Inertia switch

[Spark plug]

Do any of you lads know where the Inertia switch is on my IS250? Thanks

[Linas.P]

Not sure in what context you are asking, but the main one that is used for stability control is below the infotainment and some vents at the central console. 

[Spark plug]

I mean the switch that cuts power to the petrol pump in a crash so petrol is not spraying everywhere. where I live there is really bad potholes and im expecting this to trigger the inertia switch and I have no idea where it is. This happened me in my first injection car  back in the 90's and had to be towed in to work early one morning only to find this switch had triggered and only needed prest in for the car to start... I think all injection cars have this kind of switch now...

[Linas.P]

Cannot find reference of that in repair manual. My assumption would be that this would be controlled by ECU (as everything fuel related is controlled by ECU) and the main sensor that feeds ECU the is this "yaw rate and acceleration sensor":

I do not believe that potholes can be that bad to trigger this sensor, perhaps it was the case in older cars, but this would be quite sophisticated sensor which looks at multiple parameters and for it to be triggered by pothole the impact would need to be such that you probably would lose parts of your suspension before you get some sort of trigger to cut-off fuel. Certainly I have never heard of that happening to anyone.

[Spark plug]

As you say modern electronics are probly more sophisticated than the 90's cars. I looked in the handbook and can't find anything about this. I was more used to working on cars with points and plugs and carbs. Electronics is over my head.

[ColinBarber]

On 4/18/2024 at 1:34 PM, Spark plug said:

Do any of you lads know where the Inertia switch is on my IS250? Thanks

It's part of the airbag system - the airbag sensors will trigger the bag(s) to deploy and also signal to the engine ECU to turn off the fuel pump.

[steve2006]

Who remembers looking at those pictures in Haynes manuals showing the various states of the spark plugs and comparing those from your own engine which at 40,000 miles was burning a quart of oil per 1000? 😀

[Spark plug]

5 hours ago, steve2006 said:

Who remembers looking at those pictures in Haynes manuals showing the various states of the spark plugs and comparing those from your own engine which at 40,000 miles was burning a quart of oil per 1000? 😀

I do. I trained as a mechanic in the 70's

[Texas]

Back in the ‘90’s I used to deliver cars for Eurodollar rent-a-car and the new Ford Sierra/Shapphire at the time had an inertial switch that was fixed in the spare wheel well that in the event of a severe rear end collision would cut the supply to the fuel relay. This was fine until you had a puncture and used the spare ( full size alloy) wheel and then chucked in the flat tyre/wheel that you have just removed back in the wheel well and knocked the sensor into cutting the fuel supply off!!! Numerous times the AA would be called to a punter who had a crank/no start after sorting a puncture themselves to simply push the reset button in the middle of this solenoid in the wheel well to get the car on its way!

[Spark plug]

14 hours ago, Texas said:

Back in the ‘90’s I used to deliver cars for Eurodollar rent-a-car and the new Ford Sierra/Shapphire at the time had an inertial switch that was fixed in the spare wheel well that in the event of a severe rear end collision would cut the supply to the fuel relay. This was fine until you had a puncture and used the spare ( full size alloy) wheel and then chucked in the flat tyre/wheel that you have just removed back in the wheel well and knocked the sensor into cutting the fuel supply off!!! Numerous times the AA would be called to a punter who had a crank/no start after sorting a puncture themselves to simply push the reset button in the middle of this solenoid in the wheel well to get the car on its way!

 

14 hours ago, Texas said:

Back in the ‘90’s I used to deliver cars for Eurodollar rent-a-car and the new Ford Sierra/Shapphire at the time had an inertial switch that was fixed in the spare wheel well that in the event of a severe rear end collision would cut the supply to the fuel relay. This was fine until you had a puncture and used the spare ( full size alloy) wheel and then chucked in the flat tyre/wheel that you have just removed back in the wheel well and knocked the sensor into cutting the fuel supply off!!! Numerous times the AA would be called to a punter who had a crank/no start after sorting a puncture themselves to simply push the reset button in the middle of this solenoid in the wheel well to get the car on its way!

I had an early 90's 2.9 Granada that hit a bad pothole one morning going to work and had to be towed into work to find the inertia switch had triggered...

[GMB]

16 hours ago, Spark plug said:

I had an early 90's 2.9 Granada that hit a bad pothole one morning going to work and had to be towed into work to find the inertia switch had triggered.

Yes, I remember the Granada was notorious for the inertia switch in the wheel arch being triggered. Apparently naughty boys would give the switch a thump and disable the car just for a laugh when the poor driver could not start it.😏