Blinking Air Bag Light

[sperold]

On my 95 SHO, I am getting 4 blinks, a pause, and 2 blinks.

I have been led to believe this is the code for "Primary Crash Sensor #2 Feed / Return Circuit Open" I think there are 2 crash sensors, one on the rad saddle and one on the cowl (I think), so I would like to know which one is #2.

Frankly, just how much can you do to diagnose this issue. Could this be a sensor that has gone bad? If it is a break in the wiring, is it usually at the connector?

Would you disconnect the battery, try something, then reconnect, and see if the blinking light turns off (or the bag goes off). Is there any correct way to work on this system (like do you remove the air bag and put a meter in there or something like that)?

I would like to fix this light, but the air bag going off is not something I want to experience. I have had the airbag out, so I know some of the rules about working on it, but I could use some help on some finer points.

 

[luigisho]

I usually unhook the battery and let the system discharge for a few minutes. Maybe turn on the headlights to draw current out. I think that is the sensor by the radiator. Usually it's a faulty sensor or the connector or wiring is corroded. No way to tell about the connector/wires until you dig in and get a look at it. I have replaced 2 faulty crash sensors in the past 10-12 yrs. Pretty easy. Look for a used sensor for sale in the classifieds or ebay. Rubydist may still have some laying around for sale

 

[rubydist]

that is the front center crash sensor that it's complaining about. generally, the sensor is bad or the connector is dirty. Start by disconnecting battery, disconnect the sensor and look at the connector to see if there is apparent corrosion. if it looks clean, then the sensor is suspect.

I have at least one of those sensors in my for-sale thread, if you end up needing it.

 

[Alex Perry]

I had a wire for that sensor damaged inside the wire loom back by the master cylinder. I cut out the corroded section and soldered in a splice and sealed it back up with heat shrink.

 

[sperold]

Thanks everyone, I have had the sensor on and off a dozen times, but always put the same sensor back on. When I replaced the rad saddle, the sensor got a lot of attention, along with everything else up there.

I am going to try a few sensors from my collection and see what happens. I think I have a 93 sensor, which I hope will be the same. The airbag system is so complicated, with so many parts, that I forget it is always the simple and obvious things that go wrong.

I leave the battery off overnight when I do anything with the airbag, and then sweat it out with every move I make. All those stories of the airbag going off (especially in the early year cars like ours) have left me cold (while sweating).

 

[sperold]

I tried another sensor and got the same code flashing, so I think I have a wiring issue. (Or two bad crash sensors).
I spotted some electrical tape on the wiring near the connector, so I think that is the place to start.

 

[sperold]

Took off the tape near the crash sensor. Got a continuity meter and touched the pins while probing the splices (which were soldered). All 3 pins had continuity.
Looking for some hunches, what are the chances I have 2 bad crash sensors, apposed to a wiring problem somewhere else?

 

[Alex Perry]

Chase it further back... Check between the crash sensor and the air bag module behind the glove box.

 

[Bill Strobel]

The air bag module itself will give you the same code.

 

[sperold]

Yea, that is the problem. Broken wires or a bad sensor gives the same code. There is a separate code for the sensor not being attached to the vehicle properly. So at least I am down to only 2 possibilities.
I bought a 30 foot chunk of 16 ga wire, so I am going to do a continuity check from the sensor pin to the "air bag monitor" harness pin behind the glove box.
I can't wait to see what insurmountable problems are awaiting me. I am having a very low percentage success rate with problems lately.

 

[sperold]

Made some progress.
Did a continuity test on the 3 wires from the Crash Sensor to Connectors on Air Bag monitoring module. Wire 625 (Yellow with green stripe) described as "Feed Monitor" failed the test. The other 2 wires are feed and and ground monitor, and the harness was good between these test points..
Is running a whole new wire my solution? It is a pretty long harness and these points are pretty well at the extreme ends, so there are lots of places for problems. I am going to take a stab at it by looking at some areas that might be more prone to damage, but I am also realistic.

 

[Alex Perry]

Find the break, don't run a whole new wire. The circuit goes through the big harness bolted to the inside of the driver side fender. See if the break is before or after that. I found my broken wire in the bundle that has a ziploc-like loom around it right under the master cylinder.

 

[sperold]

Yea, I just discovered Connector 100 (monster square connector with a bolt in the center). Next week, I am taking that thing apart and see how far my circuit has power. I have another wire (for my rear defogger) going through that same connector, that takes 40 amps to my dash switch that is broke as well.
The problem with running a new wire is I have no idea where a new wire can enter the cabin, it is pretty busy in all the areas I have looked at.

 

[luigisho]

Have you used the hole on the driver side firewall that many people use to run aftermarket amp thick gauge power wire? You could fit a lot of stuff through there.

 

[sperold]

Where should I look on the drivers side for the hole, and does it have a cap on it, or anything else running through it?

 

[luigisho]

I looked for it last post and didn't see it around. Might be an old one lost. I'll look and see if I can find it again or on tcca. I don't have my car here to check it with my eyes.

http://www.taurusclub.com/forum/117-electronics-security-audio-visual/94613-firewall-hole-12.html

https://www.flickr.com/photos/39703986@N07/sets/72157620250324586/

 

[sperold]

Success!
Finally got back to this issue.
The feed monitor wire (wire 626 Y/LG) was broken between the front rad crash sensor and the box behind the glove box. It passed through the huge connector in front of the strut tower on the drivers side (C-100), so I thought I would start there.
Got the connector apart and went pin to pin from C-100 to the crash sensor, and my continuity meter read 0. Ran a new wire from the crash sensor to the top of C-100 (across the top of the rad), spliced it in and did the test again, and I got continuity, pin to pin.

Put everything back together (had the air box and tube off, and the shroud above the radiator); pushed the drivers seat as far ahead as it would go, got in the back seat, reached around and turned the key to "on", and the airbag light was on but went off in a few seconds (used to flash even with car off, but the key in "on".
Jumped in the front seat and started the car. No air bags exploded.
Air bag light was on for a few seconds, went out and stayed out.

Extremely surprised that I solved this issue, I thought that flashing light was with me forever.

 

[Alex Perry]

Glad to hear!

 

[rubydist]

good work!

 

[Banshee]

Good read. Glad that's fixed.