B3A30

Code

Generic B — Body

Active Aerodynamic Feature Control Module D Power Mode Circuit High Voltage

Brand: Generic

Type: B — Body

Views: UK: 21 EN: 47 RU: 24

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Short or unintended connection from power (battery/alternator) to the module power/mode circuit
Failed Active Aerodynamic Feature Control Module D (internal short or failed regulator/overvoltage detection)
Damaged, frayed, or chafed wiring harness causing a short to battery voltage
Corroded, loose, or damaged connector pins resulting in intermittent high readings
Faulty relay or fused power input feeding the module
Overcharging charging system (alternator/regulator) causing system voltage above safe limits

Symptoms

Instrument cluster warning lamp or message about aerodynamic system fault
Active aerodynamic devices stuck in one position, fail to move, or operate unpredictably
Stored B3A30 (and possibly related) DTC(s) in vehicle control modules
Possible limp or degraded mode for aerodynamic system
Visible corrosion or heat damage at module connector in some cases

What to check

Read and record B3A30 freeze frame and any related DTCs from all modules
Visually inspect connectors, pins and wiring for damage, corrosion, or water ingress at the module and harness routing
Check battery voltage at rest and while engine is running to evaluate charging system
Measure voltage at the module power/mode pin with respect to ground (key ON, engine off and running) and compare to expected ranges
Disconnect the module connector and check for battery voltage present on the power/mode circuit (to locate short)
Check fuses and power/ground feed relays associated with the aerodynamic control module

Signal parameters

Nominal vehicle battery voltage (key ON, engine off): ~12.0–12.8 V
Charging voltage (engine running): normally ~13.5–14.8 V; sustained voltages above ~15.5–16 V are abnormal
Module power input: should track battery/ignition feed; unexpected voltages above normal battery/charging range indicate high-voltage condition
Logic/control pins (if present) typically operate in low-voltage domain (e.g., 0–5 V); any reading significantly above that range is abnormal

Diagnostic algorithm

Retrieve B3A30 and any related codes; note freeze-frame data (key on/off, engine rpm, battery voltage).
Visually inspect module, connector, and harness for melted insulation, corrosion, damaged pins, or signs of water entry. Repair obvious damage before further testing.
Measure battery voltage (key off, key on, engine running) to rule out charging system overvoltage. If charging >15.5 V, diagnose alternator/regulator first.
With ignition ON (engine off), backprobe the module power/mode terminal and measure voltage to ground. Compare to battery/ignition voltage. If voltage is higher than battery/charging voltage, suspect wiring fault or module internal fault.
Disconnect the module connector. Re-measure voltage at the harness power/mode terminal with connector disconnected. If the high voltage remains with the module disconnected, the short is upstream; if voltage drops to normal, suspect module internal fault.
Inspect upstream circuits (relays, fused feeds, other modules) for unintended connections to a higher-voltage source. Use a fused jumper or test lamp to trace shorts if necessary.
Check continuity from the module power/mode pin to battery positive and to associated fuses/relays. Check for shorts to other circuits or to chassis ground.
If wiring and power feeds are verified good and no external overvoltage source is found, replace the Active Aerodynamic Feature Control Module D and clear codes. Re-test operation and confirm no reoccurrence.
After repair, confirm charging system outputs are within specification and perform a road test to validate proper aerodynamic device operation. Monitor for recurrence and re-scan for codes.

Likely causes

Wiring short to battery on the module power/mode input
Internal failure in the Active Aerodynamic Feature Control Module D
Corroded or pushed-back terminal in connector allowing stray voltage
Faulty power relay or fuse circuit tied to the module supply
Vehicle charging system producing high voltage

Fault status

⚠️ Status

High voltage detected on the Active Aerodynamic Feature Control Module D power/mode circuit. Aerodynamic control functions may be disabled until the condition is corrected.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours