INSTALLATION OF UNIFIED METER AND A/C AMP. ".
CHECK CONTINUITY BETWEEN COMBINATION METER AND UNIFIED METER AND A/C AMP.
1. Turn ignition switch OFF.
2. Disconnect combination meter connector and unified meter and A/C amp. connector.
3. Check continuity between combination meter harness connector M20 terminal 1 (R/G) and unified meter and A/C amp. harness connector M56 terminal 26 (R/G).
  1. 1 (R/G) - 26 (R/G): Continuity should exist.
OK or NG
1. OK: Replace combination meter.
2. NG: Repair harness or connector.
Fig 3: Checking Continuity Between Terminal 1 And Terminal 26
Courtesy of NISSAN MOTOR CO., U.S.A.