Looking at seats... - Page 14 - Toyota Yaris Forums

CTScott · 08-20-2009, 02:58 PM

OK. With ignition power off, try reading resistance between the center wire and either of the outside wires. That will verify if you're actually making a good connection to the wire. You should see 48K ohms between the center and either outside wire.

MGargano · 08-20-2009, 03:07 PM

Ok. Should I keep the sensor clamped for this exercise? And I assume I'm changing the setting on the multimeter from VDC to ohms?

CTScott · 08-20-2009, 03:12 PM

Correct on VDC to ohms. Clamping is fine - It won't have any effect on the readings.

MGargano · 08-20-2009, 03:22 PM

Which setting am I putting the multimeter to?

I got a reading each time (center to left and center to right) with the black lead on center and the red on either outside wire but I have a feeling I have the meter on the wrong setting.

CTScott · 08-20-2009, 03:26 PM

Put the meter on 200K (always go to the next highest above what you are trying to see).

MGargano · 08-20-2009, 03:45 PM

Ok, with the meter on 200k, black lead in the center, red on either outside wire, I got 4.4 both times. I tried a few times and the numbers kept bouncing around some, but the most consistent (when I held my hands steady) was 4.4.

CTScott · 08-20-2009, 04:07 PM

OK. So right now your SRS light is off, air bag off is lit, and passenger seat belt is lit?

Try disconnecting the battery for 2 minutes, reconnecting and then measuring the voltage on the center pin to ground. for a really solid ground you might want to pop the passenger kick panel and touch the black lead to the ground bolt there.

MGargano · 08-20-2009, 04:13 PM

Quote:

Originally Posted by CTScott

OK. So right now your SRS light is off, air bag off is lit, and passenger seat belt is lit?

No, sir. All three lights, including the SRS, are still lit.

CTScott · 08-20-2009, 04:32 PM

Here's what I've found with the oscilloscope - Every 100ms the sensors transmit a packet of data. The beginning of the packet is always the same and the latter part varies based on pressure on the sensor.

Here are two sequential data packets from the front right sensor:
FR - Weight - Period.JPG

Here is one packet with no weight on the sensor:
FR - No Weight.JPG

Here is one packet with enough weight on the sensor for the airbag light to be lit:
FR - Weight.JPG

Based on this I can easily build a module to simulate the sensors (and to switch between an empty and occupied seat).

MGargano · 08-20-2009, 05:21 PM

Quote:

Originally Posted by CTScott

Try disconnecting the battery for 2 minutes, reconnecting and then measuring the voltage on the center pin to ground. for a really solid ground you might want to pop the passenger kick panel and touch the black lead to the ground bolt there.

I just tried this and registered nothing with the meter set to VDC. When I moved it to 200k ohms, it registered 6.0 between the center pin/wire and ground.

CTScott · 08-20-2009, 05:51 PM

Quote:

Originally Posted by MGargano

I just tried this and registered nothing with the meter set to VDC. When I moved it to 200k ohms, it registered 6.0 between the center pin/wire and ground.

It really looks like your OC ECU is not responding. Take a close look at all of the wiring to and from it. Look for any sign of a damaged wire.

MGargano · 08-20-2009, 06:57 PM

Quote:

Originally Posted by CTScott

It really looks like your OC ECU is not responding. Take a close look at all of the wiring to and from it. Look for any sign of a damaged wire.

I don't see any signs of damaged wiring or anything else out of the ordinary. I can't think of anything I might have done to damage it (dropping, etc) so I hate to think there's a problem with it. Should I start looking for a replacement?

CTScott · 08-20-2009, 04:18 PM

With the SRS, are you still seeing the DTC 32?

MGargano · 08-20-2009, 04:23 PM

I just checked it. I now have 32, 55, & 56 again.

CTScott · 08-20-2009, 04:30 PM

You might want to check your resistors. I had trouble with mine not making great contact. I ended up shoving mine in through the wire side so they would fit tighter.

MGargano · 08-20-2009, 04:31 PM

Quote:

Originally Posted by CTScott

You might want to check your resistors. I had trouble with mine not making great contact. I ended up shoving mine in through the wire side so they would fit tighter.

Ok, I'll try that. Then do the dreaded reset of the SRS ECU again?

CTScott · 08-20-2009, 04:35 PM

Quote:

Originally Posted by MGargano

Ok, I'll try that. Then do the dreaded reset of the SRS ECU again?

Oh yeah. I've gotten mighty good at doing it.

MGargano · 08-20-2009, 04:36 PM

Quote:

Originally Posted by CTScott

Oh yeah. I've gotten mighty good at doing it.

Haha! Feel like taking a road trip to Jersey and doing it for me?

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08-20-2009, 02:58 PM	#1
CTScott ULTIMATE View User's Garage Drives: 09 5dr LB, 2x 08 3dr LB Join Date: Oct 2008 Location: USA, CT Posts: 13,460	OK. With ignition power off, try reading resistance between the center wire and either of the outside wires. That will verify if you're actually making a good connection to the wire. You should see 48K ohms between the center and either outside wire.

08-20-2009, 03:07 PM	#2
MGargano Drives: 2009 Yaris Hatchback Join Date: Feb 2009 Location: NJ Posts: 792	Ok. Should I keep the sensor clamped for this exercise? And I assume I'm changing the setting on the multimeter from VDC to ohms?

08-20-2009, 03:12 PM	#3
CTScott ULTIMATE View User's Garage Drives: 09 5dr LB, 2x 08 3dr LB Join Date: Oct 2008 Location: USA, CT Posts: 13,460	Correct on VDC to ohms. Clamping is fine - It won't have any effect on the readings.

08-20-2009, 03:22 PM	#4
MGargano Drives: 2009 Yaris Hatchback Join Date: Feb 2009 Location: NJ Posts: 792	Which setting am I putting the multimeter to? I got a reading each time (center to left and center to right) with the black lead on center and the red on either outside wire but I have a feeling I have the meter on the wrong setting.

08-20-2009, 03:26 PM	#5
CTScott ULTIMATE View User's Garage Drives: 09 5dr LB, 2x 08 3dr LB Join Date: Oct 2008 Location: USA, CT Posts: 13,460	Put the meter on 200K (always go to the next highest above what you are trying to see).

08-20-2009, 03:45 PM	#6
MGargano Drives: 2009 Yaris Hatchback Join Date: Feb 2009 Location: NJ Posts: 792	Ok, with the meter on 200k, black lead in the center, red on either outside wire, I got 4.4 both times. I tried a few times and the numbers kept bouncing around some, but the most consistent (when I held my hands steady) was 4.4.

08-20-2009, 04:07 PM	#7
CTScott ULTIMATE View User's Garage Drives: 09 5dr LB, 2x 08 3dr LB Join Date: Oct 2008 Location: USA, CT Posts: 13,460	OK. So right now your SRS light is off, air bag off is lit, and passenger seat belt is lit? Try disconnecting the battery for 2 minutes, reconnecting and then measuring the voltage on the center pin to ground. for a really solid ground you might want to pop the passenger kick panel and touch the black lead to the ground bolt there.

08-20-2009, 04:32 PM	#9
CTScott ULTIMATE View User's Garage Drives: 09 5dr LB, 2x 08 3dr LB Join Date: Oct 2008 Location: USA, CT Posts: 13,460	Here's what I've found with the oscilloscope - Every 100ms the sensors transmit a packet of data. The beginning of the packet is always the same and the latter part varies based on pressure on the sensor. Here are two sequential data packets from the front right sensor: FR - Weight - Period.JPG Here is one packet with no weight on the sensor: FR - No Weight.JPG Here is one packet with enough weight on the sensor for the airbag light to be lit: FR - Weight.JPG Based on this I can easily build a module to simulate the sensors (and to switch between an empty and occupied seat).

08-20-2009, 04:18 PM	#13
CTScott ULTIMATE View User's Garage Drives: 09 5dr LB, 2x 08 3dr LB Join Date: Oct 2008 Location: USA, CT Posts: 13,460	With the SRS, are you still seeing the DTC 32?

08-20-2009, 04:23 PM	#14
MGargano Drives: 2009 Yaris Hatchback Join Date: Feb 2009 Location: NJ Posts: 792	I just checked it. I now have 32, 55, & 56 again.

08-20-2009, 04:30 PM	#15
CTScott ULTIMATE View User's Garage Drives: 09 5dr LB, 2x 08 3dr LB Join Date: Oct 2008 Location: USA, CT Posts: 13,460	You might want to check your resistors. I had trouble with mine not making great contact. I ended up shoving mine in through the wire side so they would fit tighter.