Many conditions that affect radio operation may be corrected
without removing the radio from the car. Verify the condition, and follow
the diagnostic procedures in order to isolate and correct the condition.
Before attempting to diagnose any audio system problems, ensure
that you fully charge the battery.
If the voltage is below 9 volts, incorrect diagnosis may result.
Troubleshooting Hints
| Important: When testing for audio reception or noise, the vehicle should be outside
away from metal buildings and utility lines, with the hood and rear compartment
closed.
|
• | Inspect that the antenna connector and the antenna coaxial cable are
clean and tight. |
• | For reception concerns, first determine if the customer is within
the listening area of the stations he or she is attempting to receive. |
• | Compare the customers vehicle to another of similar model and
audio system to determine if the condition is abnormal. |
• | Most normal audio noises can be found on weak stations near the
low end of the band. This noise is considered to be a normal condition. |
• | Check for any aftermarket equipment that may have been installed
on the vehicle. If aftermarket equipment is found disconnect it and check
if the audio noise is still present. |
• | If the noise is only from one speaker check for the flowing before
speaker replacement: |
- | Verify that the speaker connections are clean and tight. |
- | Verify that the speaker mounting is tight. |
- | Inspect for loose or incorrectly installed speaker or surrounding
trim. |
• | Ignition noise on the FM band may be a indicator of a ignition
system breakdown. |
• | Inspect that all vehicle grounds are clean, tight and free of
corrosion. |
• | Inspect the rear defogger grid lines for breaks or dark spots. |
• | Inspect the connections at the radio antenna module and ground
coil to ensure that they are clean and tight. |
Identifying Concerns
Important: When testing for audio reception or noise, the vehicle should be outside
away from metal buildings and utility lines, with the hood and rear compartment
closed.
- To help isolate the source of the noise, identify the ignition switch
position that the noise is most noticeable:
• | Turn the ignition switch to the accessory position and listen
for the noise. |
• | Turn the ignition switch to the run position with the engine off. |
• | Turn the ignition switch to the run position with the engine running. |
- Turn the ignition switch to the position that the noise was most
noticeable.
- Remove the vehicle fuses and circuit breakers one at a time until
the noise has been eliminated.
- Identify what systems or components are powered by the fuse.
- Reinstall all fuses and circuit breakers.
- Disconnect the components power by the fuse one at a time until
the noise has been eliminated.
Corrective Action
• | Inspect the ground integrity of the component or system causing
the noise. |
• | Malfunctioning and marginal components such as relays and solenoids
may cause noise and/or poor reception. |
• | Always use a braided ground strap when applying grounds and keep
the ground strap as short as possible. |
• | If the noise source is found to be coming from the vehicle harness: |
- | Route the antenna cable separately from the wire harness that
is emitting the noise. |
- | Use aluminum or nickel tape in order to shield the antenna cable.
Try varying the following techniques: |
• | Try just adding the tape before adding a ground strap to the tape. |
• | Wrap a ground strap 360° around the tape, securing
the other end of the strap to chassis ground. |
• | Add a ground strap to both ends of the tape. |
| Important: When installing suppression devices, signal wires such as sensor and
communication circuits should not be suppressed, battery and ignition voltage
circuits are the best choices for suppressing.
|
• | Capacitors work best on switch pops and low frequency noise. |
• | Filters work best on high frequency whines and static. |
• | After adding any suppression device, inspect all of the vehicle
systems (including those not related to the audio system) for proper operation
and function. |
• | Whenever possible, make a test harness that includes filters or
capacitors. Always inspect the effectiveness and operation before permanent
installation. |
• | If an audible pop is induced from a switch operation, perform
one or more of the following capacitor applications, as necessary: |
- | Add a capacitor across the contacts of the switch. |
- | Add a capacitor from the battery positive voltage (B+) side of
the switch to chassis ground. |
- | Add a capacitor from the ground side of the switch to chassis
ground. |
• | Use the following available noise suppression devices: |
- | 220 mF (50 V) capacitor |
- | Turn signal suppression |
- | 21 in. braided ground strap |
- | 19 in. braided ground strap |
- | 10.5 in. braided ground strap |
- | 8.5 in. braided ground strap |
Generator Whine Concerns
- Inspect the ground terminal and cable for high resistance.
- Inspect the generator and brackets for loose or coated mounting
bolts.
- Inspect that the ground straps between the engine and the frame
are clean and tight.
- If the noise is still present, inspect the charging system for
proper operation. Refer to Symptoms in Engine Electrical.
- Install a filter in the battery voltage feed circuit to the radio.
- If the noise is not eliminated, install the filter in the following
variations:
• | Install the filter with the single wire side toward the radio
and the ground wire attached to chassis ground. |
• | Remove the ground to the filter. |
• | Reverse the filter so the two-wire side is toward the radio with
the ground wire attached to chassis ground. |
• | Remove the ground from the filter. |
- Install a filter in the ignition voltage feed to the radio.
- If the noise is not eliminated, install the filter in the following
variations:
• | Install the filter with the single wire side toward the radio
and the ground wire attached to chassis ground. |
• | Remove the ground to the filter. |
• | Reverse the filter so the two-wire side is toward the radio with
the ground wire attached to chassis ground. |
• | Remove the ground from the filter. |
- If the filter causes delays in the radio when turning ON or OFF,
or other problems, remove the filter and Install a 0.47 mF
capacitor to chassis ground.
- Before reassembling the vehicle, remove any unneeded filters.
- Inspect all of the vehicle systems (including those not related
to the audio system) for proper operation and function.