Alt or ECU on 2003 Cadillac CTS

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While driving my car the TC, break light, battery, and my battery was reading at 9 Volts,and my suspension light came on, i was woundering if it could be the Alternator or the ECU that is causing the problem or something else?
(1) Answer
If you have a multimeter you'll be able to check the alternators output at the time of the problem. Eventhough many vehicles will illuminate multiple lights when the alternator fails remember to also check your PCM operation by monitoring the data values while the engine is running. Be sure to compare the data values with the calibrated values for your vehicle. Good luck.