Some of these details may well be of no help whatsoever, but I'd rather include them in case they help point to some connector, wire or component fault to someone who knows better than I.

This post is just how this fault started for the first time. The next post is what I have done so far and how the faults manifest themselves.

The other day I took a 10 minute drive at night and after 5 mins all sorts of whacky poop started goin' on ;-

1. My connect nav display went dark and all the orange back lights went out like the unit was off yet it was still playing the CD.

2. Then the alternator fail symbol and warning came up on the dash.

3. Shortly after that the ASR, EBD, ABS & an engine fault symbols and messages came up and amongst this the power steering was dropping on and off intermittently, but no symbol or message came up about the power steering.

4. I fully charged the battery for the trip back, but that didn't help anything. On the short trip back, the alt. fail did come and go randomly as I was braking or sometimes when I was slightly accelerating and powering steering kept coming and going as well but still no warning for it.

The car ran perfectly fine for a 30 minute round trip the day before this happened.

So I read up on a lot of the alternator failures on here (unfortunately I couldn't find any posts about an overcharging alternator) and set about my car with a multimeter today, here are my results;-

1. The battery had settled at 12.71v having been taken off charge 36 hours before all this testing.

2. It dropped to 12.45v immediately after connecting the +ve & -ve to the battery. After 2 mins it had dropped to 12.29v and after 55 mins while I was testing with the multimeter it had dropped to 12.05v (the ignition wasn't switched on during any of this, I just hooked up the battery and stayed in the engine bay testing connections).

3. Because of the voltage drop, I checked the current draw and it fluctuated between 5.2-5.55 Amps when the connection was first made then it settled at 3.00 Amps. This seems way too high given that they keys weren't even in it, everything was off.

**2 & 3 could well be down to a slow drain I've had since I got the car which has required me to recharge the battery once a month or every 2 months. The constant draining and charging could have shortened the life of my battery which could be tricking my alternator into overcharging. Tomorrow I am going to hook up a back up battery which is definitely healthy in order to see if it's a duff battery tricking the alternator.**

4. The car starts strong, the +ve to the started solenoid and the main earth cables to the body and engine are solid and have good continuity. The short, heavy red cable from the alternator (A10B I think) to the starter solenoid has good continuity as does A10A - D4 pin A6 according to a post by Deckchair5 about someone else's alternator problems. So as far as I know, all the wires directly linked to the alternator seem to be fine.

5. When the engine is running, the Alternator is pumping out 16.69v at tick-over whether the failure light is on or off and climbs up to and levels off at 17.3v when it's revved (it did seem to pause and try to hold at around 14.5v for a few seconds, but then it just kept on climbing to 17.3v).

6. I would start up the engine one time and the Alt. Fail WOULDN'T come on until the car was revved just slightly and would then disappear when the revs dropped back down to tick over. The next time I would start it, the Alt. Fail WAS on right away and only disappeared when it was revved anywhere up to 1750 rpm and would come back on when the revs dropped back to tick-over. I couldn't fathom it at all.

7. I don't know if this matters or is related, but while I was making notes of my results I saw my climate control bars increasing the fan speed on its own while the engine was running (it wasn't just the display freaking out, I could hear the fan building up). I'm not sure if that is because the engine was running and some of these components were getting the 16.69v from tick-over, but I might as well mention it in case it does matter.


I'm not looking for help just now on points 2 & 3 about the slow drain issue, I only included that in case it might have contributed to weakening my battery and then if a whacky battery can ever cause an alternator to overcharge.

Well thats everything I've done so far. I will try to hook up MES tomorrow and get the actual fault codes. But I would really appreciate any help or advice on the information I've given so far.

16.5v is too high you risk balooning your battery and boil the fluid and possibly making it go bang

Get it sorted, wouldnt surprise me if the battery is toast too...

Ziggy

The car has only been running for 20 minutes total since I started getting the Alt. Failure warning.

There is nothing I want more than to get it sorted, I am not using my car at all until I resolve this so I do need some help tracking down any likely source of the problem.

Ok, I "borrowed" an identical battery to mine from my mums 1.9 doblo just for testing. This did seem to help at tick over, the voltage slowed down and stayed around 14.4-14.6v a lot longer than just the few seconds that it did before, but it was still gradually climbing and it eventually leveled of at 15.2v at tick over. So it did drop by about 1/1.5 volts with a truly healthy battery. However, once my stilo was revved in the slightest, the volts quickly ran back up to the 16ish volts that I was getting before. I am pretty sure my battery is not the cause of this overcharging problem.

I have the fault codes, but I don't think they will be useful as they are just mainly down to the whole electrical system getting too much voltage running through it. If they could help diagnose this problem then please let me know and I will run up the list of all of them.

The only thing I couldn't check out were my Xenon Headlights, I couldn't connect to them. I can't remember if I ever have been able to or not though. I may not have the correct "1/green (or pin 12)" adapter lead.

Is there any loose or broken connection anywhere in the cars electrical system that would still keep the alternator working, but make it produce too high a voltage?

Okay, it's been a week of silence on this so far. Can nobody help me with this overcharging alternator problem?

If it can ONLY be the alternator at fault, thats fine, I'd order one and get it fitted or fit it myself. I really don't want to buy a new or reconditioned alternator only to find that it still over charges & kills my battery and brings up all these errors.

Given that the alternator is overcharging, does that in itself mean the problem solely lies in the alternators built in electrics/regulators OR with our highly electrical gadget'd, gizmo'd and ECU'd stilos, could the problem be external to the alternator like a verdigrised connection block, earth, chaffed wire or anything like that?

Please help if you can, if you can't, do you know someone you could put me in contact with who could help diagnose this? I really can't afford to do it the "garage way" of just replacing expensive parts until it's fixed (assuming it is a part at fault in the first place).

Alternator has builtin voltage regulator, the 3 amp draw sounds like something has shorted and battery positive is going to the rotor coil, which in turn causes the alternator to produce too much current, which in turn causes to voltage to rise.

Get another alternator or replace the voltage regulator and/or the rectifier bridge inside the alternator (depends on setup).

Another possibility is that your exciter (charge/idiot light on older vehicles) is shorted and supplying the current to the alternator exciter circuit, but the circuit should be supplied via ignition lock so there shouldnt be current when ignition is off.
Easy to measure if you got DC clamp meter (like I do, no need to unbolt wires) and access to the alternator back.
If the exciter wire is having current going in it when ignition is off, its the idiotlight circuit (in some cases you can disconnect it and just rev the engine to 4000-some RPM so the alternator self excites, then the vreg takes over and controls the current going into the rotor).
If the battery cable on back of the alternator is flowing the current, its the vreg/rectifier.

3amp might be on the safe side to use normal multimeter and putting it in between the wires and alternator in 10A mode (ignition off).

:yeahthat:

Need a new alternator, soonest.

Okay, well I haven't got around to this yet. Other stuff's been getting in the way and I've been waiting for some decent weather (ha yeah right, shoulda known that'd be too much to expect) so I could do this without crawling around in the dirt, mud n rain. Well I've given up waiting now and I'm gonna take it to a garage to get the alternator out.

Davren, if your around could you help me find out what amperage alternator I should have fitted? I can't remember what number you need to help with this, vin, chassis or engine?

If I have the correct amperage alternator fitted, I'll just take mine to an auto electrician and have him re-wind it or replace the diode/regulator pack which ever it needs. If I have a smaller alternator than I should, I will take the opportunity to upgrade to a higher amp one and buy a replacement.

When all is done I will post on here detailing what was wrong with my alternator to hopefully help others, I hate when a thread is left unresolved by the OP.

Stilo Nutter said:

Davren, if your around could you help me find out what amperage alternator I should have fitted? I can't remember what number you need to help with this, vin, chassis or engine?

Click to expand...

According to your VIN, you should have a 90 Amp alternator (Fiat part number 46774430) if you don't have air conditioning, or a 105 Amp (46782213) if you have A/c.

Either of these part numbers can be replaced with the 120 Amp alternator (46809068) but it's physically larger and more difficult to get past the driveshaft to fit. I posted some information about fitting the larger alternator in posts 12 and 14 of this thread: https://www.fiatforum.com/stilo/340172-generator-stilo-1-9-jtd-115ps-mw.html

Whichever alternator you fit, be carefull not to loose the steel spacer in the aluminium mounting bracket. It can easily fall out and go unnoticed.
.

Davren said:

According to your VIN, you should have a 90 Amp alternator (Fiat part number 46774430) if you don't have air conditioning, or a 105 Amp (46782213) if you have A/c.

Click to expand...

Thanks Davren. I wasn't going to nag you, I didn't send you a reminder to try and give you a couple days to settle after getting back.

I do have the Dual Zone Climate Control, so it should be the 105amp I have. I'll have to wait and see what the garage tells me when they get it out.

I had seen that thread before, but I was looking for it again to refresh myself with it. Cheers.

On a different subject, are you able to tell what accessory packages and optional extras were originally fitted to a certain car given its VIN?

Stilo Nutter said:

On a different subject, are you able to tell what accessory packages and optional extras were originally fitted to a certain car given its VIN?

Click to expand...

Unfortunately not. For the current production models it shows every optional extra fitted to a VIN, but not for the older cars.
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Ok, I finally got this sorted. I decided to take my car to a small local garage to do this as it would have been far too much hassle for me to do crawling in the dirt and I may well have gotten stuck at getting the exhaust flexi section out.

Turns out my alternator was fried, it had a dead short I believe. I'm guessing one of the coil windings corroded free and was touching the casing.

I'm glad I took it to a garage because of the exhaust section I mentioned and him having a pit made it all that much easier. I was allowed in to lend a hand and offer suggestions when he was having trouble so I was directly involved (if I can't do a job myself on my car, then I do like to be involved and know what exactly is being done be someone else.)

He was struggling to even get to the alternators top mounting bolt, but he was trying to reach it from underneath. I saw where he was trying to get to and told him that from the top of the engine/under the bonnet, you would have plenty of room to get to the bolt if the big loom to the main ECU was moved out of the way. He came out of the pit and agreed with me, he then unbolted a small metal bracket that holds the loom in place and had plenty of room (well, you know what I mean) to get a ratchet with a breaker bar onto to top mounting bolt.
Just a tip for if anyone else needs the alternator out. I'm not sure if this is already common knowledge or not, but oh well.

That was the only thing that slowed him down really and he still had the old alternator out in an hour and when my new alternator arrived a couple days later, it was only an hour to put the new one in with a new belt.

The car is running great again. I'm glad to have it back. I have now fitted an LED voltage display in one of the ashtray ....um slots....recess thingys so I can keep an easy eye on the voltage my new alternator is putting out.

On a separate, but related note - Since I have had this job done, my Connect Nav no longer asks me for my radio code anymore. Ever since I bought the car back in Nov 2010, I have never been able to get full access and use out of my Nav because as soon as the ignition was on, it would ask for the code which I didn't know. But now either a new alternator or the fact that I literally had the battery disconnected for 2/3 months has fixed me needing my radio code.

If it's the battery disconnected, then I wonder if the Nav's got a sort of reset by being disconnect from power for so long.

If it's fixed because of the new alternator, then that means it was acting up for all those YEARS because of the old alternator and yet it only started chucking out too many volts recently.
I'm not sure what to make of this, if it was the old alternator messing up the Nav for so long, why has it not been overcharging and whacking out so much more voltage as to cause loads of warnings for the whole time? Can an alternator be slightly gone enough to still kinda work until the day it goes completely?

Or I wonder if Nav got a reset when it was getting the higher fluctuating voltage.

I don't know either way, but I'm over the moon it's sorted what ever the reason. I have finally managed to set the time and turn of that damn automatic locking when going over a certain speed.

the original units are linked to the ecu, so if you remove the stereo it will still work without code when put back. If you put a new stereo in then the new one will be linked and the old one forgotten.
What i suspect is your can network was not operating correctly and this was one of the things it load shed to keep running, now your voltage has returned to the correct levels its brought that part back into use so the stereo is now recognised again on the network - thus no code asked as the car recognises it.
Thats what i suspect is happening anyways.