355 Alternator Light issues

Triple check the battery "water" and connections, especially the integrity of the positive cable where the small sensing wire attaches to the main terminal.

As difficult as it is to get to the 355 battery, it is very neglected. Just some old fashioned and no longer commonplace maintainence will hopefully do the trick.

JM3

 

Check your battery voltage with the ignition switched off, should be around 12 volts, then check again with engine running at a slightly higher rpm than idle. Voltage should increase to 13 volts or slightly higher. If not, check your alternator output voltage, could be the start of a weak alternator and also check battery fluid with a tester, could be a weak battery and requires changing. If you have a dry battery and the alternator output is ok, it's a bad battery.

 

I had this precise, exact symptom a couple of years back. Turned out to be the "sensor" wire (the one that tells the alternator when to charge and is wired through the dash bulb).

What happened was that the wire had a simple mechanical failiure about 2CM from the socket where it comes out of the back of the alternator. The break was caused by vibration, like if you bend a piece of wire again and again it breaks eventually. The plastic insulation stays intact though, so it can be tricky to find.

Anyhow, the auto electrician fixed it in 10mins flat once he'd found it. Chopped out the bad bit of wire, soldered in a new piece, heatshrink wrap and job done. I stood chatting with him under the car while he fixed it, total cost €50.


Could worth a quick look...

 

Good suggestion I look for atleast +14V at high idle

 

Stupid question I know, but is the belt tight??
Pay attention to the Amps as well as the voltage. It is possible to have 12-13volts but no amps, hence no charging and a warnig lamp.

 

Absolutely, I've had this before. Had 12V no prob but couldn't flow any electrons...

 

Hey AZSpider, in addition to all the excellant advice & suggestions, I would also recommend installing a ground strap from alternator to chassis. This was done by the factory on late 355's (from Assy#32629 onward) and 360's to help alleviate problems believed to be caused by intermittent grounding (or failure of ) between engine & chassis due to dirt & grease, or wires breaking similar to what spaghetti jet described.

 

how do you get to the battery in a 355? when i turn my ignition key all the lights comes on and I can hear the pumps running but my starter does not make a sound. My F1 tranny light will sometimes come on and beep for a split second when I change gears and now my alarm light keeps blinking till I arm/disarm alarm. Is this a battery issue? Does the alarm have it's own battery? Thanks for any help.

 

Search "355 alarm". You will need to replace the rechargeable battery inside the alarm module. Well, that or replace the entire alarm module! Do the search, and you will find all the information on the fix.

Okay saved you some time, here ya go:
http://www.ferrarichat.com/forum/showthread.php?t=132336&highlight=355+alarm

 

As Brian said, look for the ground wire from the alternator to the sump. Looks like this:

http://www.ricambiamerica.com/product_info.php?cPath=2_735&products_id=208383

Of course it is available from Brian as well...

 

Check the plug itself. Remove the rubber insulator from the rear of the plug, and check the solder connections at the termnials. Working further up the harness, slit the shething open and check the wiring comming down to the plug. Very common for the wiring to come apart where it bends down towards the alternator. Usually you will need to replace about six inches of wireing (all 3 wires) to the plug and the plug terminals to fix the problem.