i figured it was worth a shot. i have a pair of both. i just have to get around to putting them in lol. i dont think wattage makes a difference either but i figured it was worth a try.

 

You might as well take a shot at it. If nothing else they are not expensive to get if the ones you have don't work.

 

The higher wattage resistor will be able to handle higher current without overheating and possibly damaging the resistor. Did the 2.2 ohm 1/4 watt resistors ever work for you? If so, I guess it's possible that your 1/4 watt resistors simply overheated and burnt out. So if that's the case, then the 2.2 ohm 1/2 watt resistors should fix the issue.

 

All of my resistors were 1/2 watt. The issue was that the 4.7 ohm resistors would only work for a short period of time. The 2.2 ohm seem to be working ok.

 

Yeah, it doesn't need to be the exact same resistance as the original air bag, but it does need to be close... Too little resistance and it won't think the air bag is there and too much resistance and it will think it's a bad air bag.

 

Well, well, well, look who's back- it's the airbag light. It started flashing again on Saturday. I have been airbag light free for about 5 months now and I have had the passenger seat emulator installed for about 3 months. I wonder if it is the resistor or the emulator that is causing the issue. I did the reset with the on button last night. This morning it flashed slowly and the second time I started the car it remained off. Hopefully, it stays off.

 

Well, it has been a week and no return of the airbag light after the reset so hopefully it was just a fluke.

 

I knew I spoke too soon. The airbag light came back on at the end of last week and now when I reset it the light comes back on more and more often. So I probably need to replace the resistor AGAIN...

2GorNot2G- Do you know what brand of resistor you use? These things just don't seem to last. I am seriously contemplating putting an ohm meter on the wire ends of the factory seat to test the actual resistance so that I can get the right resistor for sure. Everyone seems to tell me not to for fear of setting off the airbag. Did you actually do this to make sure you had the right resistor? Thanks!

 

I replaced the resistor on the driver's side the other day and the airbag light went away. I wonder if I need to switch to a better brand of resistors or if I need to measure the actual resistance of my factory seat and hope that the airbag does not go off. 2GorNot2G or has anyone else actually run the resistance on their factory seat without setting off the airbag? I am really hoping to get this figured out before I get a Sparco seat for the passenger side too.

The good news is that I figured out that if I stretch the wiring a bit I can actually change the resistor without having to remove the seat. So this could definitely save me some time if I keep having to replace the resistor every 6 months or so.




The other thing I did was sand down the rust on my custom height seat rail on the outer brackets and repaint them. This was probably due to a combination of the aftermarket paint job, salt in the winter, and having to remove the seat a bunch of times. Hopefully, I just solved at least 2 of the 3 issues.

 

Thanks to 2GoRNot2G's suggestion of moving up to 2W resistors instead of 1/2W resistors, I installed one yesterday on the driver's side. I drove around a lot yesterday and today and it seems to be holding up well, but only more time will tell for sure.

 

W=Current * voltage
W = *current^2) * resistance

Several other variations to the formula too. Figure out the voltage drop across the resistor, the current through it, then get a resistor 2-4x of power consumed. That should give a good margin for heat dissipation.

2.2Ω is very close to a short.

 

The trick is trying to get the right resistor without having to measure the actual current in the oem seat and risk setting off the airbag. Of the very few people who have actually replaced their seats I tried 2.2 ohm and also 4.X. How do you know 2.2 is close to a short without knowing the resistance in the oem seat? Below is what 2gornot2g sent me. Maybe between the 2 of you we can figure this out. Thanks!

"If the resistors keep failing it's completely possible that you are using too low of a wattage resistor. Using Ohm's law, P = I x V (where P is the power in wattage, I is the current in amps, and V is the voltage) you can calculate the amount of current (amps) that a component can safely handle without failing and in the case of your air bag resistor, how much power it can safely dissipate without overheating. Solving for I (amps) the equation becomes, I = P/V... So for a 1/2 watt resistor it would be rated for only .04 amps @ 12 Volts (.50/12 = .04) or ~40 mA, but if you used a 2 watt resistor it would be rated for about 4 times that or .166 amps @ 12 Volts (2/12 = .166666), or ~166 mA. So if the air bag circuit in your G has a current greater than the resistors rating then the resistor will eventually overheat and fail. I'm not sure what wattage resistor you are using, but here's a link for 2 watt, 2.2 Ohm resistor... Might be worth a shot if they keep failing."

 

How do I know... Because any low value resistance results in high current. As indicated, power (wattage) is a product of voltage and current, so say you have a 2Ω of resistance load on a 12 V circuit, that's 6 amps (12V/2Ω); 6*12=72 watts. That's just a basic series circuit example.

In your case, the resistor is going inline to the seat, so there's voltage drop across the resistor and another drop across the remainder of the circuit. While the instrument used to measure the current does affect the circuit slightly, the resistors used would affect it more so.

Do these failed resistors result in an open or short? Do they show discoloration signs of burning (smell?).

You could also indirectly obtain the current. V=IR, so I=V/R. That should be easier to measure. Measure the resistance of the resistor first. Then measure the voltage across the resistor on an energized circuit.

So say R=2Ω, and voltage across it is 2.5V, current then is 2.5V/2Ω or 1.25A (that's still a high amperage). So you'd need a resistor rated at 2.5V*1.25A or at least 6 W (2x margin for safety).

Hope this makes sense.. Goal should be to minimize the current/power across anything additional you add to the circuit (for safety reasons).

 

I was very good at math in H.S. and college and I can turn a wrench on pretty much anything, but I struggle with understanding electronics so bear with me. I am not sure the resistors are actually failing and they show no signs of discoloration or burning. The airbag light just starts flashing after about 4-6 months.

This is the 3rd batch of resistors I have tried on 2gornot2g's suggestion because everyone is afraid of actually measuring the resistance on the oem seats because they think it will set off the air bags. Maybe 2gornot2g's G37 is different than mine somehow because he does not seem to have the same issue. I have not had an issue with these resistors yet, but I would not be surprised if I did 6 months from now.

So are you suggesting I hook leads up to the wires from the car to try to guess the resistance in the side airbag in the oem seat?

 

I don't think just measuring the seat's resistance will give you an accurate reading. I would think the circuit is much more complex than a simple resistive load.

However, since the resistors do seem to work for some period of time, it's worth investigating the voltage across them and current. The former you measure with the circuit energized, the latter you compute based on the resistance you measured before installing them into the circuit using the formula above.