In the October 2016 issue, we touched upon Mazda’s AAS system. We compared it to other systems, seeing differences and similarities. One of the things we learned is that failures in other systems can affect the AAS, putting it into fail safe, in this case, the Supplemental Restraint System, or SRS.
You may remember that the vehicle we were looking at didn’t allow us to reset the system due to “airbag issues.” So first, we need to diagnose the airbag to correct this issue and be able to reset the AAS system.
We start by connecting a scan tool and pulling codes in both global and OE protocols. Here are the DTCs that showed up: B101, B1048, B1925, B1933, B1935, B1938, B104C, B104F, B1050, B2017, B1055, B1996, B1997, B1998, B1999 as well as some other body codes. The list was just too long; we’d never be able to fix them all!
Okay, breathe… let’s look up what these codes mean and see if there’s any connection between them. Turns out all of these codes pointed toward the SRS module. When you see a list like this, it’s tempting to assume the module is toast and needs to be replaced. But before we replace any module, we need to check for power and ground. This one’s completely dead.
So now we start removing panels and rugs, tracing the wiring, checking fuses and connections. Turns out the car had been through a body shop after being T-boned on the passenger’s side. So out comes the seat, more panels, and — voila! — there’s the wiring harness, all butchered up.
The impact bent the D pillar and cut the wires, which had to be spliced back together, one wire at a time. In addition, there were signs of water intrusion. Turns out the passenger window shattered on impact and, while the vehicle sat in the parking lot waiting for repairs, it very likely got rained on.
We performed the appropriate repairs, reinstalled the computer, and most of the codes cleared. But now the crash sensor kept popping up. We ordered the side crash sensor and installed it. The code cleared. Perfect; time to drive the car.
We charged the battery and on the road test we go. Everything seems to be operating well until the vehicle warms up and two codes come back: B1013 and B2477. B1013 is passenger seat weight calibration; B2477 is SRS module configuration. Once again, the codes are related to one another.
B2477 indicates the computer for the SRS isn’t configured. But remember, these newer model cars have their own form of CAN-BUS communication system, so the computer may be seeing something it doesn’t like. So we start with code B1013. That means we need to perform the procedure to recalibrate the passenger side airbag and module; here’s how:
Initial Prechecks
- Inspect the passenger side front seat.
- Turn the ignition switch to the lock position.
- Disconnect the negative battery cable for at least one minute.
- Remove the passenger-side front seat and visually inspect for:
- Seat under-bracket deformation
- Seat frame deformation
- Seat weight sensor deformation
- Foreign objects stuck in seat
Are any of the parts deformed or are any foreign objects stuck in the seat? Repair or replace as necessary.
- Inspect the floor.
- Visually inspect the installation parts of the passenger side front seat for:
- Floor is deformed
- Installation hole of the passenger side front seat is positioned improperly.
If everything else looks okay, you’re ready to perform the module calibration procedure.
Module Calibration
To calibrate the module, you’ll need:
- One, 4.5kg (10 pound) weight
- Two, 20.0kg (44 pound) weights
Once you have those weights on hand, you’re ready to begin the procedure:
- Connect the M-MDS to the DLC-2 connector.
- After you’ve identified the vehicle, select the appropriate items from the initialization screen of the M-MDS, depending on the system you’re using: When Using the IDS (Laptop PC)
- Select “Body.”
- Select “Restraints.” When Using the PDS (Pocket PC)
- Select “All Tests and Calibrations.”
- Select “Passenger Seat Weight Sensor Re-Zero.”
- Perform the calibration, following the procedures on the M-MDS screen.
IMPORTANT: The scan tool doesn’t hold the procedure to calibrate the SRS module, and it doesn’t appear in Mitchell, ALLDATA, or MOTOR manuals.
This is where you’ll need the weights to calibrate the seat, based on the item or person sitting there.
The 10-pound weight calibrates the passenger seat sensor for a bookbag, groceries, or any article that the driver might lay there. Recognizing this weight threshold, the computer will learn that it shouldn’t deploy the passenger side airbag in the event of a collision. Follow the procedure from the Mazda web site for the calibration.
Make sure you pay close attention to the procedure: Certain model vehicles have one sensor while others have four, receiving information from multiple locations. Sport models, or those vehicles with lumbar support, may have up to six sensors. Calibrations vary depending on the model you’re working on.
The next threshold is 20kg — about 45 lbs. This is to calibrate the system for the weight of a child in a child safety seat. This step is critical because there have been a number of cases of neck injury or even death reported that were caused by the deployment of the passenger airbag.
The liability is high if you are involved in such repairs, so be sure to follow protocol and document everything you do or change, including parts, modules, wires, and so on.
The third weight is 40kg (about 88 pounds). It calibrates the airbag system for the weight of an adolescent or small person. This is why you needed two of the 20kg weights. Follow the instructions from the Mazda web site; you should make it through the calibration without any problem.
Once we completed the calibration, the two codes cleared. From there, it was just a matter of replacing the panels and trim to put the car back in deliverable condition.
