2003 Chevy Monte Carlo Theft-security system and volt gauge

2003 CHEVROLET MONTE CARLO
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TECHMECH57
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Electrical problem
2003 Chevy Monte Carlo 6 cyl Front Wheel Drive Automatic

Hi every one and thanks for all your help in the past. Never had a problem with car until battery needed to be replaced. Now about half the time when you start car the volt gauge stays down around 8 volts and the radio locks up because the theft system locks it up. Car runs fine other wise. Check the alternator and new battery and battery connections. All seems to be good. Hope you can help. Dont know much about the theft systems in these cars. Thanks again, Dennis
Apr 12, 2009 at 3:36 PM
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JAMES W.
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You may need the code for your alarm system to reprogram after you change batteries. You can call your local GM dealer with the VIN #, and they should be able to help you. Many times the access code is written in the owner's manual. You could check there.
On the low volt gauge. If you connect a volt meter to the poles on the battery and start the engine, the volt reading should be from 12.5 to 14.5 volts. Maybe the alternator is only putting out 8 volts on start.
Apr 12, 2009 at 9:30 PM
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TECHMECH57
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Thanks for the info. Will check and see if the code is in the manual. Tested the charging system and it is fine so dont know if the 2 problems are related since they either both work or dont at the same time. Once I get the code for the theft system does it get enter with the radio controls? Thanks again
Apr 12, 2009 at 11:56 PM
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JAMES W.
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Your security system really have nothing to do with the volt gauge. Let's get the security back on track and if the gauge problem persists, we can go there next.
Apr 13, 2009 at 12:04 AM
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TECHMECH57
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Did the reprograming thing but still have the same problem. Doesnt act up all the time, but when it does both the radio and volt gauge act up at the same time. So they must have something in common. The charging system checks out fine. Is there a ECM or BCM that both systems use? Thanks for your help. Dennis
Apr 21, 2009 at 11:45 PM