Radio - Distortion/Poor Reception/Whine/Pop

Article No.
95-9-3

05/08/95

^ RADIO - "DISTORTION" - "POOR RECEPTION" - RELATED TO THE IGNITION SYSTEM - 5.0L ENGINE

^ NOISE - "WHINE, POP, DISTORTION OR POOR RECEPTION" IN THE RADIO - IGNITION SYSTEM RELATED - 5.0L ENGINE

FORD:
1994-95 MUSTANG

ISSUE:
Radio interference such as pops, whine, distortion and/or poor reception may be evident on some vehicles. This may be due to any one of the following reasons:

^ Influence of aftermarket devices

^ Loose ground screw at the I/P fuse panel bracket that provides the sub-woofer amplifier ground

^ Loose screw on the ground strap between the engine and frame rail

^ Poor splice in the harness to the rear sub-woofer amplifiers

^ Poor connection at the I/P audio harness connector

^ Crimp over insulation on circuits within Connector C274

^ Poor seating of Connectors C278 and C280

^ Loose antenna connection to the radio or in-line connector behind the glove compartment

^ Poor attachment of the antenna base to the fender due to loose or stripped screws

^ Poor electrical continuity of the shielded hood blanket (AM noise only)

^ Corrosion on terminals of distributor cap and ignition coil (FM noise only)

ACTION:
Follow the Service Procedure to determine the possible cause of the radio interference.

SERVICE PROCEDURE

1. Disconnect all aftermarket devices and inspect for noise in the audio system. If the noise is gone, leave the device disconnected and inform the customer.

2. Check the ground screw at the fuse panel bracket for tightness. Refer to the 1995 Mustang Service Manual, Page 18-01-7, View A.

3. Ensure ground screw (at the ground strap between the engine and frame rail) is tight. Refer to the 1995 Mustang Service Manual, Page 18-01-19.

4. "Wiggle Test" the audio harness at the "Y" Splice located under the back seat. If noise can be introduced into the audio system, install the Overlay Harness (F5ZZ-14588-B) (MACH 460 Sound Systems only) for sub-woofer amplifier.

5. Disconnect and reconnect Connector C275. Refer to the 1994/95 Mustang EVTM, Page 151-8, Grid Area F4, for the location (MACH 460 Sound Systems only).

6. Disassemble connector shell and inspect all circuits in C274 (refer to EVTM, Page 151-9, Grid Area F3) for crimp-over insulation concerns. If insulation crimp-over is found, cut off the terminal end, restrip wire and reconnect terminal. Reassemble the connector shell completely.

7. Disconnect and reconnect Connectors C278 and C280 at the back of the radio. Refer to EVTM, Page 151-10, Grid Area A5, for locations.

8. Check to ensure antenna connection to the radio is secure. Ensure antenna in-line connector behind the glove compartment is secure.

9. Remove the antenna base. Inspect for good contact and check to ensure mounting screws are not stripped. Reinstall the base, being careful not to strip the screws. Torque the screws to 2.17 N-m (1.6 lb.in). Refer to the Service Manual, Page 15-00-21, for removal and installation procedures.

10. If ignition related noise is heard on the AM stations, check grounding of the hood blanket shield. If the resistance is greater than 1.0 ohm through the foil side of the hood blanket and ground strap to vehicle, replace the hood blanket. Be sure to clean the ground contacts.

11. If ignition related noise is heard through the FM band, and Items 1-9 have been performed, replace the Distributor Cap (F5ZZ-12106-AA) and the Ignition Coil (F5zz-12029-A).

PART NUMBER PART NAME

F5ZZ-14588-B Overlay Harness
F5ZZ-12106-AA Distributor cap
F5ZZ-12029-A Ignition coil

OTHER APPLICABLE ARTICLES: NONE

WARRANTY STATUS: Eligible Under The Provisions Of Bumper To Bumper Warranty Coverage

OPERATION DESCRIPTION TIME

950903A Inspect Audio Connections 0.7 Hr.
Throughout The Vehicle
950903B Replace Distributor Cap 0.3 Hr.
And Coil

DEALER CODING
CONDITION
BASIC PART NO. CODE
19B113 57

OASIS CODES: 205000, 207000