SRS air bag lights...

SRS air bag lights...

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dave_s13

Original Poster:

13,814 posts

270 months

Saturday 17th November 2018
quotequote all
Car is a Kia Magentis 2.0 petrol, obviously you are all very envious. It's on an 06 plate, 46k miles, loads of MOT and cheap

Anyway, airbag light is on. I managed to find some broken wires on the drivers side seat belt buckle so took it apart, soldered the wire up and ....the light is still on. Checked passenger side wiring and that all looks good, there's some sort of control module under the passwnfer seat too, maybe the occupancy sensor? But all wiring looks sound.

The question is, do air bag codes remain even when the issue is fixed until you reset then with a scan tool? I've hopefully got someone coming to have a look at it next week who has the proper diagnostic kit. I'm hoping that if he can't just reset the system he can at least identify the faulty component.

The other option might be to buy a diagnostic kit that will talk to the airbag system, anyone any thoughts on the above?

Thanks in advance.

dave_s13

Original Poster:

13,814 posts

270 months

Saturday 17th November 2018
quotequote all
DuraAce said:
Depends on the car. Some will self test and then turn the light off, some will need it doing with a scan tool even if the fault is fixed.
5 minutes with diagnostic kit will tell you.
I use an Autel scanner and it does the job ok.
Cheers for that.

Guy is charging £50 to come and plug it in.

Can get this for £80..

http://m.obd2shop.co.uk/wholesale/launch-creader-6...

Even cheaper on the bay.

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2...

Might be a handy thing to have, especially if it can talk to my other car, a Jap import... probably won't though.


Edited by dave_s13 on Saturday 17th November 21:04

dave_s13

Original Poster:

13,814 posts

270 months

Saturday 17th November 2018
quotequote all
Cheers. I'm hoping it's that simple. Seems too low mileage for a clock spring to go.

Probably best to get the Pro auto electrician to look at it. At least then if resetting the light doesn't work he should be able to isolate the problem.

dave_s13

Original Poster:

13,814 posts

270 months

Saturday 17th November 2018
quotequote all
I'd definitely buy one if it'd also speak to my other car. Is a jap import nissan Elgrand though and uses the nissan specific consult 2 protocol so is a bit niche. I'm pretty sure the one I've linked to won't do it.

Does your kit speak Japanese?

I do like tinkering with cars, bought this one with a buggered door lock and the airbag light for cheap. Fixed the door lock via YouTube and a Dremel multi. If I can get the light sorted for 50 quid it's still a bloody cheap car.

dave_s13

Original Poster:

13,814 posts

270 months

Sunday 18th November 2018
quotequote all


Got the codes read and it cleared off the seat belt buckle fault but left we with the above. So at least I know what the problem is.

Just having a look into options re bypassing the seat mat sensor. This car will never have and young kids in the front and it's no like the seat sensor is an easily available part, with a quick Google anyway. Dread to think what Kia would charge for one.

dave_s13

Original Poster:

13,814 posts

270 months

Sunday 18th November 2018
quotequote all
E-bmw said:
The thing is, it is not just kids.

If anyone is sat in the front passenger seat & the sensor is defective you have to ask the question.

In an accident necessitating air bag deployment will the passenger airbag go off with that fault?
As per what Gonzales said the emulators default to an occupied with an adult position so the airbag will go off in an accident.

As long as no babies or small kids sit there it's no problem.

This is a £600 car and it's getting fixed in the cheapest possible way I'm afraid.

I also had a Clio with the ubiquitous airbag light. Give the wiring under the the seat a wiggle and it would go out for weeks at a time.

dave_s13

Original Poster:

13,814 posts

270 months

Sunday 18th November 2018
quotequote all
S. Gonzales Esq. said:
I don’t know about Kias, but when I made up an occupancy sensor bypass for my ‘97 BMW it was possible to make the system think the seat is permanently occupied. Never going to use a rear-facing child seat, so that seemed like the best option. It worked out at just £2 in parts btw.
I can't help but think sticking a resistor in the terminal would trick it. And cost 20p. I assume it's currently open circuit. The connector from the control module under the seat to the car has 3 wires, can anyone here make a guess as to what they do??

dave_s13

Original Poster:

13,814 posts

270 months

Sunday 18th November 2018
quotequote all
Actually, thinking about how it's wired.

This is under the passenger seat



The white terminal is the cable from the seat cushions sensor. The green terminal goes on into the car.

I'm assuming that white terminal feeds in a signal that varies it's resistance depending on the weight of whatever is on the seat. I'm not electronics wizard but I wonder if chopping that wire and sticking a potentiometer in there might feed a signal into that control box it's sees as normal, I assume at the moment it's open/closed circuit. What I probably need to know thougb is what resistance = adult in seat so fire the airbag.

Don't suppose anyone on here has access to wiring diagrams for these do they?

Edited by dave_s13 on Sunday 18th November 18:17

dave_s13

Original Poster:

13,814 posts

270 months

Sunday 18th November 2018
quotequote all
Cheers.

After much googling I've found the part I need.

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2...




About £100 for a new seat pad sensor. Not an inconsiderate sum on a shed. Saying that, it's only on 46k miles and the interior looks and smells new!

Just waiting to hear back from some eBay sellers that do the emulators. They are probably just a few pennies worth of electronic components in a sealed box.

Don't suppose you have a link to the BMW guide do you? I suspect they work in pretty much the same way.

Edited by dave_s13 on Sunday 18th November 21:21

dave_s13

Original Poster:

13,814 posts

270 months

Sunday 18th November 2018
quotequote all
Nice one.

It's not gonna cost much to knock this up, plug it into the seat sensor input at the control module under the seat and see what happens.



Only trouble is I've got to pay someone £15 a pop to get the codes cleared.

dave_s13

Original Poster:

13,814 posts

270 months

Tuesday 20th November 2018
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drdino said:
dave_s13 said:
Only trouble is I've got to pay someone £15 a pop to get the codes cleared.
Did you try to clear them by disconnecting the battery and leaving it like that for 10-15 mins?
Good point. I did do that but as there is an actual fault with the seat occupancy sensor it didn't go out.

Bought a resistor, diode and capacitor off ebay for about £5 delivered.

When that arrives I'll disconnect the battery, make up the emulator and see if that clears it.

dave_s13

Original Poster:

13,814 posts

270 months

Friday 23rd November 2018
quotequote all
So yesterday the airbag light went off randomly and worked both times I drove the car that day. Now it's back on again.....grrr.

This makes me think it actually doesn't need resetting with a scan tool once everything is working.

So I tested the seat sensor with a multimeter and it seems to be working in that the resistance changes with or without someone on the seat. Tried the emulator trick and no joy.

That leaves this box of tricks as the being the likely culprit



Not on eBay though, need to check some breakers and what not.

dave_s13

Original Poster:

13,814 posts

270 months

Friday 23rd November 2018
quotequote all
Penelope Stopit said:
Now that you know that a reset isn't needed.....With the car running and the light out you could work your way along the loom with a wiggle and a waggle to see if there is a break or bad connection somewhere.....the light will come on if there is a open circuit somewhere
I've kinda done that but could have a closer look.


Only place I can find that box of tricks is off a random polish website.

I'm half tempted to just run it til the mot expires in June, wack it on Ebay as is and just buy a new shed. The bloody thing has only got 46k miles on it and it's like new inside but it's worthless with this bloody light on.

dave_s13

Original Poster:

13,814 posts

270 months

Thursday 6th December 2018
quotequote all
I finally found, purchased and received a used PPD unit as per previous picture. Plugged it in and....zilch. Light still on!!

Fortunately I can send it back with it only costing me the postage.

Checked the wiring to thay box, earth is good but it's getting zero power. Why the fark didn't I check that 1st!! This points toward a possible fault with the wiring to the SRS control module or the module itself. So next job is to find that and try and trace the wire back to check for power at the required pin. It's then either a broken wire, or a fked SRS module. Can't help thinking it'd be worth bodging a live feed from somewhere else into that box to see if that doesn't he trick.

Grumble....this is turning into a right pain in the arse for what is essentially a bit of a pig of a car.

To add to my woes the EML came on a couple of days ago but I cleared that off with my basic obd tool. It's had a bit of a lumpy idle since I bought it a couple of months ago. Looks like the short term fuel trims are a bit off and the downstream O2 sensor output looks dodgy. Managed to get a used sensor anyway see if that sorts it. If I can't get this airbag light off though it's going on eBay for someone else to mess about with, while it's still got 6months+ MOT.

Edited by dave_s13 on Thursday 6th December 19:35


Edited by dave_s13 on Thursday 6th December 19:37

dave_s13

Original Poster:

13,814 posts

270 months

Monday 17th December 2018
quotequote all
So. Thought I'd bring this to a thrilling conclusion!!

Bear in mind through all this I'd convinced myself the actually passenger seat occupancy sensor must be ok, given the low miles on the car, as new condition of the seat and the fact its resistive output changed with sat in Vs not sat in states.

After trying a DIY emulator (see prev links in the thread) and an occupancy sensor module without joy I tried an airbag control unit from a breaker. Still no joy.

So bit the bullet and paid a nice chap to come round and plug it into a proper bit of kit. At this stage I'd put the original airbag ecu back in. This confirmed the ECU was in fact faulty as was the occupancy sensor itself (not the module is tried to replace). So £50 lighter I put the new ECU in place and he checked the codes again, only thing left was the seat sensor. Getting there now.

So, armed with this new info I decided to try some buggering about with the bits I had, with a bit of trial and error I managed to knock up an emulator that actually works! Turns out the seat sensor module needs to see somewhere in the region of 15ohms and it sends the ok signal. Result.

This means you need 3x 56k resistors in parralell, not just the on as per the previous links.

A bit long winded but anyway, if you now Google this issue it might lead back here and help someone else. You can't actually buy emulators for these cars btw....you can for everything else ever made.

And yes I know it will now kill small children sat in the front but it's a risk worth taking in this case.

Tldr: car had 3 faults when I bought it

1. The main airbag ecu was faulty.
2. The occupancy sensor was faulty.
3. Driver's seatbelt buckle wiring damaged.

Airbag ecu was £19 delivered off the bay + £75 in total for the code reading.

Car has a reprieve now and I'm quite pleased with it now. It runs and drives pretty sweet really.









Edited by dave_s13 on Monday 17th December 15:26

dave_s13

Original Poster:

13,814 posts

270 months

Tuesday 18th December 2018
quotequote all
GreenV8S said:
Now you've got it working, will you replace that screw terminal connector with crimped or soldered joints?
I should really shouldn't I.

It's all taped up securely and not flapping about in the wind or anything (which would probably lead to the wires failing in the screw terminal). I'm tempted to leave it for now but will probably go back and do it properly at some point, it's not making my teeth itch or anything :-)