jhardman

Hi all,

Trying to figure out what's wrong...Sometimes when driving, the radio turns off then on. Sometimes this repeats over and over, other times it happens just once. Additionally, sometimes after a drive, the car's power seems to shut down (cannot alarm the car, lock doors; overhead light does not work; car will not start) From there I'll wait a bit (15 minutes or so), power is somehow restored and the car seems to be functioning fine. BTW, the engine has never cut out while driving.

FYI, about 6 months ago the alternator was replaced along with the wire harness and I always use the battery maintainer when not in use.

Any thoughts??

Thanks,

john

kkim

Just curious, why was the harness changed?

jhardman

I replaced the battery (reversed the +/- terminals)...fried the harness. I now know the terminals are different sizes. I'll never make that mistake again...$$$.

NCDan

It sounds to me as if you need to check the major Ground to the car's chassis. It could be lose or maybe a poor contact. Just my 2cents

jnor10

On my previous Porsche (911SC), mine did as you described when the alternator was on its way south. My guess is the radio is very voltage specific, little tolerance for peaks or valleys, so to speak.
Having recently replaced the alternator , you should certainly consider other possibilities, buy I'd at least get a volt-ohm meter on your battery to see what its output is.

Good Luck,

Jeff N.

jhardman

NCDan,

I did a quick check. all looks tight. I'll redue the contacts to see if that makes a difference.

jnor10

I check the voltage. seems to be running 12.4. Im not sure if I was in the correct mode but I had the engine reved to 2k and the 12.4 was virtully unchange. Should I have expected this to run 13-14 range, if the alternator was good?

Another thought I was thinking about was a loose belt...

Thanks for your help!

john

David in LA

It won't be just the harness that was fried - I would not be surprised if the ECU and other electronics (gauges, radio, alarm, etc) were also partially damaged. I would try swapping the radio and the ECU and see if your problems persist.

kkim

John,

The alternator should put out a voltage higher than the static battery voltage when you rev at 2k. Check the battery voltage w/ the car off. It should read about 12-13v. Start the car and rev it (2k should be good) and check the the voltage at the battery again. As you said, if you measure 12.4 w/ no change from the static voltage, I would suspect the alternator as being bad. (check your alt. belt first, though)

A bad alternator may not be your only problem, but it will at least be a start at fixing what's wrong.

jhardman

David,

Thanks for the leads. I did already replace the digital speedo. Where is a reliable place to pick up an ECU (can a used/reconditioned one be trusted?)

kkim,
thanks...the road to recovery continues...

David in LA

Even used ECUs are pricey so I would see if there is one nearby that you can swap temporarily for testing before making the $$$ commitment. Used/reconditioned ECUs are generally OK except you don't always know 100% if they have been reflashed/reprogrammed. Why did you replace the speedo - was it because of damage from the reverse polarity?

jhardman

yes, digital speedo replaced because of bonehead move. ecu was bench tested at the time harness was replaced - was OK then. would it be possible it's not OK now.

thanks for your help on this!

john