fiesta mk4/5 airbag/srs fault woes/diagnosis

[hairymel]

i have had a 1999/2000 mk5 1.6 fiesta sitting outside my workshop for 2 years waiting for me to take it for an mot.

 

this i have finally done and sadly it has failed on several issues. the only one i am having trouble with is the srs light being on (dimly)

 

the dimness has been sorted by disassembling the dash and removing the sticky tape over the srs led  

 

however this has just made the on-ness of the warning light more apparent.

 

i have a £20 autel obd scanner which shows no codes present and a pc based f-super lead and formidable 2.02 which doesn't appear to be able to connect to the ecu on the fiesta.

 

i have done the unplugging/replugging of all the connectors i can see and also swapped out the airbag and clockspring for ones of unknown provenance.

 

any ideas of a cost effective method of reading the airbag ecu or any ideas of common faults that i can test for?

 

thanks for reading 

 

 

[twosmoke300]

Thicker tape or a 1/8 drill bit through the led ? 😀

[Kiltox]

Know anyone with a Delphi DS150? Knock offs widely available from China for £50 or so......

 

Never had it fail to read anything like that

[greengartside]

Have you tried doing a hard reset on it? As it's been stood for so long the electrics may have gone a bit do-lally?

[CortinaDave]

I said in another thread.. Bulb out. No bulb is an advisory against light on which is a fail

[hairymel]

Thicker tape or a 1/8 drill bit through the led ?

 

dont really want to fudge it if i can avoid it!

 

Know anyone with a Delphi DS150? Knock offs widely available from China for £50 or so......

 

Never had it fail to read anything like that

 

will have to be uk if i get one - the retest clock is ticking

 

Have you tried doing a hard reset on it? As it's been stood for so long the electrics may have gone a bit do-lally?

 

the battery has been off but the taped over light suggests a long term problem

[hairymel]

I said in another thread.. Bulb out. No bulb is an advisory against light on which is a fail

 

the tester has been passing disreputable cars for me for years. blanking the bulb after it has failed would probably make him less reasonable in the future

 

also nuns and kittens may be involved

[Isaac Hunt]

I'm a bit 'armchair mechunic' on Air Bag faults.

 

Fused resistors for 'fooling' the Air back circuit can be found on e-bay.  

 

I 'read up' on a theory which was to fit a resistor into each plug on the circuit.  Drivers Air Back, Pass Air Bag etc etc, seat connectors.  Then if the light is extinguished, remove resistors and reconect each circuit 'one by one' until the light doesn't extinguish.  All made logical sense and might have worked for me if I had seen it through, but I ended up with some component substitution and a re-make of connections.

[hairymel]

just ordered one of these http://www.ebay.co.uk/itm/282364482974 so am either going to fix the problem before it is delivered or not fix it and the obd scanner will arrive broken

place bets now

[Guest bangerfan101]

Wd40 the yellow plug connectors under the seat. I had same on mine.

[hairymel]

Wd40 everywhere

 

my favourite thing. it doesn't always fix the problem but it smells so nice

 

i possibly have a non tensioner equipped fiesta outside so might swap out the srs box from that. or chop all the wires and twist the ends together 

[Guest bangerfan101]

I think the connectors go to the seat belt pre tensioners. If so give them a wiggle and poke after a lubing of Wd40

[hairymel]

yep - already got ya mate    i will update on any progress tomorrow 

[hairymel]

okydoky - multimetering across the seatbelt connectors showed 1ohm-ish resistance but so did touching the probes together, so i am assuming my test leads have suddenly become 1ohm resistors:? 
 
further fiddling and mooching about in my workshop unearthed another srs(and integral crash sensor i think) module.
 
swapping it turned off the srs light - yay  
 
after refitting the dash, clockspring, wheel and airbag the light came on again
 
moving around the dangling srs box seemed to be they key and happily it didn't take long for me to twig that the module needs to be earthed through its metal case, so bolting it down =light off =  again
 
after putting everything back together i noticed the revcounter was not working    
 
sigh - airbag, wheel ,dash etc apart again.
 
the dials have pins that are a push fit into the main pcb of the dash but all seemed ok there. the needle of the revcounter was all the way round to the stop, and a gentle prod back to 0 seems to have sorted it   
 
all back together now thankfully  
 
so in conclusion - either the srs brain was faulty, or the seatbelt circuit is duff somehow and i have fitted a 'non tensioner' module.
 
either way i am calling it fixed   



 

just ordered one of these http://www.ebay.co.uk/itm/282364482974 so am either going to fix the problem before it is delivered or not fix it and the obd scanner will arrive broken

place bets now

option a comes in first place!, now whats the betting option b rears its ugly head with the £65 thing i don't need now 

[twosmoke300]

Don't go probing airbag stuff with a multimeter !

The 9v battery it uses for resistance testing can be enough to deploy an airbag

[hairymel]

deploy an airbag in your face

oops - luckily it didn't 

 

have had a seatbelt tensioner go bang while i was removing it once though - proper $hit me up

 

fair point - that you could have made before i took my life in my hands 

[Guest bangerfan101]

Top bodging

[twosmoke300]

oops - luckily it didn't

 

have had a seatbelt tensioner go bang while i was removing it once though - proper $hit me up

 

fair point - that you could have made before i took my life in my hands

Didn't think anyone was silly enough to do it 😳

[hairymel]

now that just puts me in my place doesn't it 

 

in an alternate universe someone less fortunate -

 

 

 

[hairymel]

[hairymel]

[0ldCh0d]

Ouch!!!....that last video    .  

[hairymel]

 

just ordered one of these http://www.ebay.co.uk/itm/282364482974 so am either going to fix the problem before it is delivered or not fix it and the obd scanner will arrive broken

 

place bets now

option a comes in first place!, now whats the betting option b rears its ugly head with the £65 thing i don't need now 

 

interface has arrived but the software disc is blank lol

 

new one being sent by the vendor so hopefully all will be well in the end.

 

also the fiesta , after srs repair , 2 new brake lines , a backbox wobbing and 3! new wiper blades has now got a  mot certificate for the first time in 2 years