mjh1

Hello Guys
Need some help
Today I washed the car, took the hard top off, raised the soft top, then family jumped to go for our first every ride with the top down. I started the car put the top down and started to drive away, and the ABS and Battery light came on and the volt gauge was at 16 volts.
Went around the block back home, turn the car off waited few sec and started again, all was back to normal, get going down the raod, and again both lights and 16 volts. Go Back home turn it off wait then back on and lights flicker on and off then stay on and volts back up to 16.
Any ideas? My guess would be the Alternator, but why the ABS light?
99 996 C2 24,000 miles

mjh1

So I go back out and start it again and all is fine, then I give it some gas and the lights come on volt meter acts normal, I turn the air cond and fans on the lights go out, I give it some gas and the light come back on the let off the gas and the light go off, volt meter seems to be working as it should goes up a little with higher rpm's then come back down.
?????

mjh1

Ok, I waited a couple of hours and started the car and everything was back to normal, no lights volt gauge right at 14 volts, took it out for an hour or so drive and all is well.
So now I'm thinking it had to be water from the car wash (hand wash in driveway) that was shorting something?
Any ideas where or how I start looking for what the cause was, anyone had something like this happen to their car? I really don't want to get stuck somewhere the next time it rains. Never had an issue with washing or driving in the rain before.

mpd425

Check the weather stripping in the Frunk to see if water might have gotten into the battery compartment

fpb111

Battery compartment is not sealed. Only the carpeted part is sealed.
There are four drains in there, battery box, to let the water through to the ground. Always good idea to check them to be sure not clogged?

I would suspect soapy water in engine compartment around the alternator. Probably never get it to happen again.

joelpirela

Your Alternator is failing.

mjh1

I cleaned out the front drain plug around the battery earlier this spring (they were not draining), I did look after bringing it back home on the first run and nothing look really wet, some drops of water here and there but no real soaking.
I'II keep my finger crossed on the "Probably never happen again"
Was very disapointing 1st top down ride for the kids told them we were going for ice cream! LOL got two driveways away and turned around! LOL I ended up taking them in the Dodge made them happy, but I was still pouting!

wwest

Your (USELESS!!) volt meter either reads the average voltage or the peak voltage.

What you really need to know, see, is the voltage ripple that results from the regulator/Alternator/Battery voltage regulating PWM dutycycle. Put a few extra milliohms of resistance in the circuit, positive or negative (chassis ground), and the ripple content can get extreme. 16 volts on the "ripple"/waveform high side but 11 volts on the low side (+/- 2.5 volts from the 13.5 nominal) on the low side. Measured at the alternator, NOT the voltage "sink", battery.

The ABS, etc, ECUs "see" that low of 11 volts and "I'm otta here."

Clean and burnish the battery connections and posts and don't forget that chassis ground lug on the negative side. The front to rear electrical connections at the starter solenoid should be checked as should both ends of the engine to chassis ground strap.

Replacing with a new battery often does the trick due to removing and retightening the posts, not the new battery itself.

redridge

do you have issues with taking the key out or have to play around with the ignition?.... if so, might need a new switch.... Im thinking, its prob the car wash. Its good to start the car for a bit after a wash and dry.

mjh1

No issues with the key, drove it around again today for a couple of hours and everything was fine

C4CRNA

My voltage regulator/alternator goes nuts after I wash the car, the needle goes all over the place til it runs for a few minutes.

Zookie

mjh1 same thing just happend to me, im going to give it a few hours, hopefllyu i dont need a $2000 Alternator...

mjh1

Zookie, I have not had it happen again, let me know how you make out and if everything goes back to normal after the water dries up.
I have done some reading here and looks like you can get a rebuilt alternator for a lot less,,,, if that's what you end up needing.

fpb111

I just had to replace the regulator on my Mercedes ML350 -120A Bosch alternator. I was surprised to see it would directly replace the one in my 2003 996 - different P part number same part. There is a DIY on one of the forums that shows three different part numbers that are the same regulator One for Mercedes, one for generic Bosch part number and one Porsche. Regulator replacement DIY for Boxster
http://sites.google.com/site/mikefoc...youralternator

Also Bosch # F 00M 145 225

Zookie

well i had to boost my car this AM. Still getting the Battery Light but no PSM/ABS/BRAKE Light this time. I am geting a Whining noise from the back. Called my shop they said to bring it in to Diagnose. Most likly need a new Alternator...

What a bummer, just did a 1,200 km round trip to Montreal for F1 Weekend and eveything was 100%. Untill i washed my car to get the bugs off... Atleast thank god it happend in my Parking Garage and not out on the Road or middle of nowhere...