Airbag Light

[1991MGM500]

Hello, i have my 91 Grand Marquis flashin its airbag light thrice. Any clues as to what to look at? I was reading in a different topic on here that…

“3=Air Bag Deployment Circuit - Low Battery Voltage or Low Backup Power Supply Voltage”.

I was thinking maybe my battery or alternator could be the cause too, but not sure.

[friskyfrankie]

Its OBD 1 but there should be a code for it. I forgot the exact explanation but if I remember correctly something like a Code 52 is the Air Bag Capacitor module behind the glove box. The capacitors go bad and won't hold a charge so you get a code. Had that on my Dad's '93 GM and that was what it was - a LONG time ago so not even certain that is your issue. If it is, that module was around $200 back then but maybe one can be found for cheaper. Would be nice to get a new one (if that is your issue) as you have no way of knowing how good the caps are on a used module. .

[1991MGM500]

Its OBD 1 but there should be a code for it. I forgot the exact explanation but if I remember correctly something like a Code 52 is the Air Bag Capacitor module behind the glove box. The capacitors go bad and won't hold a charge so you get a code. Had that on my Dad's '93 GM and that was what it was - a LONG time ago so not even certain that is your issue. If it is, that module was around $200 back then but maybe one can be found for cheaper. Would be nice to get a new one (if that is your issue) as you have no way of knowing how good the caps are on a used module. .

I’ll have to give that a look either way, but I thought pre 92 used single digit codes. Wonder if your example would be similar to mine.

[sly]

he should have single digit codes. 2 digit codes didn't start until somewhere in 92-93

http://www.grandmarq.net/vb/forum/technical/aero-whale-tech/electrical-and-wiring-hvac/33903-air-bag-light?p=808454#post808454

As for where to look for the backup battery, that should be in the air bag module itself. This means that the capacitors that function as the backup battery in the module are shot or the wire harness is maing a bad connection somewhere between the module and the main battery IIRC.

[gadget73]

I think its actually external to the module, but in a box right next to it. Its two big capacitors in a plastic case. I think its got a 2 wire connector to it. Same system on my 91 Mark VII, but it may be physically located in a different spot on the panther cars. On a Mark VII it lives up above the glovebox though.

[friskyfrankie]

Right - two digit codes were from 92 or 93 (as I said my Dad's GM was a '93) so I am used to that. At least in a '93 GM, the caps are in that blue module behind the glove box. Not sure of the setup in a '91.

[sly]

Yeah, in panthers it should be behind the glove box on the air plenum if it's the same as the 93s. I suspect as much since the dash is very similar to the early aeros.