B3A22

Code

Generic B — Body

Active Aerodynamic Feature Control Module C

Brand: Generic

Type: B — Body

Views: UK: 26 EN: 39 RU: 29

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Loss of power or ground to Active Aerodynamic Feature Control Module C
Corroded, loose, or damaged connector or wiring to the module
CAN bus or LIN bus communication fault between module and vehicle network
Internal module failure (hardware or firmware)
Related actuator, sensor, or motor failure causing module to report an error
Blown fuse or relay feeding the module

Symptoms

Malfunction message or warning lamp related to active aero features
Active grille shutters, spoiler, or diffuser not operating or stuck in one position
Reduced aerodynamic control leading to decreased economy or performance
Intermittent operation of aero components
Related systems show communication errors or reduced function

What to check

Read DTCs and freeze frame data from all modules; note any network U-codes
Attempt to clear the code and see if it returns or is intermittent
Visual inspection of module connectors, pins, and wiring for damage or corrosion
Check fuses and relays that supply the active aerodynamic module
Verify battery voltage at the module connector with ignition on
Check ground continuity from module ground to chassis/negative battery

Signal parameters

Module supply voltage: ~11–15 V with ignition on (nominal ~12–14.5 V)
Ground continuity:
CAN bus idle (recessive) common-mode ~2.5 V per line; differential ~0 V; active (dominant) differential typically ~1–3 V
LIN bus idle ~battery voltage through pull-up; signals are typically 0–12 V pulses
Actuator drive outputs: pulses or PWM as specified by manufacturer (check with scope)

Diagnostic algorithm

Record all DTCs and freeze-frame data from the vehicle. Note timestamps and related U-codes.
Check simple items first: battery state, related fuses/relays, and visually inspect the module connector for damage/corrosion.
Attempt to communicate with the module using a bi-directional scan tool. If the module does not respond, check supply and ground at the module connector.
Verify vehicle network health: check CAN/LIN bus for activity and correct voltages with a scope or network tester. Repair any open/shorts or shorts-to-power/ground.
If supply, ground, and network are good, inspect wiring between module and actuators/sensors for continuity and short circuits.
Perform actuator function tests via scan tool (if available) to exercise shutters/spoiler/motors. Verify expected responses and measure drive signals.
If module firmware is outdated or a recent replacement occurred, check for software updates or programming requirements and reflash if recommended.
If fault persists after verifying power, ground, network and actuators, consider module replacement following manufacturer procedures. Reprogram/configure module if required.
After repairs, clear codes and perform a road test or operation cycle to confirm the fault does not return and aero components operate correctly.

Likely causes

Poor battery voltage or intermittent supply to the module
Damaged wiring harness at a common stress/repair point (pinch, chafing)
Water intrusion/corrosion at module connector
Module lost on the vehicle network (no CAN/LIN ID)
Actuator stuck or shorted causing module fault reporting

Fault status

⚠️ Status

Active Aerodynamic Feature Control Module C reports a fault or communication error. The module may be experiencing power, ground, wiring, network, actuator, or internal hardware/software issues affecting operation of active aerodynamic components.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.5 - 3.0 hours

Repair manuals