Inspection Procedure 9: There is Noise when Starting the Engine.


DIAGNOSIS PROCEDURE


caution
  • Connecting a high tension cable to the noise filter may destroy the noise filter and should never be done.
  • Check that there is no external noise. Since failure to do this may result in an incorrect diagnosis due to the inability to identify the noise source, this operation must be performed.
  • Noise prevention should be performed by suppressing strong sources of noise step by step.
note Capacitor: The capacitor does not pass DC current, but as the number of waves increases when it passes AC current, impedance (resistance against AC) decreases, and current flow is facilitated. A noise suppressing capacitor which take advantage of this property is inserted between the power line for the noise source and the earth. This suppresses noise by earthing the noise component (AC or pulse signal) to the body of the vehicle.
note Coil: The coil passes DC current, but impedance rises as the number of waves increases relative to the AC current. A noise suppressing coil which takes advantage of this property is inserted into the power line for the noise source, and works by preventing the noise component from flowing or radiating out of the line.
Noise type sounds are in parentheses
 Conditions
 Cause
 Remedy
AM or FM: ignition noise (popping, snapping, cracking, buzzing)
  • Increasing the engine speed causes the alternator whine sound to speed up and the volume to decrease
  • Disappears when the ignition switch turned to "ACC".


  • Mainly due to the spark plugs
  • Due to engine noise
  • Check or replace the earth cable.
  • Check or replace the noise capacitor.
Other electrical components
 -
 Noise may occur as the electrical components become older.
 Repair or replace the electrical components.
Static electricity (cracking, crinkling)
  • Disappears when the vehicle is completely stopped.
  • Severe when the clutch is engaged

 Occurs when parts or wiring move for some reason and contact metal parts of the body.
 Return parts or wiring to their proper position.
Static electricity (cracking, crinkling)
  • Various noise are produced depending on the body part of the vehicle.

 Due to removal of the front hood, bumpers, exhaust pipe and muffler, suspension, etc.
 Earth parts by bonding. Cases where the problem is not eliminated by a signal response to one area are common, due to several body parts being imperfectly earthed.