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Old 11-04-2009, 09:19 PM   #1
RedStickHam
 
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Passenger Airbag Question

Today I was driving my wife home from work in my 2009 Yaris hatchback and something happened with the passenger airbag. The light indicated the airbag was on then all of a sudden the light indicated the passenger airbag was off. She unbuckled and rebuckled the seat belt and the airbag was switched back on again.

Can anyone explain what caused the passenger airbag to turn off? Any ideas?

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Old 11-04-2009, 09:48 PM   #2
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maybe a loose switch in the buckle, or on the weight sensor...
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Old 11-04-2009, 10:20 PM   #3
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Originally Posted by severous01 View Post
maybe a loose switch in the buckle, or on the weight sensor...
From experience reverse engineering the passenger occupancy ECU to build my bypass module for people with aftermarket seats, I can say that it's not a loose connector.

The passenger occupancy ECU polls the sensors and the passenger seat belt switch every 100ms. If any of the 4 weight sensors or the buckle switch don't respond, it shuts down and flashes the passenger airbag off light. It won't reset from that state until the ignition is cycled.

For it to have done what you saw, it had to have weighed her as being under the limit for arming the airbag. If she is fairly light and was shifting in the seat or you hit a pretty good bump I could see the system disarming and then rearming the airbag.

Did the passenger seatbelt light come on as well?
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Old 11-05-2009, 09:19 AM   #4
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Quote:
Originally Posted by CTScott View Post
From experience reverse engineering the passenger occupancy ECU to build my bypass module for people with aftermarket seats, I can say that it's not a loose connector.

The passenger occupancy ECU polls the sensors and the passenger seat belt switch every 100ms. If any of the 4 weight sensors or the buckle switch don't respond, it shuts down and flashes the passenger airbag off light. It won't reset from that state until the ignition is cycled.

For it to have done what you saw, it had to have weighed her as being under the limit for arming the airbag. If she is fairly light and was shifting in the seat or you hit a pretty good bump I could see the system disarming and then rearming the airbag.

Did the passenger seatbelt light come on as well?

The seatbelt light only came on when she unbuckled. She did shift around in her seat a little though. One other thing to note was I had stopped the car to empty our mailbox before she did the seatbelt thing, so perhaps it reset with the ignition being turned off and back on.

Thanks.

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Old 08-08-2010, 09:56 PM   #5
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I kind of have a similar problem. I got in my Yaris one day and I noticed the seat belt light was blinking but no sound and the light for passenger air bag off was lite up. There was no passenger in the seat. I have tried sitting in the seat and fastening the buckle to see if the light goes off but no luck. Any ideas or solutions would be appreciated. It's getting annoying.
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Old 08-08-2010, 10:43 PM   #6
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Originally Posted by laer899 View Post
I kind of have a similar problem. I got in my Yaris one day and I noticed the seat belt light was blinking but no sound and the light for passenger air bag off was lite up. There was no passenger in the seat. I have tried sitting in the seat and fastening the buckle to see if the light goes off but no luck. Any ideas or solutions would be appreciated. It's getting annoying.
You can make the SRS system flash the SRS light to tell you what the issue is. You jump the two terminals below on the OBD port (with the ignition off) and then turn the ignition on. The SRS light will then flash in a pattern to indicate the error. The pattern will groups of fast flashes, separated by longer off periods. If more than one DTC is logged, then the codes will be separated by even longer off periods.


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Old 06-22-2013, 09:47 PM   #7
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Clearing DTC after apparently resolving problem?

I have a 2007 Yaris with a DTC 51 that according to other posts on this list indicate a problem in the Clock Spring.

I just replaced the clock spring with a new one and I found that there seems to have been a short in the spring on the cables with the black connector terminal on the end of the clock spring.

I've replaced everything and there's now no continuity on the cables in the the orange or the black terminals of the new clock spring.

I turned on the car and it still shows a DTC 51. I disconnected the battery and the DTC is still 51.

Have you any other advice as to how this error might be cleared?

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Originally Posted by CTScott View Post
You can make the SRS system flash the SRS light to tell you what the issue is. You jump the two terminals below on the OBD port (with the ignition off) and then turn the ignition on. The SRS light will then flash in a pattern to indicate the error. The pattern will groups of fast flashes, separated by longer off periods. If more than one DTC is logged, then the codes will be separated by even longer off periods.


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Old 06-22-2013, 09:51 PM   #8
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Originally Posted by misolith View Post
I have a 2007 Yaris with a DTC 51 that according to other posts on this list indicate a problem in the Clock Spring.

I just replaced the clock spring with a new one and I found that there seems to have been a short in the spring on the cables with the black connector terminal on the end of the clock spring.

I've replaced everything and there's now no continuity on the cables in the the orange or the black terminals of the new clock spring.

I turned on the car and it still shows a DTC 51. I disconnected the battery and the DTC is still 51.

Have you any other advice as to how this error might be cleared?
See this thread for instructions on how to clear the DTC. With the SRS, codes like this will not clear by disconnecting the battery:

http://www.yarisworld.com/forums/sho...d=1#post557473
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Old 06-22-2013, 11:08 PM   #9
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Thanks much for the note.

I've tried to test for continuity across the two circuits for the airbag SQUIB terminals. I found that there was some type of short in the old clock spring which I replaced but I can't find any short across the new replacement clock spring. I've tested continuity on the pins in the actually air bag itself and there's continuity across the pins.

Does that mean that there's a short in the airbag assembly itself?

Thanks for your help out there.

Quote:
Originally Posted by CTScott View Post
See this thread for instructions on how to clear the DTC. With the SRS, codes like this will not clear by disconnecting the battery:

http://www.yarisworld.com/forums/sho...d=1#post557473
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Old 06-22-2013, 11:53 PM   #10
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Quote:
Originally Posted by misolith View Post
Thanks much for the note.

I've tried to test for continuity across the two circuits for the airbag SQUIB terminals. I found that there was some type of short in the old clock spring which I replaced but I can't find any short across the new replacement clock spring. I've tested continuity on the pins in the actually air bag itself and there's continuity across the pins.

Does that mean that there's a short in the airbag assembly itself?

Thanks for your help out there.
Did you try clearing the DTCs with the procedure in the link above after you checked out the new clockspring?
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Old 06-23-2013, 01:44 PM   #11
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Clearing DTC after apparently resolving problem?

I tried it. Apparently I still have a problem somewhere in the circuits. I did the procedure for clearing the DTC and at the end of connecting and reconnecting the jumper the light still flashes on and off with the code 51.

One thing that happens is the P/S light starts flashing as well.

One other thing that makes me suspicious is that the Airbag light comes on immediately after removing the jumper, not the prescribed 2-4 second lag time.

I tested the new clock spring, found that it has no continuity between any of the pins on the SQUIB circuit. I plugged in the new clock spring and tested the continuity back through the clock spring down to wherever it goes in the car, no shorts.

I presume that the two pins on the orange and black terminals are the two sides of individual circuits which run up to the air bag. I test the pins on the airbag for continuity and it shows a solid connection through the airbag.

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Old 06-23-2013, 03:20 PM   #12
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Is the new one a Yaris one, or is it from some other Toyota (also is it OEM or an aftermarket one)?

If everything checks out OK through the clock spring, you should also check for continuity between the 4 airbag wires at the steering column to their other end at the SRS ECU (you have to pull the center console to get to it, just under the bottom of the AC controls).

The four wires (yellow/black, yellow, yellow-red, and yellow-green) go to the 5th, 6th, 7th and 8th positions from the top left of the SRS ECU connector.

Was the car in a crash, or did the clockspring just fail on you?
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Old 06-23-2013, 03:26 PM   #13
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The clockspring is aftermarket. I will open the console up to check into the continuity test on the ECU.

The car may have been in a crash, I recently bought it, the person doesn't know the details of the crash.

If all the equipment was replaced, what about it being in a crash would cause this error?
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Old 06-23-2013, 04:39 PM   #14
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Quote:
Originally Posted by misolith View Post
The clockspring is aftermarket. I will open the console up to check into the continuity test on the ECU.

The car may have been in a crash, I recently bought it, the person doesn't know the details of the crash.

If all the equipment was replaced, what about it being in a crash would cause this error?
The reason I asked about the crash piece is that there is a crash data recorder, where data gets written to a EEPROM within the SRS ECU. Once crash data is logged the only way to get the SRS error light to turn off is to either replace the SRS ECU or to clear the crash data from the EEPROM.

The error 51 is not related, but once you get it resolved and get the DTC cleared, if the light stays on, that is why.

I actually have the equipment to do the crash data clearing and have figured out the portions of the EEPROM that need to be cleared to do so.
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