1993 Mercury Grand Marquis Air Bag Code 24

[friskyfrankie]

Replaced the Air Bag Module a month ago after getting a Code 52. Was good until today when I started receiving a Code 24. Internet is chock full of info but none of it is making any sense to me. Where is the place to look to offer a fix and how is it done? Seems to be a possible short or loose connector but where is "the rub"! Thoughts????

[sly]

The safing sensor is behind the driver side kick panel... behind the bracket of wire harnesses... behind the inner sheet metal inside the large hole there that all that wire is in front of IIRC. There's a 4-pin harness that goes to that one. When I started having issues with my airbag system, that's where it started. Never did find that one on my car either and then it went to code 51 all the damn time. If I can remember to when I get home, I'll get the airbag safing circuit diagram out for you.

[friskyfrankie]

The safing sensor is behind the driver side kick panel... behind the bracket of wire harnesses... behind the inner sheet metal inside the large hole there that all that wire is in front of IIRC. There's a 4-pin harness that goes to that one. When I started having issues with my airbag system, that's where it started. Never did find that one on my car either and then it went to code 51 all the damn time. If I can remember to when I get home, I'll get the airbag safing circuit diagram out for you.

Is it the sensor itself that is bad or the wiring and/or connector to it that is the issue? Is it easy to get to? Never have been in that section of the car so that is why I'm asking. A diagram would be nice and I'll see what I have here as well. Hopefully, this new fault does no harm to the new module. That would be VERY bad!

[sly]

Typically the connector needs to be disconnected and the female ends squeezed a tiny bit with some needle nose.

[friskyfrankie]

Any idea on ease of access?

[sly]

You probably just have to unbolt the harness. It is quite a mess of wires in there. May have to unbolt a few to get at that one.

I do suggest to disconnect the battery and then hit the brakes to discharge the airbag module before messing with the system, just in case.

Wiring diagram: http://grandmarq.net/sly/1993%20MGM%20Airbag.pdf
Location (bottom left of diagram): http://grandmarq.net/sly/1993%20MGM%...g%20Sensor.pdf

[friskyfrankie]

You probably just have to unbolt the harness. It is quite a mess of wires in there. May have to unbolt a few to get at that one.

I do suggest to disconnect the battery and then hit the brakes to discharge the airbag module before messing with the system, just in case.

Wiring diagram: http://grandmarq.net/sly/1993%20MGM%20Airbag.pdf
Location (bottom left of diagram): http://grandmarq.net/sly/1993%20MGM%...g%20Sensor.pdf

Thanks for the VERY informative information - looks like "fun" to get to! I'll need to figure out which one is the sensor. I know you mentioned it has a 4 wire connector - hope there is not more than one with the same number of wires.

[sly]

After looking at the diagram, it may be a 5-wire in a 6-wire harness. Not at all sure about it, but it will be the smallest connector in that batch as the others are body harnesses and have a LOT of wires in them.

[friskyfrankie]

After looking at the diagram, it may be a 5-wire in a 6-wire harness. Not at all sure about it, but it will be the smallest connector in that batch as the others are body harnesses and have a LOT of wires in them.

Good clue! Have several doctor appointments next week and may need to be hospitalized so this may be a "back burner" project. Just hope it doesn't screw up the new module but then again I don't see the car getting used much. If I can get to it, I'll look for any damage and if none is found, I'll just unplug the connector and plug it back in. May use some dielectric grease?

[sly]

Contact cleaner maybe. Since they're inside the vehicle, dielectric grease typically isn't needed unless it's prone to leaks.

[friskyfrankie]

Would have used the contact cleaner as well but I guess I am spoiled by usually also using dielectric grease after the cleaner dries. As you indicate, though, probably overkill. Hopefully, I can get to it soon but for now, have "bigger fish to fry"! As long as it doesn't damage the module it can wait.

[friskyfrankie]

Today's Update: Got a chance, in between doctor appointments, to devote some time to this issue. Pulled the kick panel, found the sensor (light blue and the proper color and number of wires according to Sly's diagram). Disconnected it and sprayed both sides with contact cleaner spray. Connectors and pins all were intact and clean. Reinstalled and still received a Code of "24". Just for grins, pulled the connector and started the car. Now I had a code of 21 (just to prove I had the right connector). Put it all back and now getting the original code "24". I was reading there is a connector, behind the glove box, that needs to be "shorter out" to clear a code of "21" but wonder if this needs to be done to clear any code from the module? If so, I'll need to find it and try the procedure. I assume it is a different connector from the one used to program key fobs? Also, will the air bag system still work correctly with fault codes or is the system non functional until no codes remain?" Thoughts????

[friskyfrankie]

Still can't find a definitive answer as to what the problem is! Back of the sensor is very tight to get to so checking voltage in and out would not be easy. Wonder if the problem is coming from elsewhere and this is a "ghost code" like Microsoft does with many Windows codes?

[sly]

You may need to remove the sensor from the side and verify the mounting point isn't oxidized. It may be sensing high resistance to ground. The resistor in the sensor may also have drifted enough to throw things off. Doubtful, but it is possible. The module rechecks everything at each startup, so codes should disappear when the issue is resolved.

[friskyfrankie]

You may need to remove the sensor from the side and verify the mounting point isn't oxidized. It may be sensing high resistance to ground. The resistor in the sensor may also have drifted enough to throw things off. Doubtful, but it is possible. The module rechecks everything at each startup, so codes should disappear when the issue is resolved.

Hope the sensor itself is ok as I have never actually seen one for sale. No sure it is mounted to anything and may simply ground through the wiring harness (with it's own ground wire). Need to check the wiring diagram as that should tell me for sure. I'll post what I find and thanks for the thoughts!