Dash lights and battery issues- 2008 GT

SC300ES

Member
Not sure if this is the right place to post it.

Few days ago my wife told me all the lights on the dash lit up while the engine was running. She drove the next day with no issues. Friday morning the battery was dead.

Today, I replace the battery. Here are the issues:

1) The battery reads about 12v with the engine off. Once I turn the engine on it reads about 17v+. This should be in the 13-14v range.
2) The lights on the dash go on and off. (Traction, BSM, battery, seat belts, and the passenger air bag light by the clock/radio)
3) The window switches work and they don't work. None of the AC buttons work. Radio works and then it has no sound.
4) Tried to drive to a local Autozone to get the codes read. I couldn't make it around the block since the transmission wouldn't engage. It felt like it didn't shift out of first gear even though the dash showed the gear numbers go up. It also made clunking noises when shifted from park to drive or park to reverse.
5) After I came back home. I moved it back and forth and it seemed like it was moving normal.

Any ideas?

Thanks

Ed
 
Well, your vehicle appears to have a voltage regulator that can be replaced if it is bad, but I believe the ECU might also control amount of the output voltage, I don't know how to troubleshoot this but if you can find and download the FSM (factory service manual) there should be a section that explains how to troubleshoot the overcharging issue or someone else might chime-in to help you out with it...

Or I suppose you can find a used voltage regulator (for cheap) from an auto salvage yard and swap it out with yours, it probably would be very easy to swap out (unless it requires removal of the alternator) as it appears it just plugs in to a connector and a couple other electrical connections on or near the alternator.

Anyway, this should be the voltage regulator I was referring to:
http://parts.coxmazda.com/p/Mazda__...ml?partner=googlebase_adwords&kwd=&origin=pla
 
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It is almost certainly your voltage regulator as rsvinylgraphics said above. If it were my car, I would get a remanufactured complete alternator from a reputable source (Denso for example) and replace the whole unit. Rock Auto shows a price of $236.79. I assume since your car is a 2008 that it has 100k+ miles so it would not be worth it to me to just do the regulator. Just my humble opinion. YMMV.
 
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