F355 Alternator Problem returns! Damn!

Have you tried attaching an extra ground strap to it yet?

 

After you try the ground and look at all conections, I would pull the alternator and have it checked. I just did my TR, it was a *****, but I know the 355's are a peice of cake, I helped my friend with his, but again I have a lift at my house, so easy for me to say!! He had all sort of problems like you, he had it rebuild, (like I did ) and it was his internal relay. It cost me $142 to rebuild completly, the dealer wanted $1800.....made me laugh!! His cost was close to mine.

Good luck...Robert

 

Hey Robert, did you get a kit a rebuid it yourself or did you send it out. If you got a kit, I would be interested to know who sells them for the Nippondenso units.

 

Bummer that it was working when you got back home, preventing you from pulling relays to narrow down the problematic circuit area.

Based upon *when* your problem started on this last drive, when it started working again, stoped working, started again...

...I'd take a wild shot in the dark that your ground problem is related to when one of your 3 radiator cooling fans is kicking on...though it's bizarre that a fuse wouldn't just blow and the problem go away (until a new fuse, anyway)...which makes me think that you've got a floating ground...that your chassis itself isn't making a good ground, and may even have a slight voltage.

If that's the case, then adding a 2nd ground strap from your alternator to your chassis may not help much, if any...you'd need to run that 2nd ground strap instead directly to your negative battery terminal (or perhaps just to the common post that you cleaned in the engine compartment).

 

On a 360 Modena I just finished, the car came in with the battery light on and the car dying on the road. I removed the alternator and took it to my local rebuilder (the same one that did the Delco on my Mondial t) and he put it on the bench. Zero, zippo, nada... Instead of rebuilding (which, when you're charging someone to diagnose the problem and do the R&R, entails neccessarily insuring a higher probability of success than the lesser success rate of rebuilds), I bought another from FoW and put it on the car.

Same problem. After tearing what is left of my hair out, I took a 12V test light and placed it on the eyelet connector at the B+ terminal at the alternator. NO JUICE! Then, because there was juice at the other end of the harness at the starter motor, I pierced the insulation of the 4G wire an inch away from the eyelet terminal. Voila! 12 volts. Turns out that the crimped area of the copper, multi-strand wire going into the eyelet terminal was so corroded, broken or otherwise not working, that there was a break in the fundamental alternator-battery connection.

I trimmed back the insulation after cutting off the old eyelet and soldered AND crimped a new copper eyelet connector on. Fixed. Permanently.

Sounds like a good area to look on your F355...

-Peter

 

This may not be a loose wire even though it seems like it. It's the dreaded VR again I think. When they start to go, they work, then fail, then work, then fail...until they just fail. At least that's what mine did. I bet yours is on the same downward spiral.

You need to find what's causing this failure; THAT could be a loose ground wire or bad ground itself. So before you replace the VR, you need to find it or this will happen again. Sorry, but this is a PITA kind of thing...

Ken

 

Good points, Ken.

 

I found my LH fan fuse blown about 6 or 8 weeks ago...and replaced it...never had a charging issue, ever. Fuse has not blown again, and I have been driving in stop and go traffic in the low to upper nineties with no problem. It certainly sounds like a failing voltage regulator though. A friend had a similar problem with his 348, and had trouble diagnosing...it was heat related...voltage would drop after running for 30 minutes...then after a cool down, fine again. Bench testing for a loooong time, would show the problem....they replaced with a factory voltage regulator as that is what my buddy wanted, but did say their is an upgraded or "heavy duty" VR for the ND alternators...I believe it was made domestically in the USA. Call Romain Electric in Kent, WA and maybe they can help you, that is where my buddy took his alternator for diagnosis and repair. http://www.romaineelectric.com/index.html

 

My cooling fan idea was just a shot in the dark, AZ. You drive for so many miles, then the voltage drops, then a little while later everything works again...which might coincide with a water or oil radiator fan leaking current into your chassis to give you a floating ground while the problem fan was receiving power.

But frankly, Dave Handa's heat-related idea has more merit.

No matter, you still want to pull relays when this problem is occurring. If you can make the Alternator light go off, then obviously you've found your problem circuit area...and if not, then you've at least ruled out several sections of your car's overall electrical system as being the problem.

Said problem might be from heat, might not...but it would obviously be good to know the problem area.

 

There are no fused or relayed circuits involved in the connection from alternator/battery. you must check the connections at the distribution block in passenger footwell, follow continuity through battery/ignition switch/relay boards. the wires themselves must be wiggledf and checked, there are problems with many of the terminal/wire continuity.

brian
Autocar Sports, Indy

 

is the alternator warning light coming on bright (like before starting the engine), or is it dimmer?

also, is there a diode in the warning light circuit such that if the B+ voltage is higher than the fusebox voltage, the light won't come on?

is the voltage gradually changing from 13.x to 12 and back, or is it pretty much one or the other?

 

maybe a bad battery?

 

Those are the most likly areas. Now comes the hard question: do you replace the VR again and hope that you caught it? Is it possible to bypass the VR in the alternator and have a heavy duty external one? I could do that easily in mine if I had a mind to.

Ken

 

It is hard to imagine a relay problem or a fuse panel problem that could cause an alternator to have an intermittant output. Since you are monitoring the system voltage by the cigerette lighter and the the dash charging lamp go through several connectors, maybe a wire from the alt. output terminal to a voltmeter in the pass compartment will help with finding out where the intermittant failure is. Please be very careful with the routing and maybe even fuse (one amp) the wire close to the alt. Even though you've done a good job cleaning the contacts on the cables between the alt. and the starter, perhaps the wire is broken/corroded somewhere. You could run new one and of course, disconnect the old one. Everytime a new alt is installed, the output cable is flexed which might explain why is works for a bit and then fails. There may be a terminal block in the engine compartment where the battery cable terminates and then another cable runs to the large starter stud. I'm assuming the battery is in the nose of the car and the cig. lighter is probably feed from there. If any of those cables were intermittant, they could cause the voltage regulator to see an open load and cook itself. So maybe monitoring the starter terminal, then either the alt. output terminal or engine compartment/battery cable terminal depending what happens. Please be very careful with the routing of battery wires because the 120 amps output from the alt or 770 amps from the battery can make things very exciting.....a one amp fuse+holder is easy to solder (very close to the terminal lug) to your sensor wire(remember a ground wire also). And since we are grasping at straws, I wonder what kind of ground cable you have between the engine subframe and the chasis. Lastly, take your old core and have it rebuilt and try to find out as much as you can about it.....will they cook themselves if ran without a load, does the warning lamp provide a bootstrap current to charge, what happens if the warning lamp was shorted to ground, could water get on the alt and short out the diode block, etc. Good luck....you are fighting the good fight!

Jeff Pintler
89 348tb (on the mend), 86 tr (bad clutch master)

 

Check continuity to ground. Take an ohm meter and attach one probe to the battery NEG terminal and check all your ground points. If they are all close to indicating just a few ohms (zero is best) then you've got good grounding.

Also check the grounding straps at both ends, they should be the same. The post above by LOLAMAN, about the failure being within the crimping connection, was pure insight.