2005 z51. Oil Catch Can, K&N filter, Centerforce DYAD clutch with lightweight 13lb flywheel. Everything else performance is stock.

A few weeks ago, my stereo/radio started sticking on or off. It would be fine when I'd first get in and start driving, but then randomly the stereo would:
1) shut the screen off and the stereo would become locked wherever it was (several times with the volume way up after some highway driving). A couple of times it would restore itself, but most times I would have to shutdown and restart it.
2) shut the screen off and the stereo and NAV would be completely inoperable. A couple of times it would restore itself, but most times I would have to shutdown and restart the car.

Yesterday I got in, drove 1mile to the gas station and filled up. I then tried to restart the car. It gave me a check engine light and the Battery Voltage came up on the DIC showing 11.5volts. I gave it a few more tries and on the 3rd one, it fired right up and zoomed back up to 13.9volts. I drove to an appointment and after two hours there, the car fired right back up. Again, 11.5volts and then it climbed back up to 14.0volts. When I got off the freeway, the voltage dropped to 13.4volts and the stereo turned off...

I pulled into Autozone and had them do their battery test. Battery test pass, Alternator test pass, diode test pass, excessive ground test pass, regulator test pass.

The battery was replaced <6months ago. The alternator is apparently good. The test said no grounds. Why is the voltage swinging so wildly now?? It used to just go from 14.0-14.2 volts pretty reliably.

 

You said they checked the battery. How did they check it? Even a new battery can be bad and it sure sounds like yours could be bad. One thing I did with my Bose radio/Nav when the CD portion stopped working was disconnect the battery. That fixed it. You might want to try that before anything else. Good luck and keep us posted.

 

sometimes the harmonic balancer can slip causing the issue....you may want to take it somewhere and have someone look at it....(not auto zone or a parts place)

 

If it happens when you hit a bump turn or something like that it could be a loose battery plate.
good luck
Robin

 

Loose connection battery to starter solenoid can cause strange voltage problems.

 

you dont happen to have NGK plugs in the car do you?

 

My thought also. But the voltages that you are reporting are not erratic. When the car is first started, the voltage is usually higher...like 14+. When the car is warmed up, it can be normal to drop into the 13s. 11.5 when the engine is not running is normal also. I don't mean that the starting issue is normal, but your voltages are.

 

The battery has been disconnected a couple of times lately. Before I noticed the erratic voltages, I was just hunting down the troublesome radio/stereo. Part of that process was disconnecting the battery a couple of times and checked the 3 fuses associated with amp and stereo.

How do you check for a loose battery plate? A couple of times I've really romped the throttle, I triggered the power loss. Not saying it happens every time, but it hasn't been ruled out.

Like previously mentioned, it seems like sudden acceleration may be a triggering event. MAY. Where is that battery to starter cable routed?

No sir. I have AC Delco's in there.

 

Then why would twice now the car give me the Check Engine light and switch the DIC to the Voltage indication, while failing to start?

 

It sounded to me like you got the check engine light and the 11.5 volts when the car was not running...this is normal and will happen any time the ignition is on without the engine running.

 

i do, i havent noticed anything different

 

In the past my car would definitely get the 14.0volts gremlins. After a weekend at the track and only running for the 20minute sessions while running Torque bluetooth adapter and charging my phone, the voltage would drop to 14.0 volts pretty consistently. When this would happen the car would fail to recognize my keyfob, would have trouble with the column lock, and would fail to initialize my memory seat position. After a good monday morning charge, all would be fine.

I guess I don't understand why they change in behavior. It used to never go below 14.0volts. Now <13.5 consistently?

 

Anything from 13.2 to 14.5 or so is normal when the car is running. I'm not saying that you don't have some other problem but 'dropping below 14 volts' is not one of them. On a hot day, at idle, with A/C, headlights and engine fan running, a dip into the 12s is not unheard of.

 

It certainly doesn't happen with everyone but NGKs causing erratic charging system operation is a known issue here on the forum.

 

With all that stuff on here when its over 105° outside my voltage actually dips into the high 11s. Never got any warnings on dic but have had my nav lock up several times. I'm thinking my year old battery is getting weak even though it has no problem starting the car.