For what it worth, here’s a story of a situation that may be affecting others.
Three or four months ago a friend with a ’98 GT told me he had an “Air Bag” light come on, and stay on.
About a month or so ago he took it to a stealership, who, along with some other minor work, charged him over $300 and told him that some unspecified electrical connections were cleaned up to alleviate the problem. Two minutes after leaving the stealership the “Air Bag” light came on again. Somewhere in the whole deal my friend wound up with a large tube of silicon grease-type sealant ($$.$$) and was basically told to unplug everything (which presumably would clean the contacts within the plugs) and apply the sealant to prevent future occurrences.
This past weekend was the first chance we had to get together to go over things. In the meantime I studied the wiring diagrams and operation of the air bag light. Notably, the system runs self-diagnostics at each startup, and if something is found amiss it keeps the light on to get one’s attention to head on in for service (or lack of same in my friend’s case). Part of the circuitry of the air bag system depends on a ground connection at each of the two front primary crash sensors, which are located about a foot either side, up behind the Mustang in the grill opening. They look like black metal boxes, about 2” x 2” x 2”. I reviewed the physical arrangement of the wiring to the crash sensors on my Cobra (same setup on a GT) and found that the ground is not a wire (as is very common in these times of plastic everything), but, as in the good olde days, is made between the sensors’ bracket and the radiator cross-member by the screws that attach the sensors to the cross-member. I surmised something was corroded or loose on my friend’s GT.
While I had been to various car shows with my friend and his GT in attendance it wasn’t possible at those times to inspect the crash sensor mountings because he had had an after-market chrome-plated cover installed over the area around the hood latch and extending back to the radiator expansion tank, and sideways to the fenders. With the cover in place nothing was visible. So that’s where I had to start: removing the chrome-plated cover. There must be a dozen stainless steel screws holding the thing down, in addition to two nuts holding the radiator expansion tank to it also.
Once the cover was off it became obvious why the air bag light had come on. Each sensor bracket is bolted to the cross-member with two screws. These screws had been removed to allow the chrome-plated cover to be put in place, and then two each stainless steel screws had been inserted from the outside through the chromed plate, through the sensors’ brackets and into the captive nuts within the radiator support cross-member. This essentially left the sensors’ brackets sandwiched between the chrome cover and the cross-member with no specific provisions to assure a proper electrical ground connection. Time simply caught up with this deficiency and flipped on the light.
It was very evident that the original bolts had done their electrical ground conducting job as the area where the bolt heads contacted the brackets was scraped clear of paint.
The fix was to install a ground wire from the brackets to the ground connection (the green screw(s)) at the ends of the radiator support cross-member.
I guess when the stealership saw all of that fancy mirror-finish chrome plated stuff under the hood of this car they were “blinded by the light” and lost all sense of just where those crash sensors were, and just how the air bag system functions! Kind of makes you wonder if they have any idea of how our cars work?
So, if you’ve played around with the mounting hardware of your crash sensors and achieved an illuminated “Air Bag” light in the process, make sure that you get a proper ground circuit re-established because the air bags may not function with that light on.
Three or four months ago a friend with a ’98 GT told me he had an “Air Bag” light come on, and stay on.
About a month or so ago he took it to a stealership, who, along with some other minor work, charged him over $300 and told him that some unspecified electrical connections were cleaned up to alleviate the problem. Two minutes after leaving the stealership the “Air Bag” light came on again. Somewhere in the whole deal my friend wound up with a large tube of silicon grease-type sealant ($$.$$) and was basically told to unplug everything (which presumably would clean the contacts within the plugs) and apply the sealant to prevent future occurrences.
This past weekend was the first chance we had to get together to go over things. In the meantime I studied the wiring diagrams and operation of the air bag light. Notably, the system runs self-diagnostics at each startup, and if something is found amiss it keeps the light on to get one’s attention to head on in for service (or lack of same in my friend’s case). Part of the circuitry of the air bag system depends on a ground connection at each of the two front primary crash sensors, which are located about a foot either side, up behind the Mustang in the grill opening. They look like black metal boxes, about 2” x 2” x 2”. I reviewed the physical arrangement of the wiring to the crash sensors on my Cobra (same setup on a GT) and found that the ground is not a wire (as is very common in these times of plastic everything), but, as in the good olde days, is made between the sensors’ bracket and the radiator cross-member by the screws that attach the sensors to the cross-member. I surmised something was corroded or loose on my friend’s GT.
While I had been to various car shows with my friend and his GT in attendance it wasn’t possible at those times to inspect the crash sensor mountings because he had had an after-market chrome-plated cover installed over the area around the hood latch and extending back to the radiator expansion tank, and sideways to the fenders. With the cover in place nothing was visible. So that’s where I had to start: removing the chrome-plated cover. There must be a dozen stainless steel screws holding the thing down, in addition to two nuts holding the radiator expansion tank to it also.
Once the cover was off it became obvious why the air bag light had come on. Each sensor bracket is bolted to the cross-member with two screws. These screws had been removed to allow the chrome-plated cover to be put in place, and then two each stainless steel screws had been inserted from the outside through the chromed plate, through the sensors’ brackets and into the captive nuts within the radiator support cross-member. This essentially left the sensors’ brackets sandwiched between the chrome cover and the cross-member with no specific provisions to assure a proper electrical ground connection. Time simply caught up with this deficiency and flipped on the light.
It was very evident that the original bolts had done their electrical ground conducting job as the area where the bolt heads contacted the brackets was scraped clear of paint.
The fix was to install a ground wire from the brackets to the ground connection (the green screw(s)) at the ends of the radiator support cross-member.
I guess when the stealership saw all of that fancy mirror-finish chrome plated stuff under the hood of this car they were “blinded by the light” and lost all sense of just where those crash sensors were, and just how the air bag system functions! Kind of makes you wonder if they have any idea of how our cars work?
So, if you’ve played around with the mounting hardware of your crash sensors and achieved an illuminated “Air Bag” light in the process, make sure that you get a proper ground circuit re-established because the air bags may not function with that light on.
