Hi Frank here scratching his head
Im at a total loss, if anyone can help please
My daughter owns a 1.4 8V Punto Grande
We have had problems since we bought it last year.
The car at first would either start or was totally dead. It would blow bulbs like they were out of fashion. so i suspected over charging. But this is not the case
when we got it running it was charging nicely with everything turned on.
So got a battery and still the same. So i put a jump lead off the battery to the block. Instant start so replaced the earth from batt to chassis to gearbox. found to be the fault. things were good for a week and it now gives a sudden power fail, loss of everything dash, H lights IGN But it returns as fast as it cut out but with a central locking light showing on the dash. When you re start the car for the next journey the light is off :bang: So i plugged it in to my scanner and there is no power at the OBD2 socket and because of this it just says unable to read. Im worried this will result in an accident. Please can anyone help. We also serviced the car. still does it

Have you checked the fuse box? They get wet and can corrode/cause all sorts of electrical issues

Yes that was done at the start of my search and also all relays were tested off the car & fuses checked. It is dry in there as it goes. everything was replaced with petroleum jell on all terminals. I even cleaned the connections that go into the fuse box and replaced the
+ & - battery terminals just to be sure

Time for some systematic fault finding. If you have no power at the OBD socket, that a good place to start. You hould have grounds on pins 4 and 5 and 12V on pin 16.
With power off check the resistance between pin a and battery negative. It should be less than 2 ohms. Same for pin 5. If this is OK, turn ignition on and check for 12V on pin 16. If this is missing it's time to get the wirin diagrams out and check through. Pick a point about half way (electrically) between socket and battery. If there is voltage there, work towards the socket (agin try about half the remaining distance). If no voltage work towards the battery. When you find the fault, assess it's potential for causing other issues. Have a good look around the area for any other issues.
Get the OBD reader on it and move to the next fault.

Robert G8RPI.

This may sound crazy but recheck your new ground leads.
I had a panda classic which showed similar problems, without the ECU bits clearly.
Turned out to be the ground wire between gearbox and body ground was a little too short , engine movement pulled the crimp lose hence intermittent contact.
This type of wire had terminals at each end and one in middle. Battery one end , gearbox other end, body connection in middle.
I have also had components where the terminal has been crimped on over the insulation ie the insulation wasn't stripped before terminal crimped on.
Hard to see that one.

jackwhoo said:

This may sound crazy but recheck your new ground leads.<SNIP>
I have also had components where the terminal has been crimped on over the insulation ie the insulation wasn't stripped before terminal crimped on.
Hard to see that one.

Click to expand...

Not crazy at all. Surprising how many new parts are wrong.


On connections, I had one years ago with a bare pin type connector (Molex 0.156") where I had voltage on the unit but not on the wire. Nice shiny gold pin, so checked the socket, looked OK but changed the contact anyway. Still no joy. Turned out someone had pulled the unit through the plastic storage bag, rather than cutting the bag open. This had left a thin plastic sheath over the pin.


Got to b logical and systematic and if someone says "it can't be that" check anyway.


Robert G8RPI.

Yes i replaced the earth leads with separate ones. Cleaned all mounting points and checked them after instal. You are right it was the chassis to gear box that was the initial problem to begin with. All earths have been checked now and are good. It was my first stop on the car. Im starting to hate this car to be honest. Its just a living bad display of bad workmanship and poor quality to be honest

Thank you for your input. i will try this as soon as i can get the car home again

Totally understandable you frustrated any normal person would be.

Stay logical , you will get to bottom of this.

Can anyone help with identifying where the wiring loom picks up earth from body please?

Once you have eliminated battery earth leads as problem check the +ve battery lead near and at crimped connections.
Gently pull and bend lead feeling for fracture beneath the insulation.

Check lead fastening at starter motor , it is often at this point the live feed for the other circuits are taken from . Check wires at this connection on the same way.

I think fiat ask a lot from the ignition switch controlling the power for most if not all electrics .
Possibly consider a new switch, though I'm loath to suggest spending money without identifying fault first.

Now for another silly check, I once had a heavy key ring that was able to switch off my ignition. Got rid of that key ring quickly.

Thought that earthing issue was solved ?
It is coming a bit confusing, what is the real problem ?? Car doesn't start (and I hate it) is not a correct answer, you need to be more precise otherwise never will get constructive answers ...
@ Jackwhoo, the "power for most if not all electrics" is provided by a huge relay, the ignition switch is way from being overloaded ! Beside that I fully agree with the heavy key ring : ANY car will suffer from this, aswell as the foot resting on the clutch pedal or the hand on the gear lever !!

BTW, OBD positive is fed thru a fuse in the body computer...

Regards, Bernie

Hi Jackwhoo. Last sentence not as silly as it sounds. There was a thread a few months ago regarding a dead ignition where there was a heavy object on the key ring which may have caused the problem they had. Unfortunately the OP never came back.
Bernie beat me to it, his post beat mine.

did you replace the battery terminals with the type that you strip the insulation off the wire then bare wires are clamped into the terminal with screws?

sorry I was not up to date with this particular model having a huge relay.


thank you I stand corrected.


I should have said some cars rely a lot on the ignition switch, particularly older cars .


Lets give original poster some benefit of doubt and read him as saying he hates not being able to get to bottom of the problem. Feel his pain .
Encourage poster.


I was not having a go at Fiat regarding my heavy key ring it wasn't even a car from Italy.


thanks Arthur, That's funny heavy key ring came up recently , it wasn't me posting about it before.

Bernie
It appears the problem is now the car starts reliably but now cuts out with total electrical failure at random times, but then will restart.

Sure enough those kind of problems are very frustrating and I can understand people willing to throw the sponge...
But Hey ! progress have been made from the original post : the car (seems) to start ok now. The fact that it cuts out shows a potentialy mechanical issue (I mean physical) : lose connection, bad main relay ? broken wire (had that on my ABS main power, sometimes making contact, sometimes not !)?

If it's a TOTAL electrical failure it should not be that hard to find, don't give up !! (and remember to feedback ;-)

Regards, Bernie

This helped me out and the problem has been repaired now and all running sweet. Thank you every one for all your kind help

ff1963 said:

This helped me out and the problem has been repaired now and all running sweet. Thank you every one for all your kind help

Click to expand...

What did it turn out to be in the end, as anyone else who reads this thread might find that snippet of info useful in the future.
ff1963