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Fiat Punto II Airbag isolation switch fault and its fix

Posted 09-07-2012 at 02:28 by AndyRKett

So.. reoccurring airbag lights have been an issue for the last 4 years on my Mk2b but i've finally got hold of the fix, following a lengthy dispute with fiat over their refusal to sell me the £7.60 part.

Basically my dealership wanted to charge me £50 for a diagnostic plus a further hours labour for fitting this little kit oh and the £7.60 for the part taking the total bill to well over £100, for a fault which was built into the design of the car. (in basic terms they screwed up but wanted me to pay to fix it.)

the 'fix' includes a wiring loom which entirely replaces the wiring between the Airbag isolator switch and the airbag ECU (it is not a simple plug in lead as some would have you believe. what the kit does is give the isolator switch its own dedicated earth which in the standard loom disappears into the dash loom and is shared with other electronic systems. in theory you could achieve the same result by creating your own earth for the switch from the existing loom and a ring connector to ground. (in theory of course)

here's a video explaining the fix

a 'well respected' member on here told me that the fix could be fitted in the time allocated to the diagnostic but either this means that fiat bodge the job and hack the repair badly into place or this was clearly Bull S**T from someone who has no idea, i'm inclined to go with the latter. anyway hope this video is of use

if you have Airbag warning lights following this video explaining whats needed and what you need to do with the Fiat ECU Scan software
Posted in Model Builds, Punto
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Total Comments 4


  1. Old Comment
    T14086's Avatar
    a 'well respected' member on here told me that the fix could be fitted in the time allocated to the diagnostic but either this means that fiat bodge the job and hack the repair badly into place or this was clearly Bull S**T from someone who has no idea, i'm inclined to go with the latter

    That's a bit harsh lol...I believe what was ment was that the labour rate is adjusted and job time, basically this means that the customer gets the job done cheaper...nothing wrong with that is there?
    Posted 09-07-2012 at 21:01 by T14086 T14086 is offline
  2. Old Comment
    AndyRKett's Avatar
    Having now done this fix there are a lot of things that this member has said which don't ring true in respect to this fix, it can be done in the claimed 0.25hrs / 15mins unless it's a real butchers job, you might be able to just about hack it together in about half and hour which would leave the wiring in a potentially dangerous state. to do it safely it really needs an hour plus the diagnostic time in an undiagnosed fault.

    Another thing that was claimed by this member was "The exclusion switch fault is a separate issue related to the design of the switch and the programming in the ECU. Cleaning and tightening terminals can make it less likely to re-occur"

    But the fix addressed an obvious ground noise problem nothing to do with programing or the switch design, if it were a ecu flash or a new switch would be the fix and not giving the switch it's own noise free ground. so it seems this member doesn't understand the fault, and made me wonder if they had ever performed the fix, in any case hopefully this blog post will now dispell all the myths and folk tales that surround this problem so people can be in possession of the facts and not the fiction
    Posted 09-07-2012 at 22:49 by AndyRKett AndyRKett is offline
  3. Old Comment
    First of all you cannot reoccur you can only recur.
    Secondly FIAT will sell you the upgrade kit, 0051786225, providing you insist that you won't try to take it back!
    The you tube clip at
    is very helpful but omits some very important points, from my experience.
    First of all it is not necessary to dismantle the glove box or strip down the loom.
    The first step is to Disconnect the battery!
    Tools required are a T25 Torx head, 10mm open ended spanner or socket, small cheese head(or flat head) screwdriver, 2 flat blade watch screwdrivers and 3 cable ties.
    Using the T25 in the driver's well unscrew the bolt securing a plastic cover alongside the clutch pedal. Ease the cowling away and you will notice that there is a spring clip towards the bulkhead. Using the small screwdriver insert the blade between the metal clip and the base plastic. Press down and turn the blade simultaneously forcing the cowling out. With a torch you should now see a green hinge. Ease this up, or pull it towards the rear of the car and the cable will pop out from the ECU. Repeat the same process on the passenger side. Pull the cable through to the passenger side. Unscrew, and remove, the bolt closest to the bulkhead securing the ECU. Taking hold of the cable you should see two plastic clips either side of the block. Insert the two watch screwdrivers either side. Now use a screw driver to gently push out the cable block. This will reveal the wires. Using one of the watch screwdrivers press down on the pink wire and gently, with your other fingers, ease it up and out of the block. You will need to press twice to get it out. Insert the new wire and replace the cover. Thread it through to the driver's well. The earth eyelet, of the new wire, now needs to be fitted to the bolt you removed. Make sure the eyelet is touching the bulkhead out of the way. Tighten up the bolt.
    Now ease the switch out of its location using the flat blade screwdriver and open the glove box.
    Now thread the other end, of the new cable, up to the glove box, which should now be open. Push it through the hole. Disconnect the old block and replace with the new. Replace the switch and close the glovebox. Using the cable ties secure the new wire to the loom.
    Refit the plastic cowls. If you do not fit the plastic cover on the driver's side, correctly, then there is a good chance that the steering mechanism will catch the plastic!
    Reconnect the battery.
    I used the FIAT EPER UK website to determine my model of car to use the ECU MULTI SCAN software as follows.
    Record the details from your Vin
    The first 9 characters are your Model and the next 8 are your chassis

    Google – FIAT EPER UK

    Spare Parts
    Select Model
    Browse by vehicle data
    Select Model – this is probably the first numerics of your Vin not including the alpha characters
    Chassis # from your vin
    Catalogue – select year from the drop down
    In MVS select your car – 5P= 5 door. Note the string of data. I found that the 60 refers to PUNTO 60 in the ECU Multi Scan options
    Engine Stamp – from your plate on the car
    Version Code - from your plate on the car
    Version – select your model
    Select NEXT
    From the drop down select 555 –Equipment and Electrical Devices
    From the next Drop Down select AIR BAG DEVICES.

    I then followed the instructions in the ECU Multi Scan guide to configure my COM ports.

    I then connected the KKL/VAG lead to both OBDii reader and my laptop.
    The rest is history! Hope this helps.
    Posted 09-02-2014 at 20:10 by Toomyling Toomyling is offline
  4. Old Comment
    J4MALD1N's Avatar


    Does anyone know where to get the wire from as I have an MOT in a couple of weeks and the last thing I want to do is go to a dealership. I'm new to fiat forum so I'm not sure if I'm posting in the right place
    Posted 29-09-2019 at 15:59 by J4MALD1N J4MALD1N is offline