Airbag Component Simulator fabrication

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  • Witsend
    Banned
    • Nov 2012
    • 2942

    Airbag Component Simulator fabrication

    When I worked at a Ford Dealer and got a a car with an airbag light on , some of the codes were related to airbag or seat belt pre tensioner resistance being too high or out of range , and you could disable the system , unplug the pre tensioner, or airbag and plug in a simulator that had a specific resistance to simulate the presence of a good component in the circuit , and if I do recall , I was able to watch WDS resistance or voltage graph change while wiggling the underseat wires leading to a pretension er.

    I'm well aware of the dangers of trying to test an actual individual airbag or pretension er simulator, or the non isolated circuit while detonatable component is still attached to circuit with an ohmmeter , but more in depth information should be available in all wiring diagrams about each manufacturers systems as to what normal internal range of resistance of each component actually should be , so I can either purchase a component simulator or cut the connector pigtail off a spent component and make my own damn airbag or pretension er simulator with a Radio shack resistors soldered in series . If Snap On Compiled a comprehensive list of manufacturer's air bag component resistances in a little book, by model and year and sold a Blue Point box with about 25 different common style connectors and noid light style plug in resistors to make your own airbag system component simulators, it would save a lot of time and headaches. Maybe could even sell a box of common fuel pump connectors too with a loud Fiam horn . Plug it in crank ignition , horn blows
    Last edited by Witsend; 04-15-2014, 05:16 PM.
  • maven
    Senior Member
    • Mar 2014
    • 269

    #2
    Most manufacturers don't supply inflator module resistance values in their service information because they don't want people jamming an ohmmeter into them.....this type of information is largely only available in engineering documents.
    This fact alone notwithstanding you're talking about a massive collection of connectors to accumulate, GM alone has well in excess of 50 inflator module connectors.

    As for the fuel pump connector/horn idea.....get yourself an amp clamp if you wanna spend money. If you're a do it yourselfer or feel the need to disconnect things, fabricate a test lamp with a 5amp draw.

    Comment

    • Witsend
      Banned
      • Nov 2012
      • 2942

      #3
      Air bag component simulator

      Maybe the manufacturers could at least say Restraint code xxx sets when Diagnostic monitor sees circuit resistance going below X ohms and code xxy sets when resistance goes above y ohms, and when testing a proper airbag simulator part # Blah Blah Blah must always be used to simulate a good component. They don't need to post a good component's resistance values, just the high and low threshold that would cause the SRS light to come on . Knowing that range you could make a simulator with a resistance in the middle.
      Last edited by Witsend; 04-17-2014, 09:21 AM. Reason: "It's time to Rev up YOUR engines, not mine unless you want to pay for the core."

      Comment

      • maven
        Senior Member
        • Mar 2014
        • 269

        #4
        Originally posted by Witsend
        Maybe the manufacturers could at least say Restraint code xxx sets when Diagnostic monitor sees circuit resistance going below X ohms and code xxy sets when resistance goes above y ohms, and when testing a proper airbag simulator part # Blah Blah Blah must always be used to simulate a good component. They don't need to post a good component's resistance values, just the high and low threshold that would cause the SRS light to come on . Knowing that range you could make a simulator with a resistance in the middle
        GM for instance again often does give the value at which code is set for too high or too low a resistance in the DTC descriptor. GM also shows deployment loop resistance as calculated by the SDM on many vehicles. This alone is enough to determine if the wiring and sensing is good. induce a short, or a known resistance and you just tested all the wiring and SDM, I rarely find myself wanting to use the SIR load tool that GM provides, and thats free! its a pain to find the proper connector even when the manufacturer is providing them and telling you exactly which to use in their service information.(I cant imagine having to do this for multiple manufacturers) I tend to use as lean a diagnostic approach as possible, minimizing my effort and tool use as possible. It sounds like you have a tool addiction......I feel your pain but I dont think following this one will make you any more productive

        Comment

        • Witsend
          Banned
          • Nov 2012
          • 2942

          #5
          Air Bag System Component simulators

          To follow manufactures precautions for covering their asses I'm too lazy to do it and am even reluctant to have to access a battery and disconnect it to disable an airbag system now a days because of having to reintiallize seats, windows, anti theft codes to enter etc,etc let alone pulling a damn console to pinpoint test a circuit from the air bag module connector with some Fafignuugen VAG breakout box
          If I have a code related to being open or high resistance I Just unplug component and short the harness connector if it don't already have a shorting bar inside it and check for another code related to circuit now being shorted.
          I think Some manufacturer modules would just sh@t out one code for both the circuit being either shorted or open and you still need a circuit load simulator. I figure it still wouldn't hurt to start a collection of clock spring, airbag , pretension er pigtails with leads off of spent components so I can just plug them right in to a harness. Even though there might be 50 different connector styles, you might be able to file off some of the alignment nubs and get with a dozen or so .

          Comment

          • Crusty
            Senior Member
            • Dec 2007
            • 2450

            #6
            Originally posted by Witsend
            To follow manufactures precautions for covering their asses I'm too lazy to do it and am even reluctant to have to access a battery and disconnect it to disable an airbag system now a days because of having to reintiallize seats, windows, anti theft codes to enter etc,etc let alone pulling a damn console to pinpoint test a circuit from the air bag module connector with some Fafignuugen VAG breakout box
            If I have a code related to being open or high resistance I Just unplug component and short the harness connector if it don't already have a shorting bar inside it and check for another code related to circuit now being shorted.
            I think Some manufacturer modules would just sh@t out one code for both the circuit being either shorted or open and you still need a circuit load simulator. I figure it still wouldn't hurt to start a collection of clock spring, airbag , pretension er pigtails with leads off of spent components so I can just plug them right in to a harness. Even though there might be 50 different connector styles, you might be able to file off some of the alignment nubs and get with a dozen or so .
            Maven is right.
            READ the code set criteria and you can figure out what the system wants to see.
            ONE REASON they make it as hard as they do is so people don't HURT THEMSELVES OR OTHERS playing with fire-!!!

            YES, I have substituted a components' resistance value in the circuit for testing purposes, especially with intermittents, BUT I have done so very carefully so as to not possibly induce an airbag deployment.
            Can you imagine how many serious injuries could occur if they just allowed people to willy-nilly plug things into an airbag system-?? They have test sequences to do so safely.
            As for starting a collection, well, substitute with a known good part isn't really diagnostics....it's just plug-N-pray.
            Be careful. These things have a LOT of force. One wrong move and....BANG....at 186,000-miles-per-second.

            Comment

            • maven
              Senior Member
              • Mar 2014
              • 269

              #7
              Wit, if you think starting a collection of connectors, etc. is the quickest way for you to accurately diagnose stuff then go for it!

              Im sure we all make our own tools at some point. I know Ive got a selection of test lights with at least 4 different amperage draws and with probably 5 different GM specific terminals on the end to make my life easier. The 3 minutes it took me to fabricate each one is saved everytime I dont have to do invididual power, ground, or control tests on a circuit or root through the 150+ terminal adapters I have and swap meter leads to use a DMM.
              I just know that if this approach wouldve helped me with SIR issues I wouldve already been doing what youre thinking about. Perhaps you see a lot more problems then I do? I just cant justify the time or potential expense as I know I would never make it back.

              Comment

              • Witsend
                Banned
                • Nov 2012
                • 2942

                #8
                Air Bag Component Simulator

                I doubt if I'll bother collecting too many airbag component pigtail connectors for diagnostics work , but what got me starting the thread , was my frustration in obtaining information for a good friend to make a BST (Battery Safety Terminal) simulator for his 02 BMW X5. I found this link which I think can save him big bucks replacing the entire positive cable to fix the airbag light staying on , but I'm sure friend and hundreds of other owners of old BMW Money Holes would rather just install a circuit simulator and hope the thing just burns and is totalled if wrecked bad enough to cause any sort of electrical fire.

                Comment

                • dlm1
                  Junior Member
                  • Jul 2014
                  • 23

                  #9
                  The BST deal on BMW and other car lines is to Protect the Fireman, Rescue Personnel when they come to Dig your half dead arse out of

                  the car, plus fires etc. I know it seems like a pita to sort thru the info and why/how it works, but my experience has taught me its there for a

                  reason, may be overkill etc but that's
                  not my call.Worth the time it takes to fully understand the system you are attempting to repair. There has been cases of rescue personal being killed and hurt from a active system. Some of these guys cut power and grd cable before they dig in.
                  I will try and enclose a pdf with some info.It is not a complete study, more like a Primer for people reading this thread who want to do the right thing
                  Attached Files

                  Comment

                  • Witsend
                    Banned
                    • Nov 2012
                    • 2942

                    #10
                    I'm sure it could be argued that some car owners will face freezing to death on the side of the road in a blizzard after a minor hit and run fender bender because they can't start the car .
                    What happens if you're in left turn lane and get bumped from the rear , on a rainy foggy evening your BST pops and you roll into oncoming traffic , maybe your airbags are able to still work for up to a minute, maybe not? If your lucky no one is coming A Ford you reset an inertia switch and you're on your way again
                    Those BST's don't exist to save the EMT , or me, the PITA things only exist to protect manufacturers from liability lawyers, because they decided to bury the battery in rear of vehicle under the spare tire near a gas tank.
                    I'm just afraid the Bean counters of American cars are going to adapt this stupidity onto our cars . ACHTUNG! Please just Keep the Farfignuugen gadgets cheap to replace and easy to work on , or folk like me will JUST clean and press it back together and tell Suckers to go spend $1500 at the dealer for a new battery cable, that they don't really need , just to replace the firecracker and resistor pellet part.
                    Also when those things pop if car is still running that $500 plus alternator might just take a dump besides , like my friends X5 did . Kinda like removing a battery cable while car is still running just to see if alternator is putting out really a pretty dumb thing to do.
                    Last edited by Witsend; 07-29-2014, 09:07 AM.

                    Comment

                    • sycotic09
                      Junior Member
                      • Apr 2012
                      • 1

                      #11
                      ohm on airbag systems

                      most air bag systems work at about 3 ohms i made a diagnostic tester from a volume knob for an amp have 4 mounted into a box all parts from radio shack under 30.00 has not failed me yet... just my 2 cents

                      Comment

                      • Witsend
                        Banned
                        • Nov 2012
                        • 2942

                        #12
                        Thanks, having something like the Amp knob you could probably mark the resistance of the knob at certain positions too.Depending on the resistance range maybe you might even be able to test certain gauges with it too.
                        I don't condone bypassing safety features , but the BST on an old Beemer positive battery cable might be an exception versus a thousand dollar battery cable and power distribution harness assembly or even triing to cobble together a BST (battery Safety Terminal ) repair end.
                        Together with a scan tool and a few connectors you could incrementally adjust the resistance up or down until the airbag light stays off after clearing code and or comes back on, and record the results for an acceptable expected resistance of an airbag system component that the manufacturer doesn't post the specs for of the special simulator tool(if they even exist)
                        Last edited by Witsend; 11-13-2014, 11:34 AM.

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