Battery light while driving (355)

I went for a drive about 30 miles.
About half way thru noticed the battery light is on ?
So thought crap, backed off put it in a higher gear and thought .......hope I make it home.
Within 3-5 miles light goes out ........
Glitch ? So back on the gas, within a mile or two lights back on.
Did this on/off cycle a couple more times.
Not certain if pushing hard on the gas made it go on or ?
Last 4-5 miles stayed on, was still on when I got home.
Recently moved, and the owners manual is buried somewhere in the garage.
Anybody have a thought, idea, area to look at ?
Had a recent engine out service about 700 miles ago.

 

Intermittent light could be a loose alternator belt, loose cable or an alternator on the last legs. Just stick a multimeter across the batt terminals while the engine is running and check the voltage. Anything over 13.8 is good. If not , you have a problem. The 348 and 355 were notorious for alternator failures due to promixity to the Manifolds and lack of proper heat shields

 

I can help. Of course it is possible the voltage regulator is actually failing, but sometimes not. Here is what I would check first.
1) Make sure you have the updated grounding cable added to your car. Not all cars were updated, and it was not standard until 98 or 99 model years (and even then they can be removed, broken or missing). You can buy the factory part for $20, or simply make your own out of a 12" or so piece of stranded copper wire (use 10 gauge wire) and a couple crimp on ring mounts. One end bolts to the back of the alternator with nut, the other end bolts to a stud on the frame under the car. You can do a search on this site, there are threads discussing this 15 or so years ago with pictures.
2) Another common cause for the light to come on is the signal wire becomes intermittent or breaks completely. Had a friend deal with this for two years, replacing and rebuilding alternators to no end. Finally, it was discovered the little red signal wire was broken. It terminates on the positive cable clamp...but it was originally attached by actually casting the cable into the lead clamp. The red jacket was attached still, but the wire itself was broken. You have to look really closely to find the fault. To fix it they simply took the end of the wire, and spliced on a couple more inches of stranded wire with a ring mount and attached it to the mounting bolt of the clamp. Fixed!
3) The last check (assuming everything else is good), is to suspect a problem with the voltage regulator. You will need a multimeter and confirm you are getting around 14vts while driving. If bad, you can actually replace the voltage regulator with the alternator in place, just jack the car up and take it apart. (not hard) The hardest part to this is sourcing the factory Nippondenso voltage regulator. All the aftermarket ones are garbage from my experience, and a few close friends who also had 355s. Check the threads on 355 alternators, hopefully someone has found a reliable source, but I would NOT recommend wasting your time with parts from Regitar or Transpo. They might work in pinch, for a while...but they will in all likelihood fail.

 

Thanks for the tips, at least now I have a starting point

 

Are you sure it's not the parking brake? The sensor for the handle can cause the light to go on if the handle is not all the way down.

 

Nope that one is on the far left and says brake ..........
Definitely the one with the pic of the battery on the right side
Question, what happens if I drive it like this ?
Will it drain the battery and leave me on the side of the road ?
Stranded, cussing and stomping around cursing the car and the brand.........lol.

 

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Sorry - tired. I read Brake instead of battery.

 

It’s getting late on your side of the country
What will happen if I drive it like this ?

 

Yes, it could leave you stranded if the alternator is indeed not charging the battery. The quick test is to break out the multimeter and see what the voltage is while driving around.

 

I have had regitar parts in m alternator for over 8 years no problems

 

I haven't been able to find a wiring diagram in the F355 Workshop Manual for the alternator. By signal wire, do you mean the wire going to the light? I seem to recall a yell0w-green wire going into the instrument panel to the warning lamp as well as power from the ignition lock going to the other side of the lamp (on a yellow-black wire).

 

Disregard my last post... I found the alternator on the Fuel Ignition/Injection diagram (Fig. 3). A yellow-green wire does indeed go to the light.

 

The signal wire is the small wire connected to the alternator

 

Yes but the red wire that attaches to the positive battery clamp can break and apparently cause the light to illuminate on the dash panel indicating a charging failure. My friend chased this issue for a couple years until someone inspected the battery clamp and noticed the red signal wire is molded into the lead battery clamp. Close inspection showed that while the red wire jacket was still attached to the lead clamp, the copper wire itself was fractured, where it met the clamp, causing an intermittent connection and the reason for the light illuminating.

 

You got some good ones then, I would keep them. My good friend Aeroengineman and I had less than stellar results. I had another friend use them, but forget what exactly happened to him.
Here is my post from Oct 2011: "Some feedback on the Regitar parts...I don't think the quality is very good. Aeroengineman had a bad Regitar voltage regulator right out of the box. After 8k miles of use (about 3.5 years) my Regitar voltage regulator failed today. I reinstalled the used factory Nippondenso voltage regulator and the "batt" light went back out."

 

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So update, just getting to the battery is a pain in the ass ..... lol
12.61 volts - battery voltage with the car off
12.03 volts - engine on all accessories off
11.75 volts - engine on and some accessories on, radio, heater, lights.
So I would assume/guess these voltage readings would indicate a bad alternator ?
Can I drive it without getting stranded, or am I playing Russian roulette with a shotgun ?
Certain the dealer will take me to the cleaners, anybody have a guess on a new/rebuilt alternator (cost) at a dealer.
I can’t get it in until Oct 25th, which is painful...........we have gorgeous weather the next 7 days.

 

Voltage can easily be measured at the terminals in the engine bay (right hand side) under the plastic cover with the "+" on it. Having said that, it's always a good idea to check the wiring on the battery.

If you look at the bottom left hand side of the diagram below you'll see that the alternator feeds power to the car through the battery terminal board in the engine bay (via a large red wire). Make sure that the engine bay lugs are clean and the nuts are tight on the terminals (with the battery in cutout, engine off).

5.2 Ignition/Injection System

How old is the battery? Have you had an engine out recently? Have you disturbed the battery terminals in the passenger footwell (behind the fuse/relay panel)?

 

Thanks for the tip on checking voltage in the back.
I have owned the car almost 5 years so the battery is at least that old plus.
I wanted to check the battery also, cables are short so you can’t pull it out to far.
Battery looks ok, everything tight and no corrosion.

Yes had an engine out a few months back, so everything was probably disturbed.
I will check the other things you mentioned tomorrow.
......and thanks for all the info.

 

I can’t seem to open that link ?

 

Sorry... Some FChatters seems to have problems with my links, others don't. If you like, I can email you the diagram (PM me). It's a lot easier to read than the workshop manuals, but if you have them, the diagrams are in Volume 3, "Wiring diagrams Fig 3" (Bottom L/H and Bottoms R/H)

00500 is the battery
11010 is the passenger footwell battery terminal
11011 is the engine compartment battery terminal
00206 is the alternator
40214 is the cutoff switch
70055 is an earth

The R-25 wire links up the alternator with the engine compartment battery terminal
The R-1.5 wire is the sense line mentioned earlier (the wire goes through pin 9 of a 12 pin connector just aft of the LH rear shock absorber).
The GV-1.5 line from the alternator goes to the battery light.

Try this Motronics 2.7 diagram

2.7 Injection/Ignition

 

Try this... I've squeezed all the relevant bits into the diagram below (excluding the instrument light wiring).

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Bigger diagrams end up being illegible.

 

Awesome, thanks for that

 

Based on your voltage readings, your battery is healthy (for now), but your alternator is suffering from a voltage regulator failure. As I stated before, you could simply just replace the bad voltage regulator and carry on. Assuming mileage is not super high, the bearings, brushes, etc are probably just fine. There are threads here on how to swap out the voltage regulator yourself, without removing the alternator....I've done it, and I'm a literal hack. Try to find on oem Nippondenso voltage regulator. They seem to be more reliable than the aftermarket alternatives.

I would recommend removing the caps on your battery and check the electrolyte level and top up.

BTW, your photo clearly shows the "sense" red wire and how it is molded into the positive battery clamp itself. Yours appears okay. Your voltage readings are all we need to know. Let us know how it goes.

 

Also, make sure your ground wire between the alternator and frame is in place. Again, it was not standard until 98 or 99 and even then, then can be removed or missing. Without it, it can cause charging issues.

I see what appears to be a cable for a battery tender attached to your cable clamps....I would be sure to use it and keep the battery topped up, until the alternator issue is resolved. At the rate your alternator is charging, you were lucky to make it home