Best way to test the sensor is to plug into the air bag controller. It runs several diagnostics including digital communication that can't be diagnosed with a multimeter. There are many ways an acceleration sensor can fail and still show an acceptable resistance.
Muchas gracias amigo por compartir su conocimiento. Revisare el estado de los sensores de impacto frontales en mi town country 2005, ya que tengo encendida la luz de airbag. Te mando un abrazo desde chile.
Thanks for sharing. But, OL means open loop (infinite resistance) Not Zero resistance. This test will not work for modern impact sensors. They have a small circuit board which holds on it an IC and some transistors.
If all sensors were like that, they shouldn't need replacement. Nothing can go wrong with it. It has 2 resistors on the little circuit board, probably just to limit the current to the airbag control module when it sends the crash signal from those copper tabs that momentarily touch together upon impact. The only other possibility I see is that it is made so a resistor blows, necessitating a replacement sensor. If the value of the blown resistor is known perhaps it could simply be replaced.
Hello brother why you keep saying its 0 ohm while the leads are not connected to anything. You should have said high impedance. Thank you for your video
been awhile but off the top of my head, fairly sure safety circuit/check/arming circuit sends a voltage and it uses an PNP transisor, the arming circuit gives P to the transistor and then the initiating circuit uses the p and n when it deploys, could be wrong though
I have a question. I just found out my side impact sensor is damage on my nissan pathfinder 2012. So i removed it. If i put back the battery connection. Will the airbag deploy?
Found the answer to my question "why is the good senor have resistance, but the bad one OL?" Answer; There is a TEST RESISTOR on the circuit board so one can test the sensor. After activation, the resistor is somehow bypassed (Not sure how).
@@PeterFinnTheCarDoctor Normal sensor reads a resistance of the resistor but when the sensor is activated due to impact the two plates inside the sensor will touch each other sending a short circuit signal to the airbag module tell it the sensor is now activated. Before the activation the airbag module sees a value of resistance but during activated the airbag module sees a short circuit value i.e. zero resistance hence can recognize whether the sensor is healthy ( terminals read a value of resistance or bad (sensor shows a zero resistance (i.e. a short circuit between its two wires) or open circuit (reading OL) on the multimeter.
@@MustafaMustafa-kw2ji So if i'm understanding your last sentence correctly, you're saying there are 2 different ways in which a failed (bad) sensor can show itself; either open circuit (infinite resistance), or short circuit (zero resistance). Do i have that right?
Forgot to ask do you know the resistance of that resistor. Seems to bypass that sensor while waiting for a replacment you could just wire a resistor inline at the pigtail. I had one on a pontiac the other day that is no longer manufactured so I could not get a replacment.
@@dr7477 over load is voltage open load or open loop is continuity. Ol on voltage is a measure of overvolt but ol on ohms setting means open circuit which equates to infinite resistance
@@alan4sure you are measuring a resistance between the two wires regardless of positive or negative. If the resistance value between the two wires have a value the sensor is ok but if the resistance value shows zero ( i.e. short circuit) or OL ( i.e. open circuit, the sensor is bad)
Viewer beware...I found this "How To" to be completely misleading, in my case anyway. I replaced a door on a 2012 Fiat 500 with a salvage door from same year and model. The airbag sensor in replacment door was incompatible and caused "Airbag Failure warning" on the dashboard. Tested it with Ohm meter and it showed "OL" open loop, which this video inicates as "BAD." then I checked the sensor from the old damaged door, it too indicated "OL"..."BAD" WTF! Neither door had been involved in an airbag deployment situation, Did I somehow damage them? So do I try to find a new replacement sensor with the correct part number @ $40-60 and shipping delay? Finally after much internet searching (and soul searching) I just removed the original door's sensor and stuck it into the circuit, and instant cure, no airbag warning. So I believe the info in this video was, in this case, WRONG. "OL" appears to be the normal "Good" reading. Also this is one of many videos describing "how a sensor works'' showing a tiny hammer-like swinging part which causes a momentary contact of two copper blades etc.Well, NOT NECESSARILY. My Fiat's door sensor is an air pressure type sensor, I figured this out myself and finally had it confirmed in a Fiat parts diagram. Apparently, a sudden door impact causes a momentary increase in pressure inside the door and the puff of air causes contacts inside the switch to momentarily close. So... if I hadn't seen the video I probably would have saved myself considerable head scratching and self doubt, and a couple of days delay in finishing the job. A learning experience for this amateur mechanic! Your results may vary, who knows?
I always wondered how they worked. Cool video Peter!
Thank You. 😀👍
Great testing Peter with your new excellent meter! Also, sharp knife can be useful sometimes!
Yes, interesting test and Thanks. 👍
Best way to test the sensor is to plug into the air bag controller. It runs several diagnostics including digital communication that can't be diagnosed with a multimeter. There are many ways an acceleration sensor can fail and still show an acceptable resistance.
Muchas gracias amigo por compartir su conocimiento. Revisare el estado de los sensores de impacto frontales en mi town country 2005, ya que tengo encendida la luz de airbag. Te mando un abrazo desde chile.
👍😀
Thanks for sharing.
But, OL means open loop (infinite resistance)
Not Zero resistance.
This test will not work for modern impact sensors. They have a small circuit board which holds on it an IC and some transistors.
Thanks for the info
The impact sensor he tested on had a circuit board and resistors
Correct OL means open loop, so maximum resistance.
Thanks man. I’m Brazilian and your video will help me so much! Sorry my bad english! Bye
Glad to hear that!
muito bom, very good Peter
Great Work 👍
Welcome, can I ask for your help to explain to me the malfunction code B1334 for 2012 Kia Cerato
Such creativity is needed in Cameroon
👍
Thank you , I am gonna test the sensor on my Chevy Express 2010
Glad it helped
And????
If all sensors were like that, they shouldn't need replacement. Nothing can go wrong with it.
It has 2 resistors on the little circuit board, probably just to limit the current to the airbag control module when it sends the crash signal from those copper tabs that momentarily touch together upon impact. The only other possibility I see is that it is made so a resistor blows, necessitating a replacement sensor. If the value of the blown resistor is known perhaps it could simply be replaced.
Noted 👍
Hello brother why you keep saying its 0 ohm while the leads are not connected to anything. You should have said high impedance. Thank you for your video
If the mechanism of the sensor is similar,then can I substitute for other sensors,?
For example, replacing bmw sensor with chevy sedans?
Peter
Do you work as car repair guy in some car service?
Or you do this as a hobby in your garage?
Hello, I read Your comment. Thanks. 👍😀
been awhile but off the top of my head, fairly sure safety circuit/check/arming circuit sends a voltage and it uses an PNP transisor, the arming circuit gives P to the transistor and then the initiating circuit uses the p and n when it deploys, could be wrong though
Thanks for info 👍👍
I have a question. I just found out my side impact sensor is damage on my nissan pathfinder 2012. So i removed it. If i put back the battery connection. Will the airbag deploy?
I have read your post! Good comment. Continue in the same way.👍😀
Found the answer to my question "why is the good senor have resistance, but the bad one OL?"
Answer; There is a TEST RESISTOR on the circuit board so one can test the sensor. After activation, the resistor is somehow bypassed (Not sure how).
Noted
@@PeterFinnTheCarDoctor Normal sensor reads a resistance of the resistor but when the sensor is activated due to impact the two plates inside the sensor will touch each other sending a short circuit signal to the airbag module tell it the sensor is now activated. Before the activation the airbag module sees a value of resistance but during activated the airbag module sees a short circuit value i.e. zero resistance hence can recognize whether the sensor is healthy ( terminals read a value of resistance or bad (sensor shows a zero resistance (i.e. a short circuit between its two wires) or open circuit (reading OL) on the multimeter.
@@MustafaMustafa-kw2ji So if i'm understanding your last sentence correctly, you're saying there are 2 different ways in which a failed (bad) sensor can show itself; either open circuit (infinite resistance), or short circuit (zero resistance). Do i have that right?
How did you determine that the sensor had to be tested in the first place?
Noted
Ol means no continuity. Also know as a open load. That is not the same as no resistance .
Thanks ! 👍😃
Forgot to ask do you know the resistance of that resistor. Seems to bypass that sensor while waiting for a replacment you could just wire a resistor inline at the pigtail. I had one on a pontiac the other day that is no longer manufactured so I could not get a replacment.
OL means over load not open load. Over load meaning there is more resistance than can be measured by the meter
@@dr7477 over load is voltage open load or open loop is continuity. Ol on voltage is a measure of overvolt but ol on ohms setting means open circuit which equates to infinite resistance
Infinite resistance.
On the first sensor since the wires weren’t color coded how did you know which one positive?
The inside parts lead one to think it doesn't require positive or negative specific connection, it is just a switch.
@@alan4sure you are measuring a resistance between the two wires regardless of positive or negative. If the resistance value between the two wires have a value the sensor is ok but if the resistance value shows zero ( i.e. short circuit) or OL ( i.e. open circuit, the sensor is bad)
@@MustafaMustafa-kw2ji which means it acts exactly the same as a switch. Either open or closed.
"0L" means "open line" anyway thank you for the video
Thanks
How to know negative and positive wire?
Noted
The connector could be bad and not the sensor. Test the sensor when it is disconnected from the connector.
Thanks for comment. Glad to hear that 😊👍
Two! Two sensors! Ha. Ha. Ha.
👍
And I love to count. Ha ha ha!
how test shiled air bag
Good comment 👍😀
Viewer beware...I found this "How To" to be completely misleading, in my case anyway. I replaced a door on a 2012 Fiat 500 with a salvage door from same year and model. The airbag sensor in replacment door was incompatible and caused "Airbag Failure warning" on the dashboard. Tested it with Ohm meter and it showed "OL" open loop, which this video inicates as "BAD." then I checked the sensor from the old damaged door, it too indicated "OL"..."BAD" WTF! Neither door had been involved in an airbag deployment situation, Did I somehow damage them? So do I try to find a new replacement sensor with the correct part number @ $40-60 and shipping delay? Finally after much internet searching (and soul searching) I just removed the original door's sensor and stuck it into the circuit, and instant cure, no airbag warning. So I believe the info in this video was, in this case, WRONG. "OL" appears to be the normal "Good" reading. Also this is one of many videos describing "how a sensor works'' showing a tiny hammer-like swinging part which causes a momentary contact of two copper blades etc.Well,
NOT NECESSARILY. My Fiat's door sensor is an air pressure type sensor, I figured this out myself and finally had it confirmed in a Fiat parts diagram. Apparently, a sudden door impact causes a momentary increase in pressure inside the door and the puff of air causes contacts inside the switch to momentarily close. So... if I hadn't seen the video I probably would have saved myself considerable head scratching and self doubt, and a couple of days delay in finishing the job. A learning experience for this amateur mechanic! Your results may vary, who knows?
Noted. Fiat issue
OL= open loop
Thanks 👍😀
@@PeterFinnTheCarDoctor actually thank you, I didn't know that until I looked into what it was. So thank you.
OL is not zero it is Open lead meaning resistance is too high to read or open
Noted