Hi guys I'm having a slight problem with my Xk8 passenger airbag warning light. Start the car all normal etc. While driving along if I accelerate hard or throw the car into a bend hard that airbag warning.light comes on, no flashing just constantly on until I slow down or come out the bend. This was happening at about 50 mph but didn't seem to do it with a passenger in the seat. It when the into the shop today for a few other minor problems and while they had it they cleaned the connections underneath the passenger seat. If anything this has made it worse with the car now doing it at 30 mph ish. Any idea guys?

 

Fauconberg,
The passenger seat has a weight sensor that weighs the occupant.

For safety reasons, the airbag will not deploy if a Child under approx ~35kg is sitting there (I don't know the exact weight threshold).

It is clearly this 'Occupancy sensor' that is failing or a loose connection and explains why an adult passenger is not re-creating the problem.

Read this thread
https://www.jaguarforums.com/forum/x...-error-215482/

 

Thankyou PKWise
I have been out playing with the wiring I could get to with out removing the seat and got some improvement with it. I then got my 10 year old to sit in the front while I took the car round the block and everything working perfectly and came to the conclusion of the occupancy sensor my self. I'm planning on removing the seat next week and cleaning all the wiring. So just come in and read your reply which has confirmed where I what I was starting to conclude. I suppose if the worst comes to it I can pick up a 2nd hand sensor of eBay for £150 which should be calibrated already . I will post when I get the seat out and clean up the wiring and let you know what the verdict is with just cleaning.
I would do it sooner but I'm a Iraq vet with metal plates in my back and legs and this morning has crucified me lol.

Thank you so much for your response

regards

Mark

 

Well having cleaned all the contacts under the seat today still no better. Still OK with a passenger so it does look like the occupancy sensor. The local garage suggested putting a emulator in to fool the car into thinking there is a passenger in it. They said this should clear the problem and make the airbags deploy as normal with or without a passenger. So before I get a 2nd hand sensor I will try this as a temporary fix to see if it works. Will post when I have done it.

 

Fauconberg,

Please be careful here! An emulator that bypasses this part of the safety system could be catastrophic. Please don’t let them do it.

The design prevents airbag deployment when youngsters are in the front passenger seat. This is because an airbag can seriously injure a child under 13yrs or under ~35kg. Some countries (incl. UK) ban kids in the front seat for this reason. Jaguar, however, engineered a smart system to let kids ride up front.

The sensor in the passenger seat squab is one part of an occupancy detection and measurement system (There’s two sensors!).

Together, the sensors determine:- Front passenger exists ‘YES/NO’? Front passenger weight is adult ‘YES/NO’?

So, a frontal impact of >8mph with passenger occupancy sensors outputting ‘YES’ and ‘YES’ will deploy the passenger Airbag.

Obviously, either sensor outputting ‘NO’ prevents unnecessary deployment.

Therefore, the risk taken with emulator bypass (in the frontal crash scenario) is to any child in the front passenger seat. Your local Garage suggests, there will be no affect to a passenger, but I’m sorry to say that, they have not grasped the full complexity of this smart system. What they should say is the emulator will have ‘No affect to Adult Passenger, and risk of fatality to Child passenger’.

 

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Thank you for that having played a little this morning I'm not sure it is the occupancy sensor either. Sat in the passenger seat no light lifted my weight light on. As I said only coming on when I accelerate hard and reach 50 ish I'm wondering if I have a ultra sonic sensor down. There is no fault code on it either which is making it awkward to figure it out. I did move the seat all the way forward with my knees on the dash and right up against the glove box with no lights. That's why I am now thinking ultra sonic sensor down. The roof one has been changed as I had a spare cluster. And I do have a spare a post sensor so will try that next

 

Fauconberg,

I don’t know much about the other ‘ultrasonic’ sensor. I wonder if it works on line-of-sight? If so, then alignment between emitter and receiver will be important, and of course, the security of the terminal contacts.