Troubleshooting Hints

PERFORM BEFORE BEGINNING SYSTEM DIAGNOSIS
Radio Inoperative:
1. For checking a speaker, use a "C" or "D" cell Battery and momentarily connect and disconnect it across the circuits to that speaker while listening for a slight popping sound or watching for the cone of the speaker to move in and out. If either happens, the speaker and circuitry are usually OK.
2. Check I/P 2 Fuse in Rear Fuse Block. If open, check for a short to ground through CKT 440.
3. Check RADIO Fuse in I/P Fuse Block. If open, check for a short to ground through CKT 43.
4. Make sure ground G202 is clean and tight.

Radio Noise:
A noise "sniffer" may be used to aid in troubleshooting Radio noise, see details in Delco Electronics Sound Service Guide. (For definitions of the different types of Radio noise, refer to "Noise Entry."
1. Test the Radio outside with the hood down.
2. Ignition noise on FM indicates a possible defective Ignition System.
3. Check antenna coax connectors for corrosion or bad connections.
4. If a test antenna is used. ground the base of the antenna to the vehicle body.
5. When shielding components, use aluminum foil tape (nickel tape works best for magnetic interference) and ground the end of the shield.
6. Most noise can be found on weak AM Stations near the low end of Radio band.
7. Coated screws or bolts can act as poor grounds.
8. Most hoses are conductive unless they have a white stripe.
9. Before removing a speaker, check all accessible wiring and connectors to that speaker

General:
Check for a broken (or partially broken) wire inside of the insulation which could cause system malfunction but 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).
^ Check for proper installation of aftermarket electronic equipment which may affect the integrity of other systems. Refer to Vehicle / Diagrams / Diagnostic Aids. Diagnostic Aids

Notice To Technicians: Electromagnetic Interference (EMI) can cause a fewer number of stations to be received in one of the three modes. The EMI can be caused by various vehicle components. This may be the cause of the differences in reception. Check for components powered up in the three various key positions. This may eliminate Engine running components, Ignition on components, etc. For example, if the same number of stations are received with the Engine running as when the Engine was off, the components active with the Engine running are not causing the interference.

Development Questions
^ If an equal number of stations are counted in all key positions vehicle related, interference is not indicated. Some vehicle systems may interfere in all key positions.
^ If noise is determined not to be causing interference, refer to "Poor Reception."