Author Topic: seat belt pre tensioner light on  (Read 533 times)

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cc

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seat belt pre tensioner light on
« on: February 07, 2019, 10:24:05 AM »
Hi guys
The light is on for a fault on the seat belt pre tensioner on the blue 2002 156.
Anyone know why they come on? Is it common and usually a poor electrical connector?
cheers CC

bazzbazz

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Re: seat belt pre tensioner light on
« Reply #1 on: February 07, 2019, 05:42:47 PM »
This fault was originally identified by myself to the previous owner and it was intended to be rectified at the next service, this was the plan before the owner decided to sell it.

It is usually caused by one of two problems -

1/ The insulation of the two wires going to the Explosive Squib breaking down and losing integrity, resulting in it being interpreted as a short/low resistance.

2/ Or the actual Squib igniter degrading and going high resistance.

The PROPER and CORRECT way to resolve it is to replace the Seat Belt Tensioner assembly with a newer item from as late a model 156 as you can find at the wreckers. You will hear/read of people suggesting that you can fool the Air Bag ECU into ignoring the fault using a resistor, and yes it will do that, but the fault will be there and there is no guarantee that the Tensioner will operate correctly in an impact.


The use of Air Bag Resistors are only ever supposed to be used for testing and fault finding, NEVER for "Spoofing" the ECU.
« Last Edit: February 07, 2019, 05:45:51 PM by bazzbazz »
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cc

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Re: seat belt pre tensioner light on
« Reply #2 on: February 07, 2019, 07:00:57 PM »
thanks Bazz.
Ive a pair to bring up from the parts car in Sydney. Probably in the 1st week of March.
The Alfa dealer in Brisbane has only the drivers side unit. Ex Melbourne as a new part for about $1,200.
Have emailed the Alfaworkshop in the UK asking on the availability and price of new seat belt pre tensioners over there.

bazzbazz

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Re: seat belt pre tensioner light on
« Reply #3 on: February 07, 2019, 08:34:53 PM »
You can't ship them from overseas via the normal methods - THEY CONTAIN EXPLOSIVES! They have to be shipped as dangerous goods!

Also you need to remove the pillar cover to expose the Tensioner unit, then disconnect it and make sure that you have the right one as the faulty unit. Sometimes Diagnostics will indicate it's a drivers side Pre-Tensioner but it means the LEFT side of the car, as the system was originally designed for LHD cars.

If you disconnect the unit and check with the diagnostics and there are no more errors you have the right one. If you disconnect it and it shows up an new error, you obviously have the wrong side.

And don't forget to disconnect the battery for 30 min before trying to disconnect anything to do with the Airbag System.
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(Bilstein Sports Dampers )

Fergo86

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Re: seat belt pre tensioner light on
« Reply #4 on: March 24, 2019, 10:01:54 AM »
thanks Bazz.
Ive a pair to bring up from the parts car in Sydney. Probably in the 1st week of March.
The Alfa dealer in Brisbane has only the drivers side unit. Ex Melbourne as a new part for about $1,200.
Have emailed the Alfaworkshop in the UK asking on the availability and price of new seat belt pre tensioners over there.

Hi guys my drivers pretensioner has failed, can you send me the alfa dealerīs contact you mentioned?

Cheers