Airbag Troubleshooting: My Attempt

So today I attempted some troubleshooting on my 1995 Tacoma that I recently inherited. My great uncle “fixed” the two dash lights with pieces of black tape. For me, knowing that they’re there is driving me nuts! So I attempted some problem isolation today. I would love feedback and if I’m making any bad assumptions here about what I believe the problem is, or if I did anything dead wrong!

I have two airbag codes: #12 and #31.

1) Code 12 is a battery short on D circuit to the wheel airbag squib.
2) code 31 is an error with the airbag control module.

I suspected that the problem is the module, but needed to confirm.

Here is how I diagnosed what I believe to be the problem, and maybe this helps someone in the future!

STEPS:
1) Disconnect the negative terminal on the battery, and wait at least 3-5 minutes MINIMUM. I waited 15 minutes and set up while waiting.

2) I placed a Jumper wire as shown below in the engine diagnostic port. This will cause the engine light to flash in a pattern that will tell you what your code #s are. Mine flash 12 and 31.


3) Next, I removed the Airbag from the wheel. This requires loosening qty. 2 30 torx screws from the side of the steering wheel. The squib connector was a little difficult to figure out, but I eventually got it.
SET THE AIRBAG FACE UP WHEN YOU SET IT DOWN.


4) Next, find the Airbag Control Module and disconnect the connector. This is located under the radio. To remove the panel, there are two plastic clips that need to be pryed out.


5) Now, time to troubleshoot. The FSM states to start with the spiral cable isolation.


With the module connector out, and the airbag removed, you have isolated the clock spring and wiring harness for a short check. I took a meter on one of the squib wires and connected the other to body ground.

With this setup, now connect the battery and turn the key to ON or ACC. If the clock spring were to be the source of the short, I would expect to now see the battery voltage on one of the lines. I did not.

6) Next, I shorted the squib wires together to simulate the squib being there, in case the airbag itself is bad. Not sure why the FSM has this listed as a source of battery voltage, but I did it anyway. With the key ON, the codes still persisted.


7) Next, I checked out the airbag module. To do this, keep the same meter reading locations, but now plug in the airbag module cable. In my case, when the key was turned to ON, the airbag light came on, flashed the same codes, AND I saw a 14 VDC reading on one of the squib lines.

This leads me to believe that the module is bad. Connecting and disconnecting the cable sensor tracked with me seeing and losing battery voltage on the squib lines. I’m going to try to find a replacement module for cheap to swap.

What did I do wrong here? Has anyone else seen this problem before? If anyone can help me locate a replacement module that would be great!

 

Awesome documentation!

my AB lite fickle…..
Dim
Not on(correct)
Full illumination
Typically corrects itself after 20mins

figured it’s the module too

as far as the Morse code error codes
I discovered that multiple codes pop
But once the bad component replaced, all go away after reset