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Old 06-07-2008   #1
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Airbag warning & child seat warning lights on

Hi,

Punto Mk2B, 53 plate.

Last few days I've had an airbag warning light staying on and also child seat warning light staying on (after usual flashing on start-up). I've seen threads regarding airbag warning light, pointing to wiring connector issues (under seat or over glovebox) but haven't checked these out yet. Switching passenger airbag off/on makes no difference to symptoms.

Anyone had similar? (i.e. child seat warning as well).

Aside of the safety issue (presume airbags wouldn't deploy while warning light on), is this an MOT fail? (it's due in couple of weeks).

If it is a connection and I find/fix, does it need ECU reset? Is it same diagnostics connector/equipment as the main ECU or is it different for the airbag system?

Cheers,

Red.
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Old 06-07-2008   #2
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Re: Airbag warning & child seat warning lights on

sounds as if you require wiring loom upgrade (dealer fit only) around 60-70 fitted.
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Old 07-07-2008   #3
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Re: Airbag warning & child seat warning lights on

What's the benefit of a wiring loom upgrade? Is it to eliminate some dodgy connectors? Surely if it's wiring (rather than components like air bags, switches, sensors or ECU) it can be found and fixed with current loom. After all, it was working OK a week ago.

BTW, I had a quick look around the passenger seat and can't see any wires under there. Anyone know whether the mass sensor in the seat is only fitted to some models? There is definitely a passenger airbag and a switch to disable it (when carrying a child in child seat).

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Old 07-07-2008   #4
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Re: Airbag warning & child seat warning lights on

Quote Originally Posted by red View Post
What's the benefit of a wiring loom upgrade? Is it to eliminate some dodgy connectors? Surely if it's wiring (rather than components like air bags, switches, sensors or ECU) it can be found and fixed with current loom. After all, it was working OK a week ago.
Your call, only trying to help.
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Old 12-07-2008   #5
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Re: Airbag warning & child seat warning lights on

T14086,

Sorry, probably conveyed wrong tone (sometimes difficult in writing). I wasn't dismissing your advice but instead trying to understand how the wiring loom mod might fix my problem. I've read elsewhere that there is skant information publicly available on that mod and that it is only entrusted to dealers (on safety grounds).

As for my further investigations, there do not appear to be any wires connected to the seats and no connectors above the glove box. I've had the passenger airbag out and it has a two-pin connector at one end - very robust and secure. I've also had the passenger airbag inhibit switch out; again a two-pin connector that looks fine.

I went next to the airbag ECU (under centre console). This has one 24-way connector but only 10 pins used. I have Haynes for MK2 but as my Punto is a 2B (the upgrade that started late '03) the wiring diagrams are not quite right. Anyway, here's what I've found as connections to the airbag ECU:

1. Black/Violet, earth connection
2. Blue/Red, 12V supply from 7.5A fuse F50
3. White/Green, connected to the "multi-timer unit"
7. Pink/Green, connected to the passenger airbag disable switch (other side of switch is earthed)
9. Violet/Black, to dash, passenger airbag disabled lamp
10. Light Blue/White, to dash, airbag fault lamp
21. Blue, driver airbag
22. Brown/White, driver airbag
23. White/Black, passenger airbag
24. Orange/Black, passenger airbag

Interestingly, the Haynes schematics show that the airbag fault lamp has a pull-down resistor in the dash so that if the airbag ECU is disconnected, the lamp illuminates. Potentially, the lamp could be extinguished by disconnecting the airbag ECU and putting a link between pins 2 and 10 in its loom socket (pulling the fault lamp up to 12V). Haven't tried this and of course couldn't possibly recommend it!

Now, if the fault was transient or fixed by disconnecting and reconnecting plugs, does anyone know whether the red lamp would extinguish? I saw one post by someone who regularly repairs such faults and he said that the light goes out when he fixes the fault but that he plugs an examiner in just to get a printout so that he can get paid. I could do with knowing because if the light won't go out until reset by an examiner, I might have fixed the original problem already (and just need a reset).

There do not appear to be any connections between the airbag ECU and the "main" ECU so I'm guessing that an OBD tester woudn't be any advantage here. If that's the case, does the examiner plug directly into the airbag ECU? Is this examiner a bit of kit that only FIAT dealers have?

red.
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Last edited by red; 12-07-2008 at 21:28.
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Old 17-07-2008   #6
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Re: Airbag warning & child seat warning lights on

Hi red,

Just interested to see if you got any further with this? Sounds similar to my fault.
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Old 18-08-2008   #7
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Re: Airbag warning & child seat warning lights on

I had this problem.
04 Active Sport

I took to the dealer in Milford who fixed it for free, took him about 5 minutes and said he just upgraded the wire.

Common fault?
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Old 18-08-2008   #8
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Re: Airbag warning & child seat warning lights on

Quote Originally Posted by C17MGO View Post

I took to the dealer in Milford who fixed it for free, took him about 5 minutes and said he just upgraded the wire.
Not same fault as mentioned in post #2

I'd be wary of any '5 min fix' on airbag wiring!
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