Stevo F Posted August 3, 2019 Share Posted August 3, 2019 I was getting my son’s Legacy cleaned and ready to return to him today, after getting a new set of tires, and noticed the airbag light now stays on. Never any issues with it before and no accidents or issues with the light before (definitely none in the 2+ years we’ve owned it). Could a simple tire replacement have triggered it in any way? (no connection between the two that I can think of). Any electrical connections I can see look tight and no work has been done in or around the dash area recently. What else can we check on our own or should we bring it to someone who can scan the code? My scanner only does ECU codes. I hate to return the car to him with this issue (he is at college an hour away). Ironically he has been driving my other son’s Honda for which I have an appointment to have it’s 3rd airbag inflator recall done), so I need to get car back from him when he comes over later today. Quote Link to comment Share on other sites More sharing options...
el_freddo Posted August 3, 2019 Share Posted August 3, 2019 Not an abs sensor issue on one of the wheels? But then again I guess that would have an ABS light for that sort of thing. I hope it’s an easy fix. Cheers Bennie Quote Link to comment Share on other sites More sharing options...
Stevo F Posted August 28, 2019 Author Share Posted August 28, 2019 My mechanic's fancy SRS scanner couldn't read it so he told me to try the diagnostic per the link below. https://redirect.viglink.com/?format=go&jsonp=vglnk_156703159047716&key=c1ac8fd132f1c1d959d5f77155b0d5a6&libId=jzvu7j47010006ha000DAnnprml7o&loc=https%3A%2F%2Flegacygt.com%2Fforums%2Fshowthread.php%2F98-gt-airbag-light-279773.html&v=1&opt=true&out=https%3A%2F%2Fcodes.rennacs.com%2FSRS-Airbag%2FJapanese-Korean%2FSubaru-Airbags.php&ref=https%3A%2F%2Flegacygt.com%2Fforums%2Fforumdisplay.php%2Fsecond-generation-legacy-1994-1998-95.html%3Fs%3D342d2aef37be4c004ef3e837beba015a%26&title=‘98 GT airbag light - Subaru Legacy Forums&txt=https%3A%2F%2Fcodes.rennacs.com%2FSRS-Airbag...ru-Airbags.phpAfter some looking around under the dash I finally located a black plug that matched one of the pictures. I grounded pin 1, per the instructions, and I was able to extract error code # 12, The descriptions I found were:"This Relates to Driver's airbag or control module circuit faults", which seems pretty vague. I Googled the code number and came up with this: "Airbag Main Wiring Harness, Module Wiring Harness Or Roll Connector Open"So are these descriptions saying code # 12 means I should replace he control unit? Used ones seem fairly plentiful on Ebay for not a lot of money. Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted August 29, 2019 Share Posted August 29, 2019 I reviewed the diagnostic procedures for code 12...... Suffice to say that you can't diagnose this. Looks like there's a small tool box full of diagnostic harnesses and resistors required for the tests. Gonna have to let the dealer take this one. GD Quote Link to comment Share on other sites More sharing options...
Stevo F Posted August 29, 2019 Author Share Posted August 29, 2019 13 hours ago, GeneralDisorder said: I reviewed the diagnostic procedures for code 12...... Suffice to say that you can't diagnose this. Looks like there's a small tool box full of diagnostic harnesses and resistors required for the tests. Gonna have to let the dealer take this one. GD I'm wondering if it wouldn't be a better idea to replace the SRS computer with a used one at this point, as I imagine the $50 I spend is less than the dealer will charge just to diagnose the problem Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted August 29, 2019 Share Posted August 29, 2019 (edited) I haven't seen the computers (there's one for each bag) go bad. If the area you live in is prone to rust it may be wiring related. Also the clock spring would be the most likely failure point as that is the interface with the 300 lb gorilla. Does the horn work? GD Edited August 29, 2019 by GeneralDisorder Quote Link to comment Share on other sites More sharing options...
Stevo F Posted August 29, 2019 Author Share Posted August 29, 2019 56 minutes ago, GeneralDisorder said: I haven't seen the computers (there's one for each bag) go bad. If the area you live in is prone to rust it may be wiring related. Also the clock spring would be the most likely failure point as that is the interface with the 300 lb gorilla. Does the horn work? GD From what I've seen, there is just one module for the airbag system on the '98's (mounted on the hump directly below the radio). The horn works fine so I doubt it's the clock spring (I'm assuming there would be a separate code for that, but maybe not for those years). I was actually hoping it was the clock spring since I already have a spare. It's always been a Maryland/ Virginia car with little rust anywhere. Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted August 29, 2019 Share Posted August 29, 2019 So yes there is only a single module. My diagrams were talking about the sensors - there's 4 impact sensors. I doubt it's the computer because that's what's sending out the code. It's probably sensing a wiring fault. These SRS sensors monitor the wiring for resistance. To the point that if a different resistance is sensed you have to replace the harness - repairing them will change the resistance and the computer will not accept it. GD Quote Link to comment Share on other sites More sharing options...
idosubaru Posted August 31, 2019 Share Posted August 31, 2019 Maybe a connector got wet cleaning? Let it dry and maybe you’ll get lucky I doubt its the air bag computer as well but I guess we don’t know. Used to be able to get both bags and the computer as a set for less than a $100 from yards and eBay, I’ve rebuilt some wrecked ones in the past and there isn’t much to it. Supply is way outstripping demand by this point should be some inexpensive sets. If it’s wiring that’ll be a 4 digit debacle at the dealer and good chance they get it wrong the first time. They wouldn’t even take a 98 seriously around here, they probably haven’t seen one in at least 5 years, some of the techs have probably never worked on one. Haha. 1 Quote Link to comment Share on other sites More sharing options...
Stevo F Posted January 3, 2020 Author Share Posted January 3, 2020 I got it to go away by unplugging and replugging the plug under the driver's seat a few times, but now the light randomly came back on yesterday. I've unplugged and replugged the connector under the driver's seat numerous times to no avail. I'm thinking there may be damage to the wires at the plug. Would there be any harm in just cutting the plug out entirely and attaching a couple of spade connectors to the wires (there are just 2 wires feeding in to this connector on this car) so the wires could still be disconnected if the seat were to be removed? Are there any safety or legal concerns in doing a repair like this? Would I have to get a replacement plug like what's under there instead of the spade connectors. I hesitate to do the spade connector fix as I haven't read about many people doing that as a fix for this problem (seems almost to simple a fix, so maybe I'm missing something). I'd like to fix it this weekend as my son would like to take the car back to college, but I'll need to have him take a different car unless this is fixed, and fixed permanently. Quote Link to comment Share on other sites More sharing options...
Rampage Posted January 3, 2020 Share Posted January 3, 2020 G: TROUBLE CODE 12 DIAGNOSIS: Airbag main harness circuit is open. Driver’s airbag module harness circuit is open. Roll connector circuit is open. Airbag control module is faulty. CAUTION:Before performing diagnostics on airbag system, turn ignition switch “OFF”, disconnect battery ground cable and then wait at least 20 seconds. I got the FSM here. https://sl-i.net/FORUM/showthread.php?18087-Subaru-Factory-Service-Manuals- When you click the Green button to download, a new window will open, just close it. Save the zip file to a folder like Legacy 1998 and Unzip the file into that folder. I use 7 Zip, but windows will do it too. Look in Diagnostics--Supplemental Restraint System, also in the Wiring Diagram. One thing you could do is compare seat to seat. Unplug both seat connectors. Do not probe the connectors from the harness. Check ohms on the connectors from the seats. It looks like the sensor has a resistor that is shorted by a switch when there is weight on the seat. Wiggle the wire and see if the reading changes. In order to probe the harness disconnect battery neg. and all the plugs must be removed from the module. The diagrams will give you pin numbers and wire colors on the connectors. Quote Link to comment Share on other sites More sharing options...
Stevo F Posted January 5, 2020 Author Share Posted January 5, 2020 (edited) On 1/3/2020 at 10:12 AM, Rampage said: G: TROUBLE CODE 12 DIAGNOSIS: Airbag main harness circuit is open. Driver’s airbag module harness circuit is open. Roll connector circuit is open. Airbag control module is faulty. CAUTION:Before performing diagnostics on airbag system, turn ignition switch “OFF”, disconnect battery ground cable and then wait at least 20 seconds. I got the FSM here. https://sl-i.net/FORUM/showthread.php?18087-Subaru-Factory-Service-Manuals- When you click the Green button to download, a new window will open, just close it. Save the zip file to a folder like Legacy 1998 and Unzip the file into that folder. I use 7 Zip, but windows will do it too. Look in Diagnostics--Supplemental Restraint System, also in the Wiring Diagram. One thing you could do is compare seat to seat. Unplug both seat connectors. Do not probe the connectors from the harness. Check ohms on the connectors from the seats. It looks like the sensor has a resistor that is shorted by a switch when there is weight on the seat. Wiggle the wire and see if the reading changes. In order to probe the harness disconnect battery neg. and all the plugs must be removed from the module. The diagrams will give you pin numbers and wire colors on the connectors. Thank you. The FSM is very helpful. I was able to pull, the error code of 12 again (I found the two wires with pins attached wrapped up in the wiring under the dash). Plugging one pin into slot one on the connector will generate the error codes and plugging in the second pin into slot # 2 when the air bag light is blinking the codes will clear stored codes. Unfortunately mine didn't clear so the code is still active. For the seat to seat comparison, are you thinking of connecting the ohmmeter between the the connectors under each seat? The only issue there is that there is ony a connector under the driver's seat on my '98 and no wiring under the passenger's seat, so i don't have a second connector to connect it to. Also, is the roll connector the same as the clock spring? If so, I've had others suggest a broken clock spring is one of the most common problems and the roll connector is a possible cause for code # 12. The problem I see is getting a more detailed diagnosis. I was discussing it with a family friend who used a to bew Subaru mechanic (and still works on a number of them) who I'm hoping can help me pin down the exact cause. Edited January 5, 2020 by Stevo F Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted January 6, 2020 Share Posted January 6, 2020 As I said quite some time ago - you can't essily do the diagnostic on this. First of all you don't have the diagnostic harness/resistor kit. And second Subaru doesn't publish the specifications for harness resistance, etc. They rely on the diagnostic kit and a detailed procedural plan that will allow the bearer of the kit to find the fault. The only way forward would be to do a lot of comparative analysis between different circuits of the system or a similar model that's functional. Beyond that you're pretty much going to be doing parts swapping. GD 1 Quote Link to comment Share on other sites More sharing options...
Rampage Posted January 6, 2020 Share Posted January 6, 2020 One thing about probing Air Bag circuits or any circuit with control modules is, you need a low voltage ohm meter. A lot of ohm meters use too high a voltage on the probes and can damage the electronics. I have two VTVMs (Vacuum Tube Volt Meters) for testing sensitive circuits. The one picture shows the Roll Connector in the steering wheel wired to the air bag, so I guess it would be the clock spring. If the plug under the seat is yellow, then it goes to the Inflator which would be the side air bag. That same picture shows the same system on the passenger side, but it could just be an option. I have never had to probe an air bag and I don't know how sensitive they are to voltage. The only thing I know for sure about air bags is they stink when they go off. GD has the right idea. Without the diagnostic harness and resistor kit, your only option would be to unplug the module and 4 air bags and then probe the sensors and wires between connectors. Quote Link to comment Share on other sites More sharing options...
uniberp1 Posted January 6, 2020 Share Posted January 6, 2020 It's the clockspring. Quote Link to comment Share on other sites More sharing options...
Stevo F Posted January 6, 2020 Author Share Posted January 6, 2020 4 hours ago, uniberp1 said: It's the clockspring. I actually have a spareclock spring from my '98 wagon. Is there a wayt to access the connectors to the clockspring without having to pull the steering wheel (like by removing the steering column molding). I'd like to find an easier way to connect up my spare clockspring and see if the code goes away. Quote Link to comment Share on other sites More sharing options...
el_freddo Posted January 6, 2020 Share Posted January 6, 2020 Stevo, it’s steering wheel off for a clock spring swap Cheers Bennie Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted January 7, 2020 Share Posted January 7, 2020 (edited) Nope. Have to pull the wheel. You can't modify the harness, and the connector is not accessible without pulling the wheel off. And yeah - comparative testing should probably be performed with a lab scope on this one. Similar (apparently working) circuits in the same car, or a functional similar model. Or take it to a competent dealer with the testing kit. GD Edited January 7, 2020 by GeneralDisorder Quote Link to comment Share on other sites More sharing options...
el_freddo Posted January 7, 2020 Share Posted January 7, 2020 6 hours ago, GeneralDisorder said: Or take it to a competent dealer with the testing kit. Is there really such a thing these days out side of regular maintenance programs at dealers?? If there is, it’d probably cost more than the value of the car Cheers Bennie Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.