Technical Immobiliser fault

[Lukedenman]

Afternoon guys and gals

I’ve found this place while searching for info on an issue I’m having with a Punto that’s found it’s way into my ownership. It’s an 08 with the 1.2 8v.

The problem and some history:
This belonged to my SIL who was the second owner and used daily for god knows how many years. She drove it to the supermarket, did her shop and when returning to the car it simply failed to start for her, lights on but nobodies home. No cranking. She had the RAC out who said “ECU fault” and they recovered it to a garage for her who promptly said thanks but no thanks. I agreed to give her scrap value for it and have a go at getting it running.

So, you put the key in, turn to position 2 and the yellow padlock light comes on and stays on. Try and start and you get nothing. ABS and the other “usual” lights come on then go out as you’d expect. If you turn the key quickly before padlock light comes on, there’s a very rapid clicking noise before it gives up and the padlock lights up again.

I’ve searched the forum and worked through all the threads I can find with a similar issue.

As such, to date I have:
Put a known good 3 month old battery on it (came from my running MX5).
Used a jump lead on the negative terminal to a freshly cleaned up earth point.
Checked every fuse in the engine bay box.
Removed the fuse box/BCM and confirmed all 3 plugs are dry and there’s no corrosion.
Fitted a Virgin ECU and paired as per the instructions from the supplier.

To date, everything has resulted in the same symptoms.

Next on my list is to take the key to Timpson to check the chip is broadcasting the signal. Aside from this, I’m fresh out of ideas and I can’t find anything else on here or elsewhere online.

Am I flogging a dead horse or does anyone have any ideas?

 

[RalphM]

No spare key to try?

 

[Lukedenman]

No spare key to try?

Thanks for the reply.
Unfortunately no spare key.
As an aside, I forgot to mention I can hear the fuel pump priming, if that makes any difference.

 

[Ralf S.]

When you say "nothing happens" do you mean nothing happens, or does nothing happen?

i.e. Does the engine crank and turn over as normal? If not, then your starter motor might be knacked.
Immobilsers don't tend to stop the starter cranking - they disable fuel and/or sparks... otherwise your local tea-leaf would just bump-start it to nick it.

If it cranks like a good 'un but just doesn't start.. *and the padlock flashes as you crank*, then it doesn't recognise the key. There is a transponder behind the cowling, that activates and then reads the key signal. Sometimes they have a yellow connector plug.. but I'm not familiar with Punto.
The key is a solid state doodah with a code in it. If you haven't kept it inside your pocket while having an MRI scan or during a "special military operation" near Chernobyl, then it's very unlikely to fail.

If it cranks like a good 'un but just doesn't start.. but there's no visual/warning that anything is amiss, other than the padlock comes on and off at random moments, then it's more likely a "car" problem.. Fuel pump primed is good... but check the injector(s) get a signal while it's cranking and that the coils are live, and the plugs are sparking while it's cranking (just check one.. no need to test all). No joy at one or the other will point you closer to the problem... no joy at either could be a TDC/crank sensor has failed.


Ralf S.

 

[Lukedenman]

When you say "nothing happens" do you mean nothing happens, or does nothing happen?

i.e. Does the engine crank and turn over as normal? If not, then your starter motor might be knacked.
Immobilsers don't tend to stop the starter cranking - they disable fuel and/or sparks... otherwise your local tea-leaf would just bump-start it to nick it.

If it cranks like a good 'un but just doesn't start.. *and the padlock flashes as you crank*, then it doesn't recognise the key. There is a transponder behind the cowling, that activates and then reads the key signal. Sometimes they have a yellow connector plug.. but I'm not familiar with Punto.
The key is a solid state doodah with a code in it. If you haven't kept it inside your pocket while having an MRI scan or during a "special military operation" near Chernobyl, then it's very unlikely to fail.

If it cranks like a good 'un but just doesn't start.. but there's no visual/warning that anything is amiss, other than the padlock comes on and off at random moments, then it's more likely a "car" problem.. Fuel pump primed is good... but check the injector(s) get a signal while it's cranking and that the coils are live, and the plugs are sparking while it's cranking (just check one.. no need to test all). No joy at one or the other will point you closer to the problem... no joy at either could be a TDC/crank sensor has failed.


Ralf S.

Hi Ralf

So, you get the usual system checks with lights coming on then going out when you turn the key to position 2. When you go to turn the car on, the remain lights, including the padlock, remain illuminated, but nothing happens. No cranking, no warnings, no sounds, nothing. I’ve added a link to YT video I’ve just uploaded to demonstrate the problem.

My understanding, albeit through research rather than experience, is that when immob is enabled or the Fiat CODE system has locked/failed, you’d get a similar issue of no cranking. Happy to be corrected on that.

To my knowledge, my SIL doesn’t frequent the Chernobyl area. Worth me checking with her though

Thanks for taking the time to share your thoughts.

L

 

[RalphM]

Difficult to tell but that could be the ignition switch see what others think,

 

[Lukedenman]

Difficult to tell but that could be the ignition switch see what others think,

Thanks Ralph. I’d not considered that. A quick search on here and it appears to be a ring sensor around the ignition barrel that plugs in a little further down the steering column. Does that sound about right?

 

[RalphM]

The ring is the ariel for the immobiliser but they don't usually give trouble, I was thinking
the switch its self as they are very cheap and nasty, about £13 on evil bay you can just change
the switch bit this leaves the key the same it's the bit were the ring plugs into there are depending
on your car 7 or 5 connections some with all big connections some with 1 big and the rest small,
it can be done without taking the lock barrel off the car but you have to make sure know how
it came to bits there are 2 discs that go behind it and are a pain to get back right, as I said see
what others think.
When you turn the key to start position does the instrument panel go blank or is that you turning the key off.

 

[varesecrazy]

Hi

Ive not had the 1.2

But on all other FIATs IVE owned..

The padlock just stops it running.. it will crank no problem

My sons 07 diesel had no slave key..
It was easy to get a replacement as the CODE info was accessed via the OBD port

YES.. the ring aerial is normally clipped around the lock barrel BUT that wont stop it cranking


I had the braided cable on the starter go crusty.. slack the 13 hex nut wriggle the cable and retighten


In your position.. I would get the basics double checked..
then run booster cables from a running car to your
Battery Pos and Engine Neg

Do keep us informed

 

[Lukedenman]

The ring is the ariel for the immobiliser but they don't usually give trouble, I was thinking
the switch its self as they are very cheap and nasty, about £13 on evil bay you can just change
the switch bit this leaves the key the same it's the bit were the ring plugs into there are depending
on your car 7 or 5 connections some with all big connections some with 1 big and the rest small,
it can be done without taking the lock barrel off the car but you have to make sure know how
it came to bits there are 2 discs that go behind it and are a pain to get back right, as I said see
what others think.
When you turn the key to start position does the instrument panel go blank or is that you turning the key off.

Thanks Ralph, really appreciate you taking the time to break this down for me. I’ll start investigating in daylight tomorrow.

I should’ve given some narration in the video as to what I was doing. The instrument panel only goes blank when I turn the ignition off, as you would expect in normal operation.

I’ll let you know how I get on tomorrow. Thanks again, it’s much appreciated.

 

[Lukedenman]

Hi

Ive not had the 1.2

But on all other FIATs IVE owned..

The padlock just stops it running.. it will crank no problem

My sons 07 diesel had no slave key..
It was easy to get a replacement as the CODE info was accessed via the OBD port

YES.. the ring aerial is normally clipped around the lock barrel BUT that wont stop it cranking


I had the braided cable on the starter go crusty.. slack the 13 hex nut wriggle the cable and retighten


In your position.. I would get the basics double checked..
then run booster cables from a running car to your
Battery Pos and Engine Neg

Do keep us informed

That’s some very useful information and it does help diagnostics knowing it should still at very least be cranking.

I’ll check the starter and go over the basics again. I’ve tried re earthing a few times and a fresh battery is currently fitted but I think as you say wise to go over these again. I’ll sling the battery on the optimate overnight and tackle the rest of your suggestions tomorrow. The jump leads to a running vehicle is a good shout that is not considered.

Thanks for the help, appreciate it!

 

[varesecrazy]

Jump leads helps rule out a few poor earths ;-)

 

[Lukedenman]

Yeah I’d tried a jump lead from the negative terminal to a freshly cleaned up area to no avail, but can see your suggestion would be a little more reliable.
Thanks v much!

 

[RalphM]

Make sure you have power to the big terminal on the starter, get someone to
try to turn the key to start see if you get power on the trigger small terminal make
sure its in neutral before doing this. even if the immobilizer is on they usually crank
the fuel pump usually comes on then goes off after a short time

 

[Lukedenman]

Ok, an update.

I left the battery on charge overnight, as previously mentioned this was new for my MX5 a few months ago. That said, that’s another project I’m not using
Freshly charged, we have crank but no start. Although it’s not as straight forward as that.
If I turn the key quickly before the padlock lights up, it will crank until the padlock comes on. If I wait a second with the key at position 2 for the padlock to light up, it won’t crank.

See latest video:


Battery voltage is healthy at 13.7v and the starter is clearly cranking the engine at a sensible rate.

So, progress, but not quite there yet!

 

[eeeno]

Have you run the diagnostics with MULTIECUSCAN (MES) tool? It might need proxy alignment after changing the ECU. However the fault may NOT be with the ECU itself. Was the car badly maintained? Were spark plugs never changed? Then it is very possible that the ignition coil itself has failed. Usually it kills the ECU too with poor spark plugs.

 

[RalphM]

Does it reset the clock when you try to start it?
also if you can prove ownership you can get
a code from a Fiat dealer to start the car in
emergency, though if you have changed the
ecu this may not work or you could try putting
the old one back,

 

[varesecrazy]

RalphM posted this last Summer..
Post #15 may be particularly helpful in your situation..

Panda - Our Panda 6 months on.

RalphM submitted a new vehicle: Our Panda 6 months on. Our Panda Now had it about 6 months and 1100 miles, 22150 miles on the clock, 2006 Panda Multijet , it's suffered a bit from not being used, been garaged from new one owner no real rust just a little light rust on the rear spring cups...

www.fiatforum.com

I only had this happen once.. in a 1985 car.. so just the cranking was patchy ( no immobiliser element to play.up back then..)

The car had high'ish miles.. so I just swapped the disc from a low mileage write.off.. never played.up again

 

[Lukedenman]

Have you run the diagnostics with MULTIECUSCAN (MES) tool? It might need proxy alignment after changing the ECU. However the fault may NOT be with the ECU itself. Was the car badly maintained? Were spark plugs never changed? Then it is very possible that the ignition coil itself has failed. Usually it kills the ECU too with poor spark plugs.

I haven’t got my hands on an MES tool but have scanned with my Autel and Snapon Solus. I’m an IT nerd by trade so I while I do have a reasonable bit of kit, I’m still only a hobbyist.

The car has solid history and comes from family that I trust so when she says it was regularly serviced I’d like to think I can believe her.

I’ve not had a chance to look at the car since last week but I’ll be back on with it tomorrow. I’ll check the condition of the plugs. I was going to pull one anyway as I’d like to know if it’s producing a spark.

Thanks for weighing in, appreciate the help.

 

[Lukedenman]

RalphM posted this last Summer..
Post #15 may be particularly helpful in your situation..

Panda - Our Panda 6 months on.

RalphM submitted a new vehicle: Our Panda 6 months on. Our Panda Now had it about 6 months and 1100 miles, 22150 miles on the clock, 2006 Panda Multijet , it's suffered a bit from not being used, been garaged from new one owner no real rust just a little light rust on the rear spring cups...

www.fiatforum.com

I only had this happen once.. in a 1985 car.. so just the cranking was patchy ( no immobiliser element to play.up back then..)

The car had high'ish miles.. so I just swapped the disc from a low mileage write.off.. never played.up again

Ahhh nice, I hadn’t seen that thread. That’s helpful. Another thing to add to my list of things to check!

Thanks for the link, I’ll hopefully have an update tomorrow!