Toyota Nation Forum banner

DIY: Airbag Crash Data Reset

16K views 7 replies 3 participants last post by  Bitter 
#1 · (Edited)
When a vehicle is rebuilt after a collision involving airbag deployment, the airbag computer must be replaced. Here’s a video on how to clear the crash data from the airbag computer and reprogram it with clean virgin data.



The airbag computer controls the supplemental restraint system in your vehicle, including the airbag sensors, inflators and seat belt pretensioners. It also acts as a black box when you get into a major collision that involved airbag deployment.
Let’s say you get into a collision with your beige Corolla.


And your airbags deploy:



Well if you decide to rebuild the vehicle and replace the airbags:



You need to replace the SRS computer, since it has a hard code inside that can’t be erased and you’ll be stuck with an airbag light on:




You won’t even be able to access the SRS computer using Toyota’s techstream software either:



The airbag computer is located underneath the dashboard. The bottom half needs to be removed to access it.




Disconnect battery before working on SRS system:


Airbag computer removed:



Open up the computer:




We’re looking for this 8 pin SMD EEPROM chip here that stores the crash data, it says L56R on it:



Solder some 32 gauge hookup wire to connect it to the serial port EEPROM reader:




I built a little EEPROM reader using some resistors and diodes:

Here’s the setup, with the airbag computer EEPROM going to the reader, and then the reader going to the serial port directly on a legacy Pentium 4 computer. You can also purchase USB EEPROM readers:



Then I used PonyProg software which is a serial device programmer to read from the EEPROM chip:


Here’s what the crash data looks like:


From a clean, uncrashed Corolla, I dumped the information from its SRS computer and it looks like this:



Comparing the two, you can see a lot of data values have changed.



So now I’m going to replace all the values from the crashed chip with those from the virgin chip and rewrite it to the computer to clear the hard code. Then I’ll replace it into the vehicle:



The SRS light should go out within 6 seconds if everything is functioning normally. I also double checked it with Toyota’s techstream software and there aren’t any codes or faults found.

It works!

 
See less See more
1 23
#2 · (Edited)
LOVE IT!!!
I should build a little circuit board that does that for you.
What were your resistors and diodes??
I make tons of circuit boards each month for all my projects...
These just came in this week.
Could easily use my hot air work station to pull that chip, reprogram them and then put the right back on the board..


 
#3 ·
LOVE IT!!!
I should build a little circuit board that does that for you.
What were your resistors and diodes??
I make tons of circuit boards each month for all my projects...
These just came in this week.
Could easily use my hot air work station to pull that chip, reprogram them and then put the right back on the board..
Thanks.
If you look through the photos above I posted the schematic with the circuit diagram, I used 4.7Kohm resistors and 5V zener diodes. My brother soldered them up on a nice little board with a DIP socket on it (see the pics).

I've played around with a lot of EEPROMs in cars, from the odometer to immobilizer and now SRS computer. Check out my YouTube channel for more info on those.
 
#4 ·
Could you make a 'socket' that could be placed on top of the chip that would latch to the sides of it and make contact with the leads so no soldering is needed? You could have a pigtail off the 'socket' to a circuit board with the serial port. I imagine that many other Toyota models use the same chip on their airbag computers, seems like it could be a useful device! Heck, it would would on any other chip with the same layout.
 
#5 ·
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top