Hi guys and gals, I have a 2012 fiat punto 1.2 . The battery died on my one. Day. I put a volt meter on the battery after a charge and was getting 12.3v. I have changed the alternator but I am still having the same volts. I have checked the earth's off the battery negative and they look fine. The new alternator is also reading 12. 3 v off the main lead. I know it could be a dodgy alternator from new but I doubt it. What else should I check? Does anyone know where the negative wire on the alternator goes to? I have changed the terminal at the alt end as it looked very worn but bot sure where to find the other end. And if this is faulty will it stop the new alternator giving over 12v
Technical New alternator still not charging.
- Thread starter Aaronlm
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Technical New alternator still not charging.
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Who swapped the alternator? 
Mr. "Who" should be familiar with the charging basics and check the positive wire (if there are any "things" attached or it's just a straight wire from the alternator -> starter -> battery, like most Fiats were wired in the past). Battery to the main fusebox is a different circuit.
If you can't tell if there's a fuse on the main wiring (related to charging), there's no hope for you (too complicated).
"Who" should also know, there's no negative wires to the alternator and starter. Car body, gearbox and engine block acts as a "ground/earth/minus".
Alternator needs an "excitation" to start charging, D+ wire. In theory it should also work by self-excitation above certain speed, RPM, but it's not 100% guaranteed. Line D+ is managed by ECU electronically (and by software tricks). It's a gray/black connector on the side of the ECU (between ECU and battery).
https://aftersales.fiat.com/elearnsections/main.aspx?nodeID=199002598&languageID=2&markID=1&modelID=199000000&valID=199000000&prodID=199000000&modelName=Fiat - 199 - Grande Punto&langDesc=English§ionName=Descrizioni&validityName=1.2 8v
Schematic, wiring diagram: https://aftersales.fiat.com/elearnsections/main.aspx?nodeID=199018275&languageID=2&markID=1&modelID=199000000&valID=199000000&prodID=199000000&modelName=Fiat - 199 - Grande Punto&langDesc=English§ionName=Impianto Elettrico&validityName=1.2 8v&isExaminer=
Fuses/relays in Grande (EVO/2012 is a paid access unfortunately).
https://aftersales.fiat.com/elearnsections/main.aspx?nodeID=199009538&languageID=2&markID=1&modelID=199000000&valID=199000000&prodID=199000000&modelName=Fiat - 199 - Grande Punto&langDesc=English§ionName=Descrizioni&validityName=1.2 8v&isExaminer=
What type of battery terminal clamp (positive) do you have? Simple one (just a clamp) or a mini "fuse box"?
But still, alternator should be unfused (direct connection to the battery).
Mr. "Who" should be familiar with the charging basics and check the positive wire (if there are any "things" attached or it's just a straight wire from the alternator -> starter -> battery, like most Fiats were wired in the past). Battery to the main fusebox is a different circuit.
If you can't tell if there's a fuse on the main wiring (related to charging), there's no hope for you (too complicated).
"Who" should also know, there's no negative wires to the alternator and starter. Car body, gearbox and engine block acts as a "ground/earth/minus".
Alternator needs an "excitation" to start charging, D+ wire. In theory it should also work by self-excitation above certain speed, RPM, but it's not 100% guaranteed. Line D+ is managed by ECU electronically (and by software tricks). It's a gray/black connector on the side of the ECU (between ECU and battery).
https://aftersales.fiat.com/elearnsections/main.aspx?nodeID=199002598&languageID=2&markID=1&modelID=199000000&valID=199000000&prodID=199000000&modelName=Fiat - 199 - Grande Punto&langDesc=English§ionName=Descrizioni&validityName=1.2 8v
Schematic, wiring diagram: https://aftersales.fiat.com/elearnsections/main.aspx?nodeID=199018275&languageID=2&markID=1&modelID=199000000&valID=199000000&prodID=199000000&modelName=Fiat - 199 - Grande Punto&langDesc=English§ionName=Impianto Elettrico&validityName=1.2 8v&isExaminer=
Fuses/relays in Grande (EVO/2012 is a paid access unfortunately).
https://aftersales.fiat.com/elearnsections/main.aspx?nodeID=199009538&languageID=2&markID=1&modelID=199000000&valID=199000000&prodID=199000000&modelName=Fiat - 199 - Grande Punto&langDesc=English§ionName=Descrizioni&validityName=1.2 8v&isExaminer=
What type of battery terminal clamp (positive) do you have? Simple one (just a clamp) or a mini "fuse box"?
But still, alternator should be unfused (direct connection to the battery).
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I fitted the alternator. Sorry if I'm asking silly questions i am a complete amateur but I changed it in the past with no issues so was very confident now im stumped. So is d+ the "negative" on the alternator? The only issue I can see is that this wire is looking a bit worn out. I put a new terminal on the alternator end but not sure where the other end is? Any advise what to look for? I'm confident the battery is fine as it's 2 months old. The positive cable is all good and I'd assume a new alternator is all good .
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Come on, don't be that amateur. Told you, there is no negative wires. No such thing here (alternator and starter). Read again previous post, links.
There is probably a wiring/connection problem somewhere. But it's a simple circuit. TWO wires, big (B+) and small one (D+). That's it.
Even if there is a slightly bad ground at alternator body (dirt), it can't be that bad (resulting in no charging at all) in most cases.
So line D+ is to be inspected (from the alternator, previously mentioned gray connector near ECU, and ECU itself). Ohm-meter, continuity.
Alternator can be excited using small current on D+, for example with small 12V LED indicator/control lamp (you put it between battery Plus and D+ on the alternator = it should "wake up" and start charging, when the engine is spinning of course).
That's all for basic home checks (besides main ground/earth). If D+ line is OK and/or LED trick doesn't work, it's a bad alternator probably (it's dangerous while engine is in operation, but check the voltage at alternator, not only at battery terminals). Or a very dirty job (alternator body is not contacting the engine block, there is so much dirt, grime, oil, rust). If the connections are bad, there is a danger of "frying" the alternator (regulator), but normally it happens when it is charging OK, and you suddenly cut the load completely. Regulator can be shorted and overcharging. But your unit is not even trying to charge...
"Testing" alternator (without load) with the drill can damage it. Don't do it folks. Slow turn by hand is OK (to check the bearings/brushes by feel and ear). Have you "tested" your brand new unit before installation?
PS
Check the Internet, what they say about "new alternator not charging": https://www.google.com/search?q=new+alternator+not+charging+battery
It is a common/universal automotive problem (not brand/model specific at all), go figure.
There is probably a wiring/connection problem somewhere. But it's a simple circuit. TWO wires, big (B+) and small one (D+). That's it.
Even if there is a slightly bad ground at alternator body (dirt), it can't be that bad (resulting in no charging at all) in most cases.
So line D+ is to be inspected (from the alternator, previously mentioned gray connector near ECU, and ECU itself). Ohm-meter, continuity.
Alternator can be excited using small current on D+, for example with small 12V LED indicator/control lamp (you put it between battery Plus and D+ on the alternator = it should "wake up" and start charging, when the engine is spinning of course).
That's all for basic home checks (besides main ground/earth). If D+ line is OK and/or LED trick doesn't work, it's a bad alternator probably (it's dangerous while engine is in operation, but check the voltage at alternator, not only at battery terminals). Or a very dirty job (alternator body is not contacting the engine block, there is so much dirt, grime, oil, rust). If the connections are bad, there is a danger of "frying" the alternator (regulator), but normally it happens when it is charging OK, and you suddenly cut the load completely. Regulator can be shorted and overcharging. But your unit is not even trying to charge...
"Testing" alternator (without load) with the drill can damage it. Don't do it folks. Slow turn by hand is OK (to check the bearings/brushes by feel and ear). Have you "tested" your brand new unit before installation?
PS
Check the Internet, what they say about "new alternator not charging": https://www.google.com/search?q=new+alternator+not+charging+battery
It is a common/universal automotive problem (not brand/model specific at all), go figure.
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