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Home / DTC / B3A27 — Active Aerodynamic Feature Control Module A Power Mode Circuit Performance

B3A27 — Active Aerodynamic Feature Control Module A Power Mode Circuit Performance

Detailed page for trouble code B3A27.

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10,557generic
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Code

B3A27

Generic B — Body

Active Aerodynamic Feature Control Module A Power Mode Circuit Performance

Brand: Generic
Type: B — Body
Views: UK: 14 EN: 25 RU: 19
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Page language: EN

Causes

  • Blown or corroded fuse or faulty relay supplying the module
  • Low battery voltage or weak charging system
  • Open, short or high-resistance in power mode wiring or connector
  • Poor or corroded ground at the module
  • Water intrusion or connector corrosion
  • Intermittent wiring damage (pinched or chafed harness)

Symptoms

  • Active aerodynamic components fail to operate (grille shutters, spoiler not deploying)
  • Instrument cluster message or malfunction indicator related to aero system
  • Stored B3A27 and possibly related body module codes
  • Intermittent operation of aero features (works sometimes)
  • Possible reduced aerodynamic control or degraded fuel economy (if grille shutters stuck)

What to check

  • Read and record all stored codes and freeze frame data with a diagnostic scan tool
  • Verify vehicle battery state of charge and charging system voltage (11–14.5 V with engine running)
  • Inspect fuses and relays for the module power circuit; replace suspect items
  • Visually inspect module connector and harness for corrosion, bent pins, damage or water ingress
  • Backprobe module power and ground pins and measure voltage and continuity
  • Check ground resistance between module ground and chassis (should be

Signal parameters

  • Ignition-switched supply voltage to module: ~11–14.5 V when ON
  • Module ground: continuity to chassis
  • Power mode circuit voltage: close to battery voltage when enabled; near 0 V when disabled (per vehicle design)
  • Scan-tool status: module awake/online flag
  • No excessive voltage spikes on power line (

Diagnostic algorithm

  1. Connect a capable scan tool, read/record all codes and freeze frame, then clear codes and attempt to re-run the fault cycle to confirm repeatability.
  2. Verify battery voltage and charging system health. Recharge or replace battery if below specification before continuing.
  3. Inspect and test related fuses and relays. Replace any blown fuse and swap/bench-test suspect relays.
  4. Visually inspect the module and wiring harness for damage, corrosion or water intrusion. Repair or replace damaged connectors/wiring.
  5. Backprobe the module power-mode supply pin with ignition ON and command the aerodynamic device from the scan tool while monitoring voltage. Compare readings to expected values.
  6. Check module ground(s) for resistance to chassis; repair poor grounds and re-test.
  7. If intermittent, perform wiggle tests on harnesses while monitoring live data. Use a scope to check for noise or spikes if available.
  8. If wiring, connectors and supply/grounds are good, consider reflashing module software if updates exist. Re-test after update.
  9. If all external circuits check good and module does not respond correctly, replace the Active Aerodynamic Feature Control Module A and re-test system functionality and codes.
  10. After repairs, clear codes and verify problem does not return under normal operation.

Likely causes

  • Ignition-switched 12V supply fuse (fuse blown or loose)
  • Faulty power/logic relay in the feed circuit
  • Damaged power mode circuit wires or poor terminal contact at module connector
  • High resistance or open ground at module mounting point
  • Module internal electronics degraded due to moisture or over-voltage

Fault status

⚠️ Status
Active Aerodynamic Feature Control Module A — Power Mode Circuit Performance. Power/voltage or circuit performance is outside expected range; module may be unable to drive or correctly report status of active aerodynamic devices.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours

Similar codes

B3A24 B3A25 B3A26 B3A28 B3A2A
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