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Hello everybody. I have a 2012 CTS Coupe (base model 3.6 RWD automatic). Now and then while driving, ALL power will cut out, except to the engine, since the car never dies, and the radio cuts out for a split second but very quickly returns and the radio itself never powers down (assuming the factory amplifier needs a sec to come back on or something). It will last a couple seconds or so, with no power steering, AC, dash lights, etc, and if I have the headlights manually off or the TC manually off, they would be reset to being on when the power returned. Otherwise, once the electrical comes back on there is no strange behavior or lights. I have not yet identified the issue, but I can rule out a few things. Those are as follows:
  • I have a new H.O. alternator
  • Brand new battery
  • Upgraded power/ground cables
  • Nothing loose or corroded
  • No CEL, no codes, nothing flashing on the dash, etc
  • Monitoring the voltage constantly (to make sure my stereo/amp and charging system are working properly) there is never a sudden drop or spike in voltage
  • Does not seem to coincide with turning, braking, or accelerating
  • Headlights, AC, wipers, defrost, etc, being on or off doesn't seem to make a difference. I do always disable TC and usually the automatic headlights, but I can't imagine having either off would freak anything out?
  • Cannot remember if the issue occurred with the stock radio or not. I did not have the stock radio for very long.
  • Has yet to happen at night, thankfully, but I rarely drive at night to begin with, so might be coincidence.
  • This is the only issue I have with the car, Everything else, after 46k miles of documented service with a Cadillac dealer (40K+ of that with another owner), has been perfect.
  • No I have not taken it in for service or to have a dealer check it out. Its a 2012 far out of warranty and I would rather not pay Cadillac shop prices to likely not have anything found out (since the issue is so sporadic)
I have installed an aftermarket stereo using the Metra/AXXESS kit, and have an aftermarket amplifier, but all wiring and connections have been double/triple/quadruple/+ checked over the course of installing the garbage Axxess module and getting that to work right to start with, so if it is a short or something else electrical it would have to be something unrelated under the hood, or something somewhere I have not meddled.

I have two 12 inch subs installed in an infinite-baffle configuration behind the rear seats, and at first I thought it was maybe due to the amplifier pulling too much power and freaking out the car computer or maybe the notoriously-garbage Axxess control box, but it seems to not be related to the radio/amp as it occurs without them in the equation. It also happened with the factory alternator and the old battery.

I tried searching the forums for similar issues, and did find a few, but they seemed specific to turning thru intersections, whereas my issue happens without turning or making any sudden speed/directional changes. Honestly I am worried it is related to the Axxess module. Sorry for the long first post, I am just hoping maybe someone has any clues or something I can do to test things I have not yet thought of. Maybe someone has seen the exact same thing? Thank you in advance, searching Google and the forums has not turned up anything of real use, and I really love my car, so I would like to resolve any issues
 

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2014 ELR
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As I read the list, and came to "upgraded power and ground wires", I knew we were eventually going to come to aftermarket stereo equipment. I know you've triple checked everything. However... start by disconnecting all the aftermarket stuff. See if the problem repeats. Connect one thing at a time until the problem happens.
 

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2011 CTS Coupe FE3, 2003 Thunderbird, Gone 2013 ATS, 02 Deville
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Jayoldschool is correct, start disconnecting the main power for ALL the aftermarket power units you have and see how long it goes with no shutdowns.
 

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Hey, welcome aboard. I agree with the posts above as well.
These cars are finicky and your CTS is unhappy with something you did or undid.

Anyways, when you find it, you'll be like... faaaaq!
 

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Discussion Starter #5
Sorry for late reply! And sorry my comment got so long-winded, I have trouble keeping focused to a train of thought ha. Forgot where I had asked this and for some reason I never got any emails for replies other than the first one so I totally forgot about this.... Thank you for the suggestions, and thank you for not being rude and assuming I was incompetent. I haven't participate in a car forum in almost 10 years due to a toxic culture at the last one I was a member... I was able to locate the issue, though. I have double and triple checked everything like I said, but, I forgot to state the stock cables are all still in place as well, in their stock positions with stick connections. Everything has been tested with a multimeter as well to verify all connections are solid and working as expected and the alternator and battery are both within spec.

What I found the issue to be, was a microsecond of severe voltage loss. In a sudden burst my amp pulls a LOT of power, dropping voltage under 12v for such a short amount of time its almost unnoticeable. Somewhere mid-high 11s. I know, sounds like it would be the cause of improper wiring, faults, shorts, bad connections, etc, and I hope it doesnt come off rude when I say that is definitely not the case (trust me, that would be what I would tell someone else if they asked me the same questions haha). Anyways, so the bass would hit, voltage would drop for a fraction of a split second, and that seems to really make the computer not happy. The dash readout does not update fast enough to notice this, but using an ODB reader I watched both the voltage at the OBD port and the car's own reported voltage, at update increments as fast as my scanner supports. Voltage drop under 12v, however short-lived and no matter how far below 12v, the entire stock electrical system would reset except my stereo. See below for a screenshot of an instance where the issue occurred. I have since installed a bank of super-caps (90-ish farads) and voltage is rock-steady under all circumstances. No dimming lights, car starts faster, no more computer funkiness, etc. No voltage drop no matter what I do.
586087




I also want to quickly state that I am not one of the folks that piss off the neighbors with my stereo ha. My setup is specifically designed for ME to enjoy, not for others, which is one reason I went infinite baffle in a car that it is quite difficult to achieve ha.. It gets wicked low, but isnt wicked loud.
 

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Nice update.
Glad to hear you found your issue (y)
 

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2011 CTS Coupe FE3, 2003 Thunderbird, Gone 2013 ATS, 02 Deville
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Electrical spikes are always a big problem, Glad you found the issue and thanks for the report back.
Happy motoring.
 

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2009 SRX V6 RWD, 2011 CTS Premium Coupe
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Sorry for late reply! And sorry my comment got so long-winded, I have trouble keeping focused to a train of thought ha. Forgot where I had asked this and for some reason I never got any emails for replies other than the first one so I totally forgot about this.... Thank you for the suggestions, and thank you for not being rude and assuming I was incompetent. I haven't participate in a car forum in almost 10 years due to a toxic culture at the last one I was a member... I was able to locate the issue, though. I have double and triple checked everything like I said, but, I forgot to state the stock cables are all still in place as well, in their stock positions with stick connections. Everything has been tested with a multimeter as well to verify all connections are solid and working as expected and the alternator and battery are both within spec.

What I found the issue to be, was a microsecond of severe voltage loss. In a sudden burst my amp pulls a LOT of power, dropping voltage under 12v for such a short amount of time its almost unnoticeable. Somewhere mid-high 11s. I know, sounds like it would be the cause of improper wiring, faults, shorts, bad connections, etc, and I hope it doesnt come off rude when I say that is definitely not the case (trust me, that would be what I would tell someone else if they asked me the same questions haha). Anyways, so the bass would hit, voltage would drop for a fraction of a split second, and that seems to really make the computer not happy. The dash readout does not update fast enough to notice this, but using an ODB reader I watched both the voltage at the OBD port and the car's own reported voltage, at update increments as fast as my scanner supports. Voltage drop under 12v, however short-lived and no matter how far below 12v, the entire stock electrical system would reset except my stereo. See below for a screenshot of an instance where the issue occurred. I have since installed a bank of super-caps (90-ish farads) and voltage is rock-steady under all circumstances. No dimming lights, car starts faster, no more computer funkiness, etc. No voltage drop no matter what I do.
View attachment 586087



I also want to quickly state that I am not one of the folks that piss off the neighbors with my stereo ha. My setup is specifically designed for ME to enjoy, not for others, which is one reason I went infinite baffle in a car that it is quite difficult to achieve ha.. It gets wicked low, but isnt wicked loud.
You were told it was in the aftermarket garbage, and there you go. It could be worse. A guy with a 7th generation Monte Carlo lost his headlights.
 

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This is why people stop posting back.
 
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