Mazda3 FORScan Tweaks (BM/BN, 2014–2018)

This page covers what is specific to the 3rd-generation Mazda3 (BM 2014–2016, BN facelift 2017–2018), the Mazda3 years that run Gen 6 MZD Connect and share the SkyActiv body-control architecture with the MX-5 and CX-5. The 2019+ Mazda3 (BP, 4th gen) is a different platform and is not covered.

FORScan writes to body control modules over OBD-II; it does not touch the CMU. For head-unit changes (apps, themes, disclaimer removal) see tweaks. For the shared FORScan workflow (extended license, adapter choice, and AS-Built backup), read these first:

FORScan overview: workflow and prerequisites
Adapter buying guide: MS-CAN adapter selection
AS-Built backup and restore: back up before any write
Complete mod list: every documented byte change

Back up AS-Built before changing anything. All changes are reversible by restoring original values.

Module map

The module addresses are identical to the MX-5 and CX-5. Byte layouts are largely the same; baseline values differ by trim and model year.

Module	Address	Controls
RBCM	0x7B7	Door locks, lighting, Find My Car, trunk
FBCM	0x726	DRL, headlights, wipers, fog, ESS
SSU	0x731	i-Stop, keyless entry
IC	0x720	Gauge cluster, ADAS display, camera
PCM	0x7E0	Powertrain

BM vs. BN

Factor	BM (2014–2016)	BN (2017–2018)
RBCM baseline	Earlier calibration	Updated defaults
FBCM	Same structure	LED headlight options more common
IC	Older cluster format	Updated cluster, more options
ADAS hardware	Limited (base models)	More common on higher trims
Sedan vs. hatch	Same modules	Same modules

Most documented Mazda3 changes work on both BM and BN unchanged. The difference is mainly which features are factory-enabled by default: on a BN you may be flipping a bit that a BM already has on, or vice versa.

Mazda3-specific changes

These are the changes where the Mazda3 baseline or hardware differs from the shared MX-5/CX-5 procedure. Locks, ESS, and Find My Car use the same RBCM/FBCM bytes across the platform; see the complete mod list for those.

Auto door lock/unlock

Identical bytes to the MX-5 and CX-5.

RBCM 7B7-01-01:

B1 b7 = 1 (master enable)
B4 b6 = 1 (lock when ignition ON)
B4 b3 = 1 (allow lock with doors open)

RBCM 7B7-01-02:

B4 b5 = 1 (CMU menu visibility)
B4 b3 = 0 (display setting)

Reset the CMU Lock settings page after writing for the options to appear.

DRL configuration

The Mazda3 has several DRL options depending on headlight type, more than the MX-5, because LED headlights were common on higher BN trims.

FBCM 726-01-01 B0: b2 = 0 (DRL enable, inverted logic)

FBCM 726-50-01 DRL source:

01xx = Parking lights
02xx = Parking lights + low beams
08xx = Turn-signal lamps (LED signature DRL)

On 2017–2018 Touring and Grand Touring with factory LED headlights, the LED DRL strip may be controlled differently than halogen DRL. Verify current behavior before modifying.

i-Stop default OFF

SSU 731-01-01 B1: b4 = 0

Defaults i-Stop to OFF at startup; the button still toggles it manually.

Auto-fold mirrors

Available on Grand Touring and above, where power-fold hardware is present:

Confirm a power-fold button exists on the driver’s door switch pack
If present, RBCM configuration enables auto-fold on lock
If no power-fold hardware, the change has no effect

One-touch turn signals

Some trims have one-touch (3-blink) signals from the factory. The enable bits in RBCM 7B7-01-xx vary by model year and region; check current community documentation rather than copying blindly.

ADAS by trim

The Mazda3 shipped with more ADAS hardware than the ND MX-5, so more IC display options can be safely enabled, but only where the trim actually has the sensors.

Feature	Trims	Hardware
BSM	Touring+, Grand Touring	Rear radar
SCBS	Grand Touring	Forward camera
LDWS	Grand Touring	Forward camera
MRCC	Grand Touring (Tech package)	Front radar
HBC	Grand Touring	Forward camera

If your trim lacks the hardware, enabling the display option does nothing.

Notes

Sedan vs. hatch: body style does not affect module addresses or byte layouts.
2.0L vs. 2.5L: body-control configs are identical; PCM differs but is irrelevant for locks/DRL/i-Stop/ESS.
Region: EU models mandate DRL, so the FBCM baseline already reflects it; “enabling” DRL on an EU car may be the factory state. JDM feature sets differ.
Firmware version affects some module behavior; see Mazda3 firmware compatibility.

Community resources

Mazda3Revolution ASBuilt thread: the deepest Mazda3 FORScan reference (300+ pages); most configs there apply directly to BM/BN
Supported vehicles: cross-vehicle feature support