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Electrical System 12-145
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05745159 1. Identify ignition switch key position in which the noise 2. Remove fuses one at a time until the complaint condition 3. Mark the complaint fuse(s) and reinstall all fuses and 4. Identify all systems and components powered by the 5. Disconnect the components powered by the complaint 6. Check the ground integrity of the complaint causing noise. • Most noises can be found on weak stations near the low end of the band and are considered to be a normal condi- • Malfunctioning and marginal components, relays, and solenoids may induce noise and/or poor reception. 7. Check for a broken (or partially broken) wire inside of the
Corrective Action
• Use proper tools for diagnostics and repairs. —Filter package P/N 05744279 Utilize the test tape /CD Diagnostic Kit Kent-Moore • If the condition requires the radio to be sent to the ser- vice center, describe the symptoms on the warranty • Do not leave a CD disc or tape in the vehicle. 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 • Use available trouble trees. wiring to the speakers. Examine the connectors for bent • If a test antenna is used in diagnostics, ground the an- tenna base to the vehicle body and do not hold the mast.
NOTE:
Check the antenna coax connectors for corrosion or bad connections/crimps. Route coax separately from the other • Coated screws or bolts can act as poor grounds. grounds. Keep the ground strap as short as possible, the • When shielding the dash, wires, hoses (most hoses are conductive unless they have a white stripe), use alumi- —Add a ground at both ends of the tape. • When shielding a harness with tape, attach a ground strap to the end of the tape and then wrap the strap 360 • 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 communica- • 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 • Whenever possible, make a test harness that includes fil- ters and capacitors. Always check the effectiveness and • Recommended capacitor application for an audible pop induced from a switching operation is: —Add a capacitor across the contacts of the switch. 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 —Check the integrity of the engine compartment grounds. —Check for malfunctioning relays, solenoids, or other components which may be inducing “noise” —Check the ground integrity of the complaint caus- ing component. • For noise and/or poor reception, perform the antenna system test and make the necessary repairs.
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