Power surges (radio turning off, instrument panel flicker, light flick

[swaff]

I am having a weird issue in my 99 911 Carrera where I will lose power momentarily. From time to time, I will see the exterior lights flicker, instrument panel flicker, and if I let it idle for quite a while, sometimes the radio will turn off and back on, then the cruise control light will be on. The exterior lights from time to time will also slightly dim momentarily when I turn on a blinker signal.

I initially thought this might be the alternator. My battery gauge is usually reading 13-14, but when the flicker behins to happen, it looks more like high 12's. A check at the auto store said the alternator was ok (they checked it at the battery with the car running), but when they checked it, I was not noticing any flickers.

Tonight, I pulled in somewhere, and was on a call through the radio via Bluetooth. I turned the ignition far left, to turn off the engine, but left the key in so my radio would stay on and I could stay on the call. After a few minutes, with the car not even running, it did it....radio turned off and the illuminated instrument panel went dark and then back on. So that rules out the alternator since the car wasn't even running, right?

Any ideas as to what I should look into? I changed the ignition switch to a new one (switch only, not the updated key cylinder/tumbler) back in August, but have read some people saying weird stuff happening could be the ignition. Anyone with thoughts?

Thank you!

Swaff

Edited April 3, 2014 by swaff

[swaff]

Also, I'm not sure if this changes thoughts, but I wanted to mention I have an aftermarket radio and a power amp that powers a sub. The flicker will still happen sometime even if I have the stereo powered off.

Swaff

[Loren]

:welcome:

Are you sure the ignition switch did not have a wire come loose when re-installing?

Have you checked the battery for both specific gravity and load testing?

Does this only happen when the lights are on?

[swaff]

Hi Loren,

I don't think a wire was loose when I reinstalled the electrical portion of the starter. I did that last August and have since driven the car 25k miles with no issues. I took the car to get the battery tested and attached are pictures of the readout. I do not think I had the lights on when I had the power dropout on my radio/instrument panel with the car off, but ignition left in the "on" position. The most baffling part was the dropout with the car not running.

Why does the reading say "Good battery," but the "Battery Health" is rather low?

Swaff

Edited April 3, 2014 by swaff

[swaff]

When taking the car to 2 different shops, I was unable while there to get the car to have the dropout at either place, but I was able to catch a video of the problem at an earlier time:

http://www.swaffproductions.com/porsche/PorscheFlicker.MOV

You'll see the dash lights flicker a little, and then the dropout happens.

Swaff

[swaff]

Anyone?

[Ahsai]

Have you checked if the battery ground cable and engine ground cable are tight and without corrosion? Maybe replace the ignition switch again? These problems happened (much) after the ignition switch change, right?

Edited May 18, 2014 by Ahsai

[Ahsai]

Also, you may want to cut the power (fuses) to the aftermarket components and drive the car for a few days to retest, just to eliminate them as the source of your problem.

How old is your battery? Your battery is ok but not great. It has lost 10%+ its designed capacity. My experience is a new battery usually measures higher than its CCA spec, then after a few yrs it will lose a can be a few %. My 2 yr old 700 CCA battery still measures 680. My car is a DD so it's quite battery friendly though.

Edited May 18, 2014 by Ahsai

[danstellmacher]

Hi

 

Did this fault get sorted?  If so, can someone let me know how.  I have pretty much the same symptoms on a 2003 996.

 

Dan

[swaff]

The fault ended up being resolved after changing out the ground cable at the battery.  The problem was intermittent, but finally I was able to run some tests while the symptoms were occurring, and a voltage drop test from the battery ground post to the other end of the ground cable was showing there to be as much as a 1.21 volt drop with many other significant drops along the way.

 

To try the test on your own, with the car acting up, get a multimeter and touch the black probe directly to the battery's negative ground post and touch the red probe to the other end of the ground cable that connects it to the chassis.  Be sure to touch the black probe to the ground cable's metal end and not the bolt or post that secures it to the chassis.  You can then monitor and see if there are any voltage drops.  You shouldn't see any drops more than 0.5 volts.

 

Much thanks to Ahsai for his extensive help on tracking down and solving this problem!

Swaff

[Ahsai]

Great news and I'm glad it's something that simple!  :clapping: