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sprinkles08, ASE Certified Technician
Category: Australia Car
Satisfied Customers: 22394
Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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Grand cherokee: I have a 1999 v8 4.7 jeep grand cherokee

Customer Question

Hi I have a 1999 v8 4.7 jeep grand cherokee . the radio works fine wen motor not running . When motor is running radio can not be used as reception is not good , volume goes up and down with static all the time . Its the same playing C Ds . turn motor off radio works fine . Can anyone help
new zealand
Submitted: 2 years ago.
Category: Australia Car
Expert:  sprinkles08 replied 2 years ago.
Helo and welcome to JustAnswer!
If the problem only happens with the engine running then the problem is almost surely interference from the charging system. The problem could be the battery, voltage drop in a cable, the alternator itself, or it could be a poor radio ground. I would recommend checking battery and alternator connections, you can have the battery load tested and the alternator can also be tested for excessive ripple.
If no problems are found then the radio's (and amplifier if equipped) powers and grounds should be tested. A redundant ground could also be added at least for test purposes.
If all wiring can be ruled out, the antenna cable is in good condition, connections are clean and tight, etc then odds are the alternator will need to be replaced.

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