I had tried searching existing threads for "air bag", but found nothing. Had not used the form much, so not sure I'm using the search correctly.

My vehicle is a '98 Ram 2500 with diesel. My instrument cluster air bag light had been staying on. Scanning gave code 37, "squib short circuit". After erasing the code, it would re-appear on the next scan. For anyone with no experience with this, the squib is a small explosive charge activated by an electrical element. When the accelerometer in the air bag control module senses the sudden jolt of a collision, the controller sends an electrical current to the squib. This ignites a small explosive charge that blows the plug from a high pressure argon gas cylinder that inflates the air bag. To do the scan, you need a well featured scan tool that includes SRS functions. That means "supplemental restraint system". The cheaper scanners do not have this function.

I removed the air bag and probed the squib connector pins with an ohm meter. Sure enough the meter read close to zero ohms. Another Dodge repair web site had a post saying that the resistance should be 2.9 ohms. I removed some air bags at a u-pull junk yard, and they all measured zero ohms. Was wondering if all air bags deteriorate into this condition. My Haynes manual gives no detailed info on air bag troubleshooting. My Chrysler shop manual has quite a lengthy air bag section. It only tells about testing with a scan tool, and how to replace the air bag. It has no mention of a load resistance test. It lacks some fundamental info. It does not even tell that the resistance should be 2.9 ohms.

Had to visit a Dodge dealership and quizzed a Mechanic. They normally plug a load resistor into the vehicle harness to simulate the squib resistance. The load resistor is a special dealer tool. But they can be found on EBay. If the scan code does not re-appear with test load connected, they know that either the air bag or clock spring is bad. The Mechanic offered to do the testing, but at a price of $68 for a minimum 1/2 hour labor charge. The clock spring is a whole other component on the steering column that provides a flexible connection to the air bag and other steering wheel mounted electrics, usually the cruise control switches, and horn switch. The Mechanic also mentioned a shorting bar in the air bag connector. I had noticed a thin metal clip inside the connector socket, but supposed it to be a spring clip to retain the harness connector. Two small contacts on this tiny ring shaped part actually flex and contact the two air bag connector pins while the harness plug is removed. This is intended to prevent static electricity from setting off the air bag. When the harness is plugged in, the connector forces the contacts off the pins, removing the short circuit.

I was able to use a plastic tie wrap to push a shorting bar contact off a pin. Low and behold, I measured 2.1 ohms !. The air bag itself was ok. The shorting bar had obviously bent and made permanent contact, and the harness plug was unable to force the contacts off the pins, hence the permanent short circuit. I had obtained some low value quarter watt resistors from an electronics shop. I pushed the terminals of a 2.7 ohm resistor into the harness connector pins, and scanned for codes. Disappointingly, I still got the short circuit squib code again. Close examination of the clock spring harness that plugs into the harness connector under the dash showed another shorting clip inside the clock spring connector. I was able to pull it out with needle nose pliers. I connected everything back together, and did another scan. Victory ! Air bag light stayed off after erasing the code and doing a second scan !

The Dodge dealer Mechanic told me not to remove the shorting bar. Guess that he was afraid of static causing my air bag to blow up in my face. It was quite humid weather, so I took the chance. Other online forms warned against probing the air bag with a meter. Guess that they are afraid of the ohm meter current setting off the air bag. Ohm meter currents are quite low, so I was not concerned. Well, mine did not blow up in my face, but I must caution readers on the possibility of such danger. You must decide for yourself what degree of danger you are willing to chance.

The shorting bar in the air bag connector socket is a tiny, precision bent ring shaped thin metal stamping. I damaged mine by removing it from the plastic bushing it sits in. Really, there is no need to remove it. If you decide to take the chance of probing your air bag with an ohm meter, you really just need to unseat one of the shorting bar contacts by slipping in a plastic shim between connector pin and shorting bar contact. A 2 inch length cut off a 1/8 inch wide tie wrap does the job nicely. Be sure to use a sharp blade to cut a chisel point on the end, and be sure to orient it so that the angled side of the point is toward the shorting bar contact. This should prevent permanently bending the contact.

As for the shorting clip inside the clock spring harness connector, I have not found out how the truck harness connector unseats it. May opt to leave it out. It is only needed for safety when removing the clock spring. A piece of about 16 gauge wire can be inserted into both connector pins for a safety upon unplugging connectors for servicing the air bag system. Of course the shorting clip is not supposed to make contact with everything connected as normal.

So what had caused this problem ? Can't be completely sure. But the clock spring harness connector that plugs into the air bag is a very loose fit. There is a retaining clip for it on the air bag, but it does a terrible job of holding the plug. Suspect that vibration had caused the plug to bend the shorting bar contacts, so that they stayed connected, even with the plug seated. While maneuvering the air bag back int its place, the flimsy plug unseats. My remedy was a few dabs of hot melt glue to keep it in its place. Silicon sealant or caulking might work, but you would need to wait for it to cure.

Is the air bag needed ? Well, an air bag can kill a person, and lack of an air bag can kill a person. States and provinces that have annual safety inspections require that air bag warning lights be off, or the inspection Mechanic will not pass the vehicle. If you are in a jurisdiction that does not have safety inspections, then it is your choice on whether to drive with a non functioning air bag. One more note on safety, shop manuals warn to disconnect battery ground and wait two minutes before doing any work on air bag system to prevent accidental deployment, which could be could cause serious injury. One more tip, when looking in manuals, you may not find any indexed reference to "air bag". It may be listed as "passive restraint system," "supplemental restraint system", or "SRS". Code scanners will call it "SRS".

Hope that this info helps someone to shorten an air bag wild goose chase.

 

Nice write-up. Thanks for sharing this information. If you have any troubleshooting photos to add to it as you went through the process (since the service manual tends to be lacking in this area), that would make it even better.

 

Thought I ought to put it out for users to see, since the info in the manuals is so lacking in critical details. It is the product of hours of testing, a trip to a Dodge dealer to quiz a Mechanic, and three trips to U-Pull junk yards. I had not mentioned that initially, I had fitted a new clock spring. I like seeing old Ram II's around, so glad to share my school of hard knocks lessons to help keep these old beasts running.

I had forgotten to mention something that is not obvious. The shorting bar inside the air bag connector is tiny, and inside a very small hole. The contacts of the shorting bar are difficult to see, almost need a magnifying glass. So a lot of my trouble was because of the shorting bar contacts not being visible on a casual look. I would like to emphasize that the clip intended to secure the clock spring harness connector to the air bag does a very poor job. I consider it essential to secure the connector with hot glue, or perhaps silicone sealant. Of course with silicone, you will need to wait a while for it to cure before fitting the air bag back in place. If not glued in place, it is likely to disconnect, and your air bag will not work if needed, or at least your air bag light will stay on when the plug pops out. To do air bag trouble shooting, you need to spend whatever it takes for an SRS capable scan tool, if you do not already have.

I was just at the U-Pull junk yard and found that the truck harness connector that connects to clock spring harness connector has small spurs that force the shorting bar in the clock spring connector away from the connector pins. My original spurs broke off while removing the pins to connect the 2.7 ohm test resistor. They are very fragile. I would not recommend dismantling the connector. Best to find some single strand wire or thin sheet metal to insert, and connect the test resister to them. I'll be chopping off my old connector and fitting the one that I got at the junk yard. U-Pull junk yards are so handy for getting little parts that conventional junk yards do not handle.

I got a U- Pull junk yard air bag for $40 Canadian. I saw used air bags on EBay for about $80. Chrysler discontinued them a few years ago. The Dodge dealer parts counter guy told me that they were the same on 1997 to 2000 Dakotas. I did pull a few off Dakotas. But they looked different. A metal stamping that forms part of the housing is round on the Dakota air bags, but it is rectangular on the ones in my '98 Ram. The harness socket is in the middle of the Dakota air bags. But on the Ram one's it is on a side. This may not matter, would need to do a trial fit to see if the Dakota units will really fit a RAM. Dealer also said that 98 and 99 Durango air bags are the same. Did not find a Durango at the junk yard to examine. The air bag is quite easy to change, only need an 8 mm or 5/16 quarter drive socket and ratchet. There are two bolts at back of the steering wheel spokes, but bolts are set deep onside holes. A deep socket works well, or regular socket with short extension. Harness connector to air bag and horn switch wire are the only connectors, and come apart easily. If you can only find a Dakota or Durango air bag, see if the junk yard will refund you before you buy it, in case it will not fit your Ram. You can easily do a test fit in the junk yard parking lot. Another handy spare to get is the air bag control module. It is located atop the transmission hump just below the dash board. Need to remove four small bolts with 10 mm socket. The connector has a red tab to slide back to free the connector. I found a module at a U-Pull for just under $40 Canadian. Beware that the shop manual says that if the control module gets dropped, it is no longer good. Handle with care. Guessing that the internal accelerometer is easily damaged. Ram III's have the sensors somewhere behind the head lights, according to some other forum.

If you suspect that your clock spring is bad, and want to remove it, you will need to remove the steering wheel. Will need, a 21 mm socket with 3 inch extension, and steering wheel puller. Note that the steering wheel must be centered before removing the clock spring, and the clock spring must not be turned while off the vehicle. Failure to insure this will cause the clock spring to be destroyed after installing and turning the steering wheel. If your clock spring does go off center, the shop manual has a procedure for centering. Basically, with clock spring removed from vehicle, turn the hub in one direction until it will no longer turn. Turn it in the opposite direction and count the turns until it will no longer turn. Then turn it back in opposite direction half the number of total turns. This will be the center position. The inner spool has locks to disengage for turning, and they can be locked to maintain center. When you fit it back on the steering column, make sure that the steering wheel is centered. The hub lock will disengage by itself. The steering wheel nut should be torqued upon fitting back. The Chrysler shop manual lists the torque as 45 foot pounds.

In addition to the air bag system, the Quad Cab models have a special control system for the seat belts. This is because conventional inertial activated seat belts cannot be used due to there being no door post for securing them too. My next trip to the U-Pull could include some spare seat belts and control module. The module is under the middle of the seat, somewhere above the the transmission hump. According the the manual, the seat has to be lifted to get at the module, as it is secured to the seat underside.

In the mean time, I have to replace the ignition switch. Have a new "Standard" brand switch on order. Beware that the ignition switch screws are anti temper torx, another nuisance. The center posts will bend enough by hitting a medium size slot screw driver against them with a hammer. I bent them over in one direction, then back in opposite direction. Gotta do this carefully, or you may not be able to remove the screw if post does not bend just right. I hammered my torx bit into the screw head to seat it for turning. Best to get a set of torx anti tamper screw drivers or bits before starting the job. I will be fitting mine back with normal slot or Philips head screws. The steering column shroud screws are torx, but I was able to turn them with a no. 1 Robertson. Two of the three screws are set deep inside holes, so not accessible with changeable bits.

Part Numbers:
Air Bag
From Dodge Dealer Parts Counter: 5HH12DX9AA, was discontinued Feb 21, 2014
Lists for 97 - 2001 Ram, Regular & Quad Cab, Dakota 1997 - 2000, Durango 1998-1999

Bar Code Sticker on back of air bag: P5GD49JX8AA, Stamped number on back of air bag: 1PG998501. Note that the numbers on the part can be different, but it can still be the same part.
Rock Auto: 55350885AA, 56043355AB. Rock Auto says not in stock.

Air Bag Control Module:
Sticker on unit in 1998 Ram: P56043128AB
From Dodge Dealer Parts Counter: P56043128AE, Discontinued in 2015
Did not find out if it is the same in other vehicle models