Saab 9-7x Aero Flickering Lighting

[tstep]

I have a stock 2009 9-7x Aero. Other than cosmetics, it is more or less a Trailblazers SS.

Very recently noticed that the dash lighting is flickering/strobing ever so slightly, but enough to draw your attention at night. Also noticed the dome light will do the same. Headlights slightly as well.

This is semi-random and does not occur 100% of the time. About the only common connection so far is when the dash battery gauge shows reading a higher voltage than nominal, the flickering will occur.

When it does occur, it occurs at idle, full throttle, and everything in between. I have tried all accessories, headlights, etc on and off to load/unload electrical system with no difference.

Around the web, I've come across a few discussions speculating bad alternator, substandard alternator output, substandard voltage regulator in alternator, headlamp relay, inadequate diameter battery/grounding wiring, bad ground within the electrical system, etc. However, nothing definitive, only speculation.

Any thoughts or experiences?

 

[Gimpy1]

My wife's 2008 New Beetle had an issue with the dash when the intermittent wipers where turned on, the dash would flicker. It turns out that VW didn't ground the dash properly and issued a TSB. Do you have or can you get a wiring diagram? Check all your grounds and make sure the battery terminals are clean and tight. It wouldnt hurt to check all your fuses and relays to make sure they are properly seated.

 

[tstep]

So far checked the obvious grounding locations, but not the via a wiring diagram. Battery seems ok. Acts like very coarse voltage regulation.

 

[BrocLuno]

Run a new #4 welding cable wire lead from the battery Neg (-) to the engine block and on to the firewall. Crimp and solder the lugs that you use for which ever bolts are appropriate. On my Saab 9-5 it was a bolt at the end of the cylinder hear that held a heater hose clamp/bracket. Does not matter, but closer to the alternator the better. In my case the head was the same piece that the alternator mount bolted to. Back off and re-tighten the alternator mount bolts to establish new contact surfaces.

This is a common symptom of the built-in regulator not seeing actual ground ( 0 reference), so it charges at an above normal rate and varies based on the current flow through the various corroded ground contact points. A solid ground that gives the same reference 0 voltage to all sensors including the voltage regulator is the best solution.

It has enough years and wet dry winter summer cycles that the grounds are not 100% anymore ... The factory crimp only connections now have crevice corrosion between the cable, wire and the lugs; and between the lugs and the engine/body bolts.

 

[14Accent]

Sounds like a rectifier dying. It's the world's easiest alternator to replace, I would try it.

Also: YOU HAVE A 9-7x AERO!!! One of, if not THE coolest orphan child of all GM's crazy concoctions. What a sweet ride. Want to sell it? Ha.

 

[clinebarger]

Like 14accent stated........Bad/dying diode in the bridge rectifier. If you put a graphing multimeter to the alternator charge post you would see the AC Ripple.

 

[tstep]

Thanks for the advice. Great place to start. Going to try rewiring the ground first. Don't have a graphing multimeter, but I'll find someone that does.