2003 G35 Airbag Light is Constant On (Not Blinking)

[sck2000e]

Second time this has happened. First time, over a year ago, took car to a dealer who ran CONSULT. They could find nothing wrong and turned off the light. The light stayed off until just recently (about 10K miles of driving). This time took to another dealer (different dealer in a different state) who again ran CONSULT. This time dealer results stated "CONSULT test shows DTC B1134 - open driver's side air bag module circuit". The suggested correction was "Airbag system diagnosis found to have open LH side module. Recommend replacement. $758.00" From their wording it's unclear to me whether they are talking about the side airbag module on the door pillar or the main bag. They also verbally told me that if after changing out the module itself and finding that's not the problem, they will have to change harnesses as well and that will be extra. Not wanting to get into a "let's change a part and see if that fixes it" situation, I declined repair until I can do further research.

This car has a history that affects the diagnosis and my decision. My son rebuilt it about a year and a half ago as a low mileage (33K miles) freshwater flood salvage title. There's no evidence of a wreck that would have deployed any of the bags. As a preventive measure during the rebuild he changed out (using junkyard parts) the ECM, BCM, Airbag Module and all other lower body electronics that might have been damaged. He stripped and boraxed the lower interior and took care to clean up all connections, as best he could, with electrical contact cleaner,etc. [Yeah, I know - the purists out there will chide us for dealing with a flood vehicle and for using junkyard parts but for the major $ we have saved, I'll deal with the occasional electrical gremlins that pop up.] The car now has 44K miles and has performed flawlessly except for this intermittent airbag light problem and one recent minor problem with the interior map light (another dose of contact cleaner on the electrical connectors going into the BCM quickly fixed that).

With this history, I'd like to exhaust my options before going back to the dealer. I STRONGLY suspect the problem is just a corroded pin in one of the SRS circuit harnesses and, after the latest CONSULT, I now have the problem isolated to the driver's side. Since the dash light is constant on and not blinking, I suspect the open circuit is probably NOT a defective module but rather just a bad connection. [I've dealt with lots of boat trailer light problems in a saltwater environment and this sounds similar.] Logic also tells me that the affected harness/connector is low in the car since the water didn't get that high. I'm guessing the harness that leaves the console located airbag sensor and that goes off under the carpet that's under the driver's side seat may be the culprit. Before starting with something drastic, and expensive, like changing out modules, I'd like to chase down the airbag circuit connectors (yellow) low on the driver's side and try the contact cleaner trick. I'd really appreciate a second opinion from someone with experience on this type problem before I do so.

Can someone (experienced only please since this is a safety item) either confirm I'm on the right track or stop me before I step off into something I can't handle? I know to disconnect the negative battery terminal for at least (30?) minutes before starting the process. Anything else I should know or be cautious of? I plan to remove the driver's side seat for access - and start there. Given the dealer diagnosis quoted at the beginning, does anyone know which specific module they are talking about? Is there anything like a module/sensor under the driver's seat that I'm not aware of or is that just the harness routing to get over to the side of the car?

Thanks in advance for your help!

[SteveTheTech]

Hey there Steve Welcome to Nico!

While I cannot advise working on the Airbag circuit. If you are going to go for it make sure the negative cable is removed, as you stated. There are no other modules under the carpet, and the AB they were referring to is the one inside the seat. I would suspect an fault in the circuit as you have mentioned. I will look into this again in the morning and let you know if I find something specific I am not 100% on the circuit layout for the AB. I would say pull the four 14mm bolts from the seat and tip it back and disconnect the connector and check the terminals, I doubt you will see anything I would still clean them thoroughly.

The AB system is not typically diagnosed unless you have some type of issue like this but you Must be careful not to supply any form of power to an airbag module.

[sck2000e]

Thanks for the quick response, Steve. I took your advice and, after disconnecting the negative battery terminal, I pulled/tilted the front seat to gain access. Then I separated every connector terminal that was visible on the bottom of the seat and saturated all contacts with spray type electrical contact cleaner. For good measure, I also accessed and did the same thing to all three connectors going to the aibag sensor module located under the center console. Buttoned everything back up, crossed my fingers and started the car . . . and the light is still on. Evidently either the spray cleaner wasn't thorough enough or the problem is with something other than the visible connectors. You said the airbag module in question is located in the seat (thanks, I didn't know that and learned something new). Is it visible, i.e. mounted on the bottom of the seat or is it hidden from view (internal)? What should I be looking for . . . shape color, etc? I saw an approx. 1" x 3" x 6" grayish/white rectangular box mounted on the bottom front of the seat with a single electrical connection going to it (white not yellow connector tab). Not sure what that module does. Also, could there be hidden electrical connectors up inside the seat that I can't see without removing upholstery fabric?

While I may not be able to fix it myself, so far I'm only out a $5 can of contact cleaner and a little time so I'll keep going until I run out of ideas.

Again, thanks for your help!

[SteveTheTech]

Hey there glad to hear you had some luck with the terminals. There are a few things that I should have mentioned before.

First off the airbag module is inside in rear of the seat back. I would leave it alone as it is most likely not your problem. Oh and the box you found is the drivers seat control unit it controls the ADP functions.

Secondly there are two separate levels of DTC detection in the airbag system. The first is current faults and there is a second one for past DTCs. Check out the section of the ESM I have attached below to clear the memory. This may take a few tries to get it right.



Good Luck let me know how it turns out for you.

[sck2000e]

Hey Steve,

It's comforting to hear that you agree the airbag module itself is likely not the problem. As I said in an earlier post, I see no indication that any of the airbags have ever been triggered and the location you describe is much too high up to have been affected by floodwaters based on the residual evidence when my son first got the car. That reinforces by belief that I'm dealing with a corroded electrical connector problem, somewhere low in the car. I really don't know what else to do at this time except what I've already done with the connector cleaner on the terminals.

Thanks for the info on how to attempt to reset the system without having to go back to the dealer's CONSULT program (another $95 just to hook it up). I tried the DCT reset procedure using the ignition switch ON/OFF method but still couldn't get the light to turn off. Perhaps, since the airbag light is constant on and not blinking, I couldn't get the described ON/OFF timing sequence right. I tried to time it using the ABS and VDC lights (which go off a few seconds after ignition ON) but that didn't work. I also tried timing it with the AT Check light which stays on even a few more seconds but that didn't work either. I'll keep playing with it. Although a nusiance, I can live with the airbag dash light staying on if it's likely the system is functioning properly.

My son had another thought. He said that he'd heard that the airbag sensor module can develop a "memory" if the airbags have ever been deployed. Remember, he replaced that sensor with a junkyard part and we obviously don't know the history on it (e.g. maybe it came out of a wrecked car where the airbags deployed?). If that were the case though, why would the light have stayed off for months at a time after being turned off? Anyway . . . aren't electronic gremlins a pain!!!???

Again thanks, you've been very helpful and I really appreciate your comments.

[maxnix]

Here is where mere contact cleaner is not sufficent when compared to Stabilant 22.

Read here:

zerothread/151455

[qship96]

I wouldnt rule out any/every electrical connection high up in the interior of the car. When the inner harbor of baltimore flooded I saw tons of cars that had maybe 1 foot of water in them, but due to their windows being closed and the heat from the sun, condensation on every interior window and what must have been steam room like 100% humidity affecting every square inch of these cars interiors and electronics

[sck2000e]

Thanks for the tip, Brian . . . I'll check into it. I did look at the Stabilant website (Tech Note #2) and saw that they actually advertise the product as a connectivity enhancer and lubricant, not a cleaner. Because I suspect minor corrosion inside the connectors, shouldn't I consider using a good cleaner before I apply the Stabilant 22? I've only used the standard off-the-shelf CRC brand product from the auto parts store. Is there a better connector cleaner out there that I should use before applying the Stabilant 22?

[sck2000e]

Good point qship96. From the CONSULT diagnosis described in the first post, do you know of any other areas on the driver's side that I should be opening up to check? I've already cleaned the connectors under the driver's seat and the 3 going into the airbag sensor module located in the console.

[qship96]

I would obtain the factory service manual that shows the detail and location of every wiring harness and trace them to look for issues.

[fixer]

the air bag light is on and not blinking means that there was a fault in the airbag system but has gone away. the light will not go off unless you clear all dtc with a scanner. only if the light is blinking is when it detects a current fault. even if repairs are made. the light will stay on. the problem you have may be intermitent. there is only one yellow connector under the drivers seat. the remaining harness goes to the side airbag module in the seat back. if you cleaned the connector, this is the only place where there can be a bad connection. other than the plug for the center diag unit( airbag control unit).

[SteveTheTech]

My son had another thought. He said that he'd heard that the airbag sensor module can develop a "memory" if the airbags have ever been deployed. Remember, he replaced that sensor with a junkyard part and we obviously don't know the history on it (e.g. maybe it came out of a wrecked car where the airbags deployed?). If that were the case though, why would the light have stayed off for months at a time after being turned off? Anyway . . . aren't electronic gremlins a pain!!!???

The airbag would have a either an open circuit detection or deploy fault if they had been triggered. The airbag system has very specific diagnostic codes and diagnosis is pretty much straight forward. The circuit integrity must be verified, although risky in this system. Wiring diagrams are located in the ESM and if the each leg is isolated and continuity is verified then you can rule out a short in the wiring. A component failure is not unheard of, and there is a possibility of water intrusion corroding the sensitive detonation wiring.

If you are unable to clear the codes using the key cycle method then the only way to correctly verify the repair is to run the Consult on it yet again.

~Qship The only Airbag related connector that is higher than the door handle is the curtain one (if equipped).

I've only used the standard off-the-shelf CRC brand product from the auto parts store. Is there a better connector cleaner out there that I should use before applying the Stabilant 22?

Many commercially available products have similar active ingredients basically Isopropel Alcohol and CO2, Stabilant uses a polymer type agent to adhere the contacts, I have used a very similar product as well as various cleaners, and they all have their benefits but improving continuity in a circuit (if the terminals are at proper fit and free of contaminants) you resistance reading should be <0.1 ohms from end to end.

I think the spray with a fast drying rate and low grease content should be ideal for what you are working on here.

[sck2000e]

the air bag light is on and not blinking means that there was a fault in the airbag system but has gone away. the light will not go off unless you clear all dtc with a scanner. only if the light is blinking is when it detects a current fault. even if repairs are made. the light will stay on. the problem you have may be intermitent. there is only one yellow connector under the drivers seat. the remaining harness goes to the side airbag module in the seat back. if you cleaned the connector, this is the only place where there can be a bad connection. other than the plug for the center diag unit( airbag control unit).

Thanks for the response, Fixer. I wonder why the service guy at the dealer didn't tell me that a constant on light means the problem has already gone away and just needs to be cleared from the system memory? Apparently he could have just reset the light for me using CONSULT while I was in that first time. Instead, he charged me $95 for the CONSULT hookup, left the light on and suggested that I come back and spend another $758 plus to fix what now sounds like was only an intermittent bad connection. Not that I've re-cleaned all the connections, I'm going to assume that the circuit problem is fixed. I've heard that CONSULT is the only scanner system that can be used on the airbag system. Since I sure don't feel like paying him another $95 just to turn off a light (that he could have done the first time) I'll just live with the light.

[maxnix]

You really dodn't want to do that as you will not know if a component has failed, nor will you pass any state inspection nor likely be able to sell it in the future.

Might as well repair it now and enjoy the benefits. Try another dealer. There are 5 in Atlanta.
Modified by maxnix at 12:44 PM 11/20/2008

[SteveTheTech]

the air bag light is on and not blinking means that there was a fault in the airbag system but has gone away. the light will not go off unless you clear all dtc with a scanner. only if the light is blinking is when it detects a current fault. even if repairs are made. the light will stay on. the problem you have may be intermitent. there is only one yellow connector under the drivers seat. the remaining harness goes to the side airbag module in the seat back. if you cleaned the connector, this is the only place where there can be a bad connection. other than the plug for the center diag unit( airbag control unit).

That's not exactly true. If the light is on steady it means the Diagnostic Control Unit detects a deployed airbag or has a serious fault, here is a quote from the ESM. If the light is flashing it could either mean that the code is present or stored in past memory. I really wasn't sure about that so I had to look it up myself.

So my guess is one of the junkward parts you installed was deployed already. That however does not explain the seat AB code.



Any update from OP?

[sck2000e]

That's not exactly true. If the light is on steady it means the Diagnostic Control Unit detects a deployed airbag or has a serious fault, here is a quote from the ESM. If the light is flashing it could either mean that the code is present or stored in past memory. I really wasn't sure about that so I had to look it up myself.

So my guess is one of the junkward parts you installed was deployed already. That however does not explain the seat AB code.



Any update from OP?

Hey Steve,

Thanks for checking the ESM for me. I don't have access to that.

I agree with your intuition that, because the replacement junkyard sensor unit MAY have come from a car where the bags were deployed, it may be suspect. No way to tell I guess. (While, the BCM and ECM were also replaced with junkyard parts, I don't imagine they have anything to do with the SRS system.)

Still a big question for me is why the light stayed off for almost 10,000 miles after it was intially turned off. (I may not have clarified in my earlier posts but right after the rebuild, CONSULT was run the first time to get all the computers talking again and the light was turned off then.) The light stayed off for for 9+ months and just recently came back on again. Would the light stay off that long if the sensor unit was sending out an an "airbag deployed "code? Remember the most recent CONSULT code is for an "open circuit" on the driver's side and isn't really specific about where. Couldn't that also mean a problem other than with the sensor unit or the airbag module itself? Maybe something within the wiring circuit? Confusing (at least for me)!

The pictures from the ESM manual were VERY helpful. If I'm reading them correctly, the top one applies to a blinking light and the bottom one is for a constant on light. If that's true, for a constant on light, the SRS-51 reference is for a collision diagnosis and the SRS-37 reference is for any of 3 other identified troubles within the warning lamp circuit. Since my light is not blinking, does that rule out SRS-21, a malfunctioning system that needs repair?

Also, since there is no evidence of an earlier collision on THIS vehicle that might have deployed the bags or seat belt pre-tensioner, would SRS-51 even apply? (unless the sensor memory problem can maybe also result in a constant on light as well as a blinking light?) That would leave as the most likely culprit the last option, SRS-37, other troubles that cause a constant on light. Do you think the most recent "open circuit' code might be caused by one of the 3 listed problems associated with SRS-37?

Following that logic, wouldn't (1) a defective sensor unit show up as it's own code on the recent CONSULT? That leaves (2) problems in the airbag power supply circuit or (3) problems in the SRS warning lamp circuit? Shouldn't I have already addressed (2) by cleaning all the circuit connectors on the drivers's side? That would then leave (3) the warning lamp circuit.

Stranger things have happened in my past. My wife had an Oldsmobile wagon in the mid 1980s that got three brand new ECM computers from three different dealers while trying to correct a Service Engine Light (under warranty of course or I couldn't have afforded it, LOL). A wise old service tech at the 4th dealer sensed that wasn't right and finally, correcly identified the problem as a short in the dash warning light bulb. Could my current problem be something as simple as this? I sure don't want to have to pay for another 'let's change out parts and see if that works' program at the dealer.

Sorry for rambling on so. I tend to think out loud sometimes and, by doing so, maybe someone can see if anything I've said here sounds logical.

Again I really appreciate the all the help and feedback!

PS: You asked at the bottom . . . "Any update from OP?" I'm not really sure what you mean by OP.

[SteveTheTech]

Following that logic, wouldn't (1) a defective sensor unit show up as it's own code on the recent CONSULT? That leaves (2) problems in the airbag power supply circuit or (3) problems in the SRS warning lamp circuit? Shouldn't I have already addressed (2) by cleaning all the circuit connectors on the drivers's side? That would then leave (3) the warning lamp circuit.

PS: You asked at the bottom . . . "Any update from OP?" I'm not really sure what you mean by OP.

1- True-but the diagnostic logic only detects open or short circuits in this system not sensor failures and most repairs are merely blind guesses. (This pertains only to this system, for the topic of conversation)

2-True-however a failure in a power supply circuit to the airbag control module would most likely generate multiple unrelated open/failure codes, or generate a low voltage or control circuit open code.

3-The warning lamp circuit is a controlled circuit not a control circuit and to the best of my knowledge has no bearing on DTC detection unless the failure is in the signal wire to the combination meter.

Honestly I am stabbing the dark on this without being able to tear into your car I can only wager guesses on this although I do find the discussion very interesting. Complex SRS problems are pretty few and far between and when they do come up people are not usually will to address them.

Oh and the OP refers to Original Poster , forum slang, I had to google it when I was a noob here. Basically I was asking if you had anything new to share with us.

[sck2000e]

1- True-but the diagnostic logic only detects open or short circuits in this system not sensor failures and most repairs are merely blind guesses. (This pertains only to this system, for the topic of conversation)

2-True-however a failure in a power supply circuit to the airbag control module would most likely generate multiple unrelated open/failure codes, or generate a low voltage or control circuit open code.

3-The warning lamp circuit is a controlled circuit not a control circuit and to the best of my knowledge has no bearing on DTC detection unless the failure is in the signal wire to the combination meter.

Honestly I am stabbing the dark on this without being able to tear into your car I can only wager guesses on this although I do find the discussion very interesting. Complex SRS problems are pretty few and far between and when they do come up people are not usually will to address them.

Oh and the OP refers to Original Poster , forum slang, I had to google it when I was a noob here. Basically I was asking if you had anything new to share with us.

I'm pretty amazed that you are able to give me this level of diagnostic detail without "being able to tear into [my] car". I too wish that were possible because you might be able to see something else if you could be more 'hands-on'. I also wish I had direct access to the dealer's CONSULT program and to the tech running it. The way insurance regs force dealers to operate these days, I have to sit on my hands in their waiting room for 3-4 hours and don't even get the chance to talk to the guy actually running the diagostics. At least with more unrestricted access to CONSULT I might be able to try something and then rerun the program to see if that fixed it (since, as you say, most of the repairs on this system end up being "merely blind guesses"). The way things are, that trial-and-error method might get expensive at 3-4 hrs and $95 per visit.

The diagrams from the ESM that you provided in the earlier post appeared to have links to more information. Specifically the "Go To" references, SRS-51 and SRS-37, look promising. Since I don't have reason to suspect a prior collision, I'd be especially curious about anything in SRS-37. Do you know if that section elaborates on how to isolate or test for the three bulleted possibilities?

I too find this discussion and problem solving analysis very interesting. As for me trying anything new (OP), it appears that I may be at a stalemate unless I want to start spending a significant amount of money at the dealer. And, even if they are able to fix it, I wouldn't really learn anything more or get the satisfaction of having solved the problem without their (other than minimal) involvement. Again, thanks for all your help

[SteveTheTech]

I thought I had supplied the link for the ESM in the thread. You can download it Here.

As for your frustration and determination to do this yourself I can relate, the diagnosis process gets pricey and the parts are even more, it's not very fun work for most of the guys. Just giving them the car and returning when it is finished would leave me frustrated, I am a hands on person much like yourself.

If you have the book, some patience and tools and as it appears you do the ambition to this I think you can. Check the esm and see if there is anything you have already done or symptoms that match and we can brainstorm, you can email or im me if you have any questions.

[sck2000e]

Steve,

The link to the electronic service manual proved to be a BIG help . . . many thanks!

I was able to access the srs.pdf and then follow the link for SRS-37, the one that focuses on the 3 possibilities for the constant on light. Of the 3 listed possibilities, I think I was able to eliminate the power supply circuit as a potential problem. The procedure calls for testing proper circuit operation merely by verifying the integrity of the 10 amp fuse in slot 13 of the JB. Verifying integrity of all fuses and relays was the very first thing I did.

Of the other 2 possibilties, I agree with your assesment that "the warning lamp circuit is a controlled circuit not a control circuit and [to the best of my knowledge] has no bearing on DTC detection unless the failure is in the signal wire to the combination meter". While possible, for the reasons you state here, I judge this to be an unlikely cause for the problem.

The remaining possibility involves testing for proper operation of the diagnostic sensor unit, a prime suspect all along. That test procedure requires hooking up CONSULT, which I obviously can't do at home and on my own. However, the procedure says that if you get a CONSULT code, the repair is to replace the senor unit. Of the three listed possibilities, this one seems most likely to me. Possibly the sensor unit that my son had replaced earlier is defective, even if it's only on a marginal/intermittent basis?

Physical replacement of the unit is easy enough since it's very accessible under the center console. Before I do a sensor unit replacement though, I think I'm going to pull the existing one out and and thoroughly clean the input terminals one more time. The last time I did it with the unit installed and I may not have have been able to angle/accurately aim the cleaner's spray nozzle.

Do you have any further thoughts? Do you think that I might me on the right track with this logic trail?

[fixer]

IF YOU LOOK AT SRS30 THERE IS A WAY TO RETRIEVE DTC FROM AIRBAG WITHOUT CONSULT AND IT WILL ERASE CODES.

[sck2000e]

IF YOU LOOK AT SRS30 THERE IS A WAY TO RETRIEVE DTC FROM AIRBAG WITHOUT CONSULT AND IT WILL ERASE CODES.

I looked at SRS30 and it explained how to go into Diagnosis mode using the ignition switch ON/OFF. I've tried that already and it didn't work. [See earlier discussions in this thread].

According to the reprint from the manual provided by SteveTheTech on 11/11/2008, "CAUTION: In User mode, when the "AIR BAG" warning lamp is not blinking, switching to Diagnosis mode by ignition switch operation is not possible." Apparently the manual is right - it's not possible, or at least I could't get that method to work.

Thanks for the response anyway.

[sck2000e]

Sometimes the simplest answer turns out to be the easiest.

Remember that I said that the airbag module had been replaced with a junkyard part? Obvioulsly there was no way to tell whether the module had come out of a car that had been wrecked, airbags blown, etc. I pulled the module, sent to MyAirbags.com (advertises on this site) for a $49 module reset, reinstalled and voila' . . . the light went out. Apparently I was dealing with a previously stored hard code that had to be cleared from the replacement module.

Everyone . . . Thanks for all your help in diagnosing and resolving the problem.

[maxnix]

Code probably deployed when it was removed.

Steve might tell us.