Radio, Stereo, and Compact Disc: Testing and Inspection

TROUBLESHOOTING HINTS:
AUDIO SYSTEM DIAGNOSTIC OVERVIEW
1. Verify customer complaint.
2. If technical assistance is required, have all the pertinent information available before placing the call.

IDENTIFYING CONCERNS
^ Check for technical service bulletins.
^ Check for stored diagnostic trouble codes.
^ For reception concerns, determine if the station is obtainable in the customer's listening area.
^ To test for audio reception/noise, position the vehicle outside of the building with the hood down.
^ Duplicate the customer's complaint before trying to diagnose the system. Have the customer demonstrate the condition. Test drive the vehicle with the customer and then test drive another similar model vehicle (with a similar audio system) to do a comparison of the two vehicles to determine if the condition is abnormal.
^ Before diagnosing, identify components, their features and the customer's complaint.
^ Determine if any aftermarket equipment is installed on the vehicle. Disconnect the aftermarket equipment and determine if the customer's complaint still exists.
^ Perform the following steps to identify a noisy component:
1. Identify ignition key switch position in which the noise appears, such as: accessory, key ON engine not running, and key ON engine running.
2. REMOVE fuses one at a time until the complaint condition has been eliminated.
3. Mark the complaint fuse(s) and reinstall all fuses and circuit breakers.
4. Refer to Power Distribution and Fuse Block Details to identify all systems and components powered by the complaint fuse(s).
5. Disconnect the components powered by the complaint fuse(s) one at a time until the complaint condition has been eliminated and the noisy component is identified.
6. Check the ground integrity of the complaint causing component.
^ An interference condition is NOT necessarily an audible noise.
^ Most noises can be found on weak stations near the low end of the band and are considered to be a normal condition.
^ Ignition noise on FM could indicate a possible defective ignition system.
^ Malfunctioning and marginal components, relays, and solenoids may induce noise and/or poor reception.

CORRECTIVE ACTION
^ Use proper tools for diagnostics and repairs.
^ Follow ESD guidelines.
^ Use available noise suppression devices:
- 220 mF (50V) capacitor
- 0.47 mF capacitor
- Fuse block capacitor
- Feed through capacitor
- Filter package
- Turn signal suppression
- Fuel pump suppressor
- 21 inch braided ground strap
- 19 inch braided ground strap
- 10.5 inch braided ground strap
- 8.5 inch braided ground strap
^ Utilize the test tape to optimize proper audio diagnostics.
^ If the condition requires the radio to be sent to the service center, describe the symptoms on the warranty form accurately. Along with the warranty form, send a copy of the Service Writer check List with the unit.
^ Do not leave a tape in the car Extreme heat could cause permanent damage.
^ Cassette tapes could be damaged if not stored in the case. The vibration in the vehicle can cause the tape to unwind inside the cartridge.
^ Before removing speaker(s), check all connectors and wiring to the speaker(s). Examine the connectors for bent or loose pins.
^ If a test antenna is used in diagnostics, ground the antenna base to the vehicle body and do not hold the mast.

Important:
^ Check the antenna coax connectors for corrosion or bad connections/crimps. Route coax separately from the other wires. Shield antenna coax interconnections with aluminum or nickel tape.
^ Check all vehicle grounds, NOT just radio and antenna grounds.
^ Coated screws or bolts can act as poor grounds.
^ Always use a braided ground strap when applying grounds. Keep the ground strap as short as possible, the shorter the ground strap the better.
^ When shielding the dash, wires, hoses (most hoses are conductive unless they have a white stripe), etc., use aluminum foil tape or nickel tape to shield against magnetically induced interference. For optimum results, try varying the following ground techniques:
- Add a ground at both ends of the tape.
- Add a ground to just one end of the tape.
- Do not add ground to the tape.
^ When shielding a harness with tape, attach a ground strap to the end of the tape and then wrap the strap 360° around the tape securing the other end of the strap to a known good chassis ground.
^ Any interference is best corrected by suppression at the source of the interference, if possible.
^ Care should be used when applying suppression. Signal wires (such as sensor outputs, clock, and communication circuits) CANNOT be suppressed. Battery and ignition wires can be suppressed. After adding any suppression, all vehicle systems (even those not related to the audio system) should be checked for proper operation and function.
^ Interference can usually be eliminated by shielding/grounding or suppressing.
^ Capacitors work best on switch pops and low frequency noise. Filters work best on high frequency whines and static.
^ Whenever possible, make a test harness that includes filters and capacitors. Always check the effectiveness and operation before permanently installing a FIX.
^ Recommended capacitor application for an audible pop induced from a switching operation is:
- Add a capacitor across the contacts of the switch.
- Add a capacitor from the hot side of the switch to ground.
- Add a capacitor to each side of the switch to ground.
^ If a complaint condition is only present with the ignition key in the RUN position and the engine running, perform the following checks:
- Check the integrity of the ignition system (proper spark plug wire routing, no misfiring, etc.).
- Check the integrity of the engine compartment grounds.
- Check for malfunctioning relays, solenoids, or other components which may be inducing noise or poor reception.
- Check the ground integrity of the complaint causing component.
^ For noise and/or poor reception, perform the Antenna System Test and make the necessary repairs.

GENERATOR WHINE CONCERNS
Inspect:
^ Check the ground terminal on the battery.
^ Check for coated mounting bolts on the generator bracket.
^ Check for a faulty mounting of the generator to the engine.
^ Make sure all ground straps between the engine and a the frame are clean and tight.
^ Try the following fixes:
1. If noise is still present, check the charging system.
2. If the charging system is functioning normally, check for technical service bulletins on generator whine.
3. Install a filter in the battery feed to the radio.
4. Try installing the filter with the following variations if noise is not eliminated.
- INSTALL the filter with the single wire side toward the radio and the ground wire attached to a good 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 a good ground.
- REMOVE the ground from the filter.
5. If noise is still present, install another filter in the ignition feed to the radio. Install using the same variations as the first filter. If the installation of this filter causes turn ON or turn OFF delays or other noticeable performance concerns, REMOVE it and INSTALL a 0.47 mF capacitor to ground in its place.
6. REMOVE any unneeded filters after Repair, before reassembling the vehicle.




Radio Does Not Retain Stations In Memory Or Clock Does Not Operate




Radio Illumination Lamps Do Not Come On




Display Dimming Function Will Not Operate




Display Is Inoperative, No Sound From Any Speaker




No Sound From One Speaker




Tape Player Is Inoperative




Tape Plays Weak, Slow Or Garbled







Noise And/or Poor Reception







Antenna System Test




USE AND CONSTRUCTION OF A NOISE SNIFFER
The noise sniffer can be used along with the vehicle's Radio to locate hot spots which are generating Radio noise interference. These hot spots can be found in the harnesses, in the upper part of the dash or even between the hood and the windshield.
The sniffer can be made from an old piece of antenna lead-in from a mast or power antenna. The longer the lead-in the better. Make the noise sniffer. The two inch section stripped back becomes the antenna when the sniffer is plugged into the Radio's antenna socket. It can then be used to probe and search out hot spots. To use the sniffer:
1. While listening to the complaint noise, disconnect the antenna and plug the sniffer into the antenna socket.
2. Turn the Radio volume up.
3. Search for the noise source, keeping fingers off the 2 probe.
When checking for noise on a wire, the best results will be achieved when the sniffer is placed parallel to the wire.

CUSTOMER'S TIPS
HOW TO ENJOY FM STEREO
1. Select Stations Within Range -The best FM fidelity will be obtained from stations within the 10-40 mile range. Beyond that, noise or flutter may begin to appear due to the line of sight range limitations of FM signals.
SOLUTION: Reduce treble response by moving the treble control down (or to the left) in fringe areas. On EQ Radios, slowly slide the 10K control down.
2. Realize Tall Structures Can Interfere - Tall buildings or hills may cause shadows or cancellation of FM signals (this is similar to the ghost or flutter effect seen on television sometimes when airplanes are flying in the vicinity). It will sound like a pop or momentary hiss.
SOLUTION: Reduce the treble or 10K setting to a lower volume.
3. Interference From Another Station - Although the circuits in these receivers are the most advanced available, there are rare instances where a station being listened to will be interfered with by another station. This only happens when the stations are on almost the same frequency and certain geographical criteria are present.
SOLUTION: Select another station or switch to a tape.

HOW TO ENJOY AM
Reception Characteristics
AM does not have the flutter characteristics of FM (caused by tall buildings, hills, etc.). However, it is subject to interference from powerlines, neon signs, atmospheric conditions and unwanted stations.

WAYS TO REDUCE NOISE
1. Move treble control down.
2. mile to a stronger station.