Caddy DTS Battery Woes Despite New Power Cell

Had similar issues on my 2005 Cadillac CTS with the 3.6L engine. Initial low voltage symptoms matched exactly, dim lights and weak starts, despite having a new battery. A vehicle diagnostics scan revealed the battery voltage sensor was sending incorrect readings to the computer. This caused the alternator to charge improperly. The sensor is part of the negative battery cable assembly and needs complete replacement when faulty. You can perform basic battery testing at home: Check battery terminal connections for corrosion, Measure voltage across terminals (should read 12.6V when off, 13.7-14.7V while running), Look for loose or damaged battery cables, Monitor dashboard voltage gauge for unusual fluctuations This was a serious issue that needed immediate attention. If left unfixed, it can damage the alternator and electrical systems. The faulty voltage sensor can make the charging system overwork or undercharge the battery. Would recommend getting it checked by a professional who can properly diagnose the charging system. They need specialized equipment to test the voltage sensor function and communication with the vehicle computer.

Thanks so much for that detailed response about the voltage sensor issue. My situation seems identical. I took it to the shop and they confirmed the same diagnosis, faulty sensor in the battery cable assembly. Got it fixed quickly and the car starts perfectly now, plus all electrical systems are back to normal. Just wondering, would you mind sharing what the repair cost in your case? Also, has everything been running smoothly since your fix? No recurring battery charge issues or other electrical problems?

Thanks for the follow up. Yes, my battery health issues were completely resolved after replacing the faulty sensor. The repair cost me 315€ for the complete fix, including labor and parts. The battery voltage has remained stable since then with no more problems starting the car or with the electrical system. The mechanics confirmed that catching the bad battery sensor early prevented damage to the alternator and other components. The low voltage warnings disappeared immediately after the repair. Regular battery maintenance checks show normal charging patterns now. Its been 18 months since the fix and the battery charge stays consistent. No more dimming lights or weak starts. The voltage readings stay right where they should be, around 14V while running. Definitely worth getting it properly diagnosed and repaired rather than risking further electrical issues. My advice would be to still monitor your voltage gauge occasionally just as good practice for spotting any future battery-related problems early.

A few weeks ago I took my Cadillac to my regular mechanic after getting great advice here about the voltage sensor. The diagnosis was spot-on, they found a faulty sensor in the negative battery cable assembly that was causing all my starting and electrical problems. The fix was straightforward. They replaced the entire cable assembly with the new sensor for 290€ total. The car fires up perfectly now, and all the electrical issues have disappeared. The battery charge holds steady, and the voltage readings are exactly where they should be. Really glad I asked here first, it saved time with the diagnosis and prevented any damage to my alternator or other systems. The vehicle diagnostics confirmed it was the sensor and not my fairly new battery causing the problems. Makes me feel better about catching it early. Will definitely keep an eye on the voltage gauge from now on as a precaution, but so far everything is working exactly as it should.