Hi,
Wondered if anybody could offer any further advice regarding a Passenger Airbag warning lamp that I can't seem to get to the bottom of, Or fix. I was on a Scotland drive last year (my son was in the passenger seat) and not long after we left an Airbag light came on. No matter what I try, I cannot get the light to stay off... my MOT has now expired and I'm running out of ideas 😞
Checking it out with
iCarsoft
, fault code is:
'801c - Passenger thorax airbag, short circuit to ground'
I did some research on forums and FB Groups and tried the most popular fix:
Raise the passenger seat up and down and push it forward and back a few times and make sure it's not resting on the bulkhead......
This didn't work.
Today I've removed the complete passenger seat, unclipped the harness under the seat. Checked for any bent connectors, corrosion on the terminals, I've sprayed electrical contact cleaner into both connectors. I've also checked the harness under the seat as much as I can to make sure nothing is trapped and sprayed cleaner into a couple of other smaller connectors under the seat. Couldn't see any obvious signs of damage to any harness....
initially the code cleared, but 2mins later... BACK ON AGAIN.
I'm kind of running out of options tbh and looking for some advice. Only ideas I have are:
1: Find another passenger seat and see if I can get the code to clear (thus narrowing it down to the seat)
2: Try and replace the harness going to the seat thorax airbag (somebody on youtube has done this, but it looks quite complicated).... I've got the expensive sports seats so do not want to damage them.
3: Pin it out, or find some sort of Module to bypass the seat airbag - Not that keen on this because obviously the airbag will not operate and I'm often driving with my son in the passenger seat.
Has anybody else been in a similar position or could offer any advice please?
In I wild coincidence I came across this post while looking for something about the wiring harness. I found this video that seems to discuss the exact issue you're having:
This guy had to replace the wiring harness in the seat!
For the short term to pass MOT, maybe you could code out the passenger-side thorax airbags? You can do this with the Foxwell NT530, not sure about iCarSoft. The option is in the POSIP menu.
You can also undo the front seat bolts and lift the seat up to check if the wiring harness is frayed or pinched. They are E12 torx I believe. Torque to 50 Nm when putting them back.
Thank you for all the advice.
Since last weekend.. I’ve borrowed PoCom and hooked it up to my car to read the exact resistance showing on the ECU….. Drivers airbag thorax showing a steady 2.6Ohms - Passenger thorax is a constant 0.00 Ohms… therefore there is absolutely no current getting to the airbag which definitely points at a break in the harness somewhere.
Since taking the seat out and fiddling with the harness under the seat.., the fault now shows up 100% of the time (which it didn’t before).
Next
steps (I think)
1. Take passenger seat back out.
2. Purhase a 2.6Ohm resistor dongle thing off eBay - test the ‘car side’ of the connector by putting the resistor into the car side plug and checking I get a 2.6Ohm reading on PoCom and fault clear. This would be rule out Car Side harness faults (in theory).
3. Use a multimeter across the x2 terminals on the seat harness (+ve and -ve) on continuity / bleep mode… and check / confirm if the harness break is in the seat.
4. If pin point harness break to the seat… I’ll order a new harness and get a seat trimmer to fit it for me from work.
Thats my plan anyway !
I'll use your eBay resistor procedure to debug a harness fix I just did on the car side!
I also wonder if the weight sensor affects the airbag resistance. I had a similar issue on my Audi S3 and it went away after I sat in the passenger seat and started the car.
Had another go at this over the weekend and I’m running out of ideas tbh.
1. Done a continuity test on the seat harness - Positive
2. Continuity test of the harness which runs from seat connector to the ECU under the seat - Positive
3. Tried using a 2.6Ohm resistor in the correct terminals of the car side connector and that still wouldn’t make the airbag warning light go out… nor could I get a resistance reading on POComm.
4. Had another look at the terminals on the seat harness and made sure they were straight and tweaked them slightly …. Plugged the seat back into the car and hey presto… I managed to get a resistance reading of 2.6-2.7Ohms on POComm … which I thought meant I’d solved it!
5. Even though I can now get a resistance reading (whereas before it was Zero)…. I’ve still got the same constant fault code and airbag warning lamp… no matter what I do.
Running out of ideas now tbh… why would I be getting the correct resistance reading on passenger side now and still constant fault code pinging up even when cleared. Starting to wonder if it’s the ECU.
Any ideas welcomed.
I'm going to post this - and please DON'T be insulted - I don't think you missed it - but just in case, you are clearing the codes after each change correct? Just cycling the ignition will not turn the light off once a SRS fault is logged, it has to be cleared.
Yes absolutely… clearing the codes properly .. I’ve cleared them with both PoComm and
iCarSoft
… and they only clear briefly and come back on.
