Speed Sensitive Volume System Does Not Work

WARNING: This page is about a different car, the 2003 Infiniti G35. However, it is still accessible from the selected car via links, so may be relevant.

VEHICLE SPEED OPERATION CHECK
Does speedometer is operated normally?

Yes or No

Yes : GO TO 2.

No : Check combination meter trouble diagnosis. Refer to, "COMBINATION METERS " article.
HARNESS CHECK
1. Turn the ignition switch OFF.
2. Disconnect audio unit connector and combination meter connector.
3. Check continuity between audio unit harness connector M39 terminal 18 (W/G) and Unified meter and A/C amp. harness connector M19 terminal 19 (W/G).
  1. Continuity should exist.
    
    Fig 1: Checking Continuity Between Audio Unit And A/C Amp.
    Courtesy of NISSAN MOTOR CO., U.S.A.
4. Check continuity between audio unit harness connector M39 terminal 18 (W/G) and ground.
  1. Continuity should not exist.
OK or NG

OK : GO TO 3.

NG :
- Check connector housings for disconnected or loose terminals.
- Repair harness or connector.
VEHICLE SPEED SIGNAL CHECK 1
1. Connect audio unit connector.
2. Turn the ignition switch ON.
3. Check voltage between audio unit harness connector M39 terminal 18 (W/G) and ground.
  1. Approx. 3.5V or more
    
    Fig 2: Checking Voltage Between Audio Unit And Ground
    Courtesy of NISSAN MOTOR CO., U.S.A.
OK or NG

OK : GO TO 4.

NG : Replace audio unit.
VEHICLE SPEED SIGNAL CHECK 2
1. Connect combination meter connector.
2. Start engine and drive vehicle at more than 40 km/h (25MPH).
3. Check the signal between audio unit harness connector M39 terminal 18 (W/G) and ground with CONSULT-II or oscilloscope.
  1. 18 (W/G) - Ground : Refer to " Terminals and Reference Value for Audio Unit for Bose System ".
    
    Fig 3: Checking Signal Between Audio Unit And Ground With CONSULT-II Or Oscilloscope
    Courtesy of NISSAN MOTOR CO., U.S.A.
OK or NG

OK : Replace audio unit.

NG : Check combination meter system. Refer to, "COMBINATION METERS " article.