DTC B100C:12 [Advanced Keyless Entry And Push Button Start System]: Notes

WARNING: This page is about a different car, the 2010 Mazda 3. However, it is still accessible from the selected car via links, so may be relevant.

WARNING:

If this DTC is detected, the system will enter the fail-safe function to ensure safety. If the vehicle left as it is for a specified time limit or more, or the ignition is operated a specified number of times or more while the fail-safe function is operating, the ignition will remain stuck in off and it is possible that the engine cannot be started. Therefore, perform the malfunction diagnosis while the engine can be started. In addition, after having performed the malfunction diagnosis, verify that this DTC is not detected with the steering wheel locked. If the DTC is not detected, the system returns to normal from the fail-safe function.

NOTE:

When the system enters the fail-safe function, the keyless warning light and the push button start indicator light illuminate as follows:
- When the clutch pedal (MTX) or the brake pedal (ATX) is depressed while the ignition is switched off, both lights illuminate (red).
- When the ignition is switched to ACC or ON, both lights illuminate (red) constantly.
  
  Fig 1: Identifying Keyless Waring Light And Push Button Start Indicator Light
  Courtesy of MAZDA MOTORS CORP.

DTC B100C:12 (ADVANCED KEYLESS ENTRY AND PUSH BUTTON START SYSTEM) DETECTION CONDITION AND POSSIBLE CAUSE

DESCRIPTION	Short to power supply in steering lock unit power supply circuit
DETECTION CONDITION	Steering lock unit power supply moitor is on for 3 s when the steering lock unit power supply transistor is not active.
POSSIBLE CAUSE	Steering lock unit connector or terminals malfunction Keyless control module connector or terminals malfunction Short to power supply in wiring harness between the following terminals: Steering lock unit terminal B-Keyless control module terminal 1C Steering lock unit malfunction Keyless control module malfunction
Courtesy of MAZDA MOTORS CORP.