Technical Battery light

[Fcat]

Hey everyone

Don't know if anyone has any ideas but our 1.2 lounge had an alternator issue with battery light, heavy steering etc. but we limped it home.

I have since checked and changed the battery for a known good one (both test fine on my battery conditioner), I changed the serpentine belt and just for fun, I swapped the alternator for a new one (lots of fun!).

Now every second time we start the car, it is fine with no issues, the other times, it starts with a battery light (heavy steering etc.). I can also read the trouble codes with my trusty Topdon and it says alternator issue and if I reset the code with the engine running, the battery light goes out and the car starts charging.

It's the precise nature of the fault that is confusing me, I've left it for a minute, an hour and overnight and it's always the second start that is perfectly fine.

I'm more of a nuts and bolts guy so the remaining potential electrical confusion is beyond me.

Any clues?

 

[John202020]

I'm tempted to say brand new battery regardless
New engine earth strap if it's not been replaced a requirement at 8 years old or older
Check the wires to the alternator, not the chunky one but the control wires
When starting turn on ignition but don't crank, wait 5 seconds then crank

 

[Mike1alike]

Yes, make sure alternator cables are clean (cable contacts - no oxidation) and firmly connected.
The ground cable is top on the list next. Do a load voltage drop test for both positive and negative lines.

 

[Fcat]

I'm tempted to say brand new battery regardless
New engine earth strap if it's not been replaced a requirement at 8 years old or older
Check the wires to the alternator, not the chunky one but the control wires
When starting turn on ignition but don't crank, wait 5 seconds then crank

Thanks, I'll work my way through this in order of cost and see where it gets me.

 

[Fcat]

Yes, make sure alternator cables are clean (cable contacts - no oxidation) and firmly connected.
The ground cable is top on the list next. Do a load voltage drop test for both positive and negative lines.

Thanks, the 'exciter' wire on the alternator was a bolt on the old alternator and is now a little spade type connector which doesn't seem ideal.

 

[GettinBetter]

Just a couple of questions:

• Does it have stop/start?
• What are the exact specs of the replace battery, (in terms of Cold Cranking Capacity (CCA) or and ISO EC DIN capacity numbers)?
• What does the Negative terminal look like?
• Have you ever changed the earth strap (i.e. the chassis to the gearbox one)?
• Have you got MultiECUScan (MES) software?

 

[Fcat]

Just a couple of questions:

• Does it have stop/start?
• What are the exact specs of the replace battery, (in terms of Cold Cranking Capacity (CCA) or and ISO EC DIN capacity numbers)?
• What does the Negative terminal look like?
• Have you ever changed the earth strap (i.e. the chassis to the gearbox one)?
• Have you got MultiECUScan (MES) software?

Yes to SS but it doesn't work due to a fault with neutral switch (hasn't worked since we bought the car)
Will check it tomorrow but currently has my 'spare' on it which is a higher CCA etc.
Terminals are very clean (both)
Didn't know about the Chassis to gearbox earth will check that tomorrow too, battery earth strap cleaned and multimetered good
I've got a Topdon (Artidiag 500) diagnostic tool which is great, seems to talk fine to the Fiat as well as my 1999 Skoda pickup and my JDM Nissan which has it's own protocol.
Thanks

 

[GettinBetter]

Yes to SS but it doesn't work due to a fault with neutral switch (hasn't worked since we bought the car)

The SS when working properly, is the first thing to stop when things are beginning to go wrong, so it acts as a guide to the overal condition of your car.

Will check it tomorrow but currently has my 'spare' on it which is a higher CCA etc.

Ok, need numbers...

Terminals are very clean (both)

Not what I meant, I was trying to acertain whether it was an intelligent alternator or not. has the negtive ternminal got another small two wired plug attached?

Didn't know about the Chassis to gearbox earth will check that tomorrow too, battery earth strap cleaned and multimetered good

You can't 'meter' an earth strap, least not with a standard DMM. The cable could be connected by a single strand of the earth cable and a DMM would still register continuity.

I've got a Topdon (Artidiag 500) diagnostic tool which is great, seems to talk fine to the Fiat as well as my 1999 Skoda pickup and my JDM Nissan which has it's own protocol.

I assume it does Proxi Alignment, and allows you to reset various items in the \fiat?

MES has the following Engine ECU adjustment option, not relevant if you don't have an intelligent alternator, but shows the complexity of MES.
Replacement of Intelligent Alternator (IAM)
This procedure must be performed when the Intelligent alternator (IAM) is replaced. It will reset the cumulative overtemperature presence counter on the intelligent alternator (IAM). The engine should be OFF when running this procedure.

 

[Fcat]

OK
Topdon says SS issue is the neutral switch but open to alternative ideas
Battery is 65Ah and 600CCA
Battery Earth does have a two wire plug attached - I did wonder what that was for. The alternator only has the 'old school' big live and small exciter connections, can it still be smart?
Internet let me down with resistance test there then
Not sure about Proxi Alignment, but I can interrogate systems like throttle position etc. and read/clear DTC

I am doubting the health of my 'good' battery now as it starts the car fine but is only showing 11.8v

 

[Mike1alike]

I am doubting the health of my 'good' battery now as it starts the car fine but is only showing 11.8v

11.8 V means it's completely discharged. Its health may be just ok, but it definitely needs charging otherwise the health will plunge down very quickly. Do you have a charger for it?

 

[Fcat]

11.8 V means it's completely discharged. Its health may be just ok, but it definitely needs charging otherwise the health will plunge down very quickly. Do you have a charger for it?

Thanks Mike, I think it is just discharged because of all the test start shenanigans but because my wife is on call at night I am firing the parts cannon at the car so it gets a new battery tomorrow to go with it's new alternator and new earth straps. Plus everything gets a degrease/de-rust and general clean whist its in pieces

 

[The Panda Nut]

Sounds like it could be that sensor for the smart charging which I am suspecting it has. Imrpoper detection of battery stae resulting in odd behaviour. If you have a new spade connector on an alternator wire I would solder this on and make really sure its a sound connection. As a matter of course chnage the charge circuit fuse. I once had a faulty fuse cause almost identical symptoms. I was just about to rip the wiring out when an old engineer said change the fuse first. Id never before or since heard of a faulty fuse, but it was.

 

[Mike1alike]

Sounds like it could be that sensor for the smart charging which I am suspecting it has.

I don't think it has smart charging.

 

[Fcat]

Thanks, might as well throw a fuse in the mix. The curious thing is the alternating nature of the fault, its 100% consistent and if on what will be a 'bad' start (battery light stays on), I can clear the fault before start and battery light will extinguish on start! Ironically, I bought a car of this age because its suppposed to be simple and I could do things on it myself

 

[GettinBetter]

OK
Topdon says SS issue is the neutral switch but open to alternative ideas

I know nothing about the neutral switch, where is it?
Does this seem like it?

Battery is 65Ah and 600CCA

Battery is certainly good enough for the vehicle with SS. Mine is 60Ah and 680A CCA which is about as high as you can get and still fit in the battery compartment.

Battery Earth does have a two wire plug attached - I did wonder what that was for. The alternator only has the 'old school' big live and small exciter connections, can it still be smart?

It sounds like it, but to be sure can you get an oscilloscope option on your software? and connect to the thin wire on the alternator, if you get a
wave like the pic below, it's an intelligent alternator

... and the 'exciter' is NOT and exciter in the traditional sense, but a LIN signal from the Engine ECU.

Internet let me down with resistance test there then

The issue, is measuring a low resistance value using the low current of a DMM. If you are only passing a small current through the corrosion/oxide/etc, then the voltage drop will be almost non existent, but trying to pass a large current through the same resistance will cause a voltage drop (depending on the resistance value) of anything up to 12V. You see this when you turn the key and the lights on the dash dim or go out, but battery is new. Typical of a bad earth path. As you probably know, you can test this by adding an alternative earth path (such as a jump lead) from the neg terminal to a good clean engine part (and it costs nothing).

Not sure about Proxi Alignment, but I can interrogate systems like throttle position etc. and read/clear DTC

Ok. But if you own a 500, you'll be better off with MES, not just for this issue, but for all the other things it can do. There is a free version that you can explore and do simulations with.

I am doubting the health of my 'good' battery now as it starts the car fine but is only showing 11.8v

As has been said by others, 11.8V is a flat battery. if it's still starting the car, I would verify the reading, using another meter.

Post back with your plan of action, it's all very interesting.

 

[John202020]

Try one of these? £73 delivered

Exide 027 EFB Car Battery 60Ah EL600

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[Fcat]

I know nothing about the neutral switch, where is it?
Does this seem like it?


Battery is certainly good enough for the vehicle with SS. Mine is 60Ah and 680A CCA which is about as high as you can get and still fit in the battery compartment.


It sounds like it, but to be sure can you get an oscilloscope option on your software? and connect to the thin wire on the alternator, if you get a
wave like the pic below, it's an intelligent alternator
View attachment 481977
... and the 'exciter' is NOT and exciter in the traditional sense, but a LIN signal from the Engine ECU.



The issue, is measuring a low resistance value using the low current of a DMM. If you are only passing a small current through the corrosion/oxide/etc, then the voltage drop will be almost non existent, but trying to pass a large current through the same resistance will cause a voltage drop (depending on the resistance value) of anything up to 12V. You see this when you turn the key and the lights on the dash dim or go out, but battery is new. Typical of a bad earth path. As you probably know, you can test this by adding an alternative earth path (such as a jump lead) from the neg terminal to a good clean engine part (and it costs nothing).


Ok. But if you own a 500, you'll be better off with MES, not just for this issue, but for all the other things it can do. There is a free version that you can explore and do simulations with.


As has been said by others, 11.8V is a flat battery. if it's still starting the car, I would verify the reading, using another meter.

Post back with your plan of action, it's all very interesting.

The neutral switch is behind the trim under the gearstick, there is a lot of associated trim removal to get to it so I guess that is one reason previous owner didn't get it sorted.

After the new battery is fitted tomorrow, if it doesn't resolve the alternate starting we will just live with it for a bit. The good bit is that I have new earth straps and the car is in better shape than it was before I started - including a full cat back exhaust as this was in poor shape and didn't like being uncoupled to facilitate alternator removal.

so, battery fitted and no change to the weird starting procedure, but, the car was noticeably more powerful. It usually struggles up a long hill near our house and regularly need to downshift, now it accelerates all the way up!

*** Breaking news, it IS a smart alternator. I don't want to change it again any time soon as that was an unpleasant experience but perhaps can find a workaround - or just put up with starting it twice every time