1.Inspection of antenna (with radio turned on)
Turn on the radio with the ignition switch in the ACC position and check the following items:
(1)Check antenna cable for open circuit
Turn the volume to the maximum.
Rub the antenna mast with a piece of metal and check if a scratching sound comes from the speakers.
If a scratching sound comes from the speakers, there is no open circuit in the antenna cable.
(2)Check antenna mast for looseness
Tune in a signal from an AM station.
Tap the antenna mast with your finger and check if any noise comes from the speakers.
If noise comes from the speakers, there is a bad connection in the antenna mast.
(3)Check antenna sensitivity
Tune in a weak signal from an AM station.
Touch the antenna pole with your hand.
If the sound becomes louder, the antenna’s sensitivity is bad.
If the sound fades or does not change, the antenna sensitivity is okay.
Make sure that no part of your body is touching the vehicle body.
2.Inspection of antenna (with antenna cable disconnected from radio receiver)
(1)Measure insulation resistance between antenna mast and vehicle
Resistance: Several MΩ or greater
The above check has the same meaning as the check of the insulation resistance between the shield wire and the core wire of the antenna cable.
Ordinarily, a capacitor is incorporated into the core wire of the antenna cable.
Therefore, the insulation resistance between the core wire and shield wire cannot be checked on the plug side of the antenna cable.
(2)Measure resistance between shield of coaxial cable and vehicle body
The coaxial cable’s shield wire is grounded on the antenna side and the radio receiver side.
Therefore, there must be no faulty contact on either end of the coaxial cable.
3.Replacement of motor antenna mast
(rack cable and pinion type)
In the case of a rack cable and pinion type motor antenna, the rack cable and pinion are used to extend and retract the antenna mast.
This type of motor antenna mast can be replaced easily by rotating the motor.
However, the procedure for the removal of the antenna mast in a variable-height type antenna differs slightly from that for a non-variable-height type.
Mast replacement requires one person to turn the radio on or off, on the command of the technician who is handling the mast.