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sprinkles08
sprinkles08, ASE Certified Technician
Category: Cadillac
Satisfied Customers: 22400
Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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2005 Cad, STS, V-6; 101,000 ***** *****, build date was Dec.

Customer Question

2005 Cad, STS, V-6; 101,000 ***** *****, build date was Dec. 2004. I just quit, while being driven ! The inst. panel started flashing, all service codes appeared as I was getting it stopped and pulled of the Hiway! Initially it was dead ! Nothing appeared on the inst.panel ! This is FOB controlled. Finally after several times, of start attempts, it started ! As driving the one mile home, it started jerking & panel flashing ! I noticed the Alt. Voltage was up to over 15.8 ! I replaced the Alt. Same problems exist ! Is possibly the ECTs damaged ? Can they be tested, off the car ? I live in a remote County in Idaho. Roger
JA: Thanks. Can you give me any more details about your issue?
Customer: My name is Roger. What is an Example of what additional info could be of assistance to you ? Roger
JA: OK got it. Last thing — Cadillac Mechanics generally expect a deposit of about $18 to help with your type of question (you only pay if satisfied). Now I'm going to take you to a page to place a secure deposit with JustAnswer. Don't worry, this chat is saved. After that, we will finish helping you.
Submitted: 1 year ago.
Category: Cadillac
Expert:  sprinkles08 replied 1 year ago.

Hello and welcome to JustAnswer!

If it's overcharging it could be the alternator itself, a shorted control circuit, an internal failure in the powertrain control module, or the PCM could be seeing the wrong battery voltage due to a wiring issue. If it sees voltage is lower than it really is then charging voltage will drive higher. It's also possible for the battery to cause charging issues.

If the alternator has been replaced and symptoms are exactly the same then you should be able to rule it out. I've seen quite a few issues with aftermarket alternators but it wouldn't be likely for one to cause overcharging.

Do you know what fault codes are setting in the PCM?

Did the problem start after a repair, ump start, accident, etc?