Test the radio with the vehicle outside and the hood down.
Check radio reception in an area away from tall buildings, metal structures,
power lines, fluorescent lighting, and power tools.
Ignition noise on FM indicates a possible defective Electronic Ignition
(EI) System. Refer to "Secondary Ignition Noise (from spark plugs or wires)" in the
Noise and Reception Performance Complaints section of this service manual.
Check for proper installation of aftermarket electronic equipment which
may affect the integrity of other systems.
Check antenna coax connectors for corrosion or bad connections.
If a test antenna is used, ground base of the antenna to vehicle body.
Coated screws or bolts can act as poor grounds. Do not use Loctite® 242
Threadlocker, or equivalent material, on bolts because it will insulate the ground
path.
Before removing a speaker, check all accessible wiring and connectors
to that speaker.
Check for a broken, or partially broken, wire inside of the insulation
which could cause system malfunction, but would still prove good in a continuity/voltage
check with a system disconnected. These circuits may be intermittent or resistive
when loaded, and if possible, should be checked by monitoring for a voltage drop with
the system operational (under load).
Make sure that the customer does not have an aftermarket mobile electronic
component, such as a cellular telephone, that has been removed before the vehicle
was left for service. This is extremely important, because that component may be emitting
the frequencys that are causing the complaint.
Try to duplicate condition (listen to AM or FM, start vehicle, put in
a good CD or cassette, test switches, etc.).
Refer to
Symptoms - Entertainment
for the appropriate diagnostic
procedures for hardware related failures or performance complaints.