Attleborough, Norfolk
You may have noticed I'm dabbling a lot with these failing airbag modules on the pre-facelift E85s lately? A lot (though not all) have failed due to water ingress and I have been recommending that anyone with one of these and a couple of hours spare may want to seal them in poly bags as a bit of future proofing.
Well it seems there is an important caveat with that.
I gave [ref]Usel[/ref] a couple of failed SBSLs to see if he could find anything wrong with them. in the course of his investigation he discovered that three of the six screws holding the back plate on the module are designed to earth the PCB to the casing and thence back to the car through the mounting studs.
I mentioned this to [ref]bigwinn[/ref]. He had a car in and had bagged up the modules as a precaution, but soon after it came up with a module failure. Once we'd discussed the earthing route, he took the bags off and lo and behold, the fault went away. He'd done too good a job with the bagging and prevented the module from earthing.
When I do them I have a habit of ensuring the poly bag is holed where it pushes over the mounting studs. I do this as I don't like the idea of the plastic jamming up the threads. So it appears I was avoiding the earthing issue without realising I was doing it.
As I have been quite vocal in suggesting the bagging up of these modules I wanted to make sure I wasn't causing anyone to enduce faults.
So it's up to you: if you bag them then be sure there is a good metal to metal contact between the mounting stud, securing nut and body of the module.
Well it seems there is an important caveat with that.
I gave [ref]Usel[/ref] a couple of failed SBSLs to see if he could find anything wrong with them. in the course of his investigation he discovered that three of the six screws holding the back plate on the module are designed to earth the PCB to the casing and thence back to the car through the mounting studs.
I mentioned this to [ref]bigwinn[/ref]. He had a car in and had bagged up the modules as a precaution, but soon after it came up with a module failure. Once we'd discussed the earthing route, he took the bags off and lo and behold, the fault went away. He'd done too good a job with the bagging and prevented the module from earthing.
When I do them I have a habit of ensuring the poly bag is holed where it pushes over the mounting studs. I do this as I don't like the idea of the plastic jamming up the threads. So it appears I was avoiding the earthing issue without realising I was doing it.
As I have been quite vocal in suggesting the bagging up of these modules I wanted to make sure I wasn't causing anyone to enduce faults.
So it's up to you: if you bag them then be sure there is a good metal to metal contact between the mounting stud, securing nut and body of the module.
