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Home / DTC / B2656 — Supplemental Restraint System (SRS) Control Module Internal Fault

B2656 — Supplemental Restraint System (SRS) Control Module Internal Fault

Detailed page for trouble code B2656.

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Code

B2656

LAND ROVER B — Body

Supplemental Restraint System (SRS) Control Module Internal Fault

Brand: LAND ROVER
Type: B — Body
Views: UK: 5 EN: 11 RU: 6
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Page language: EN

Causes

  • Internal electronics or memory failure inside the SRS control module
  • Corrosion or water ingress into the module or connector
  • Power supply (fuse, ignition feed) or ground fault to the module
  • Damaged or shorted airbag/squib wiring causing fault conditions
  • Corrupted software/calibration or failed reflash
  • Stored crash data not cleared after an event

Symptoms

  • SRS/Airbag warning light illuminated (constant)
  • Possible loss of airbag deployment capability or pretensioner operation
  • Intermittent or permanent communication errors with SRS module on diagnostic tool
  • Other modules reporting CAN-bus related errors or reduced functionality
  • Inability to clear code using generic scan tool; code returns immediately

What to check

  • Record all stored SRS codes and freeze-frame data with an OEM-capable scan tool before clearing.
  • Inspect SRS module area for physical damage, corrosion, signs of water ingress or impact.
  • Verify battery state and measure battery/restored voltage (>= 12.0 V recommended during test/flash).
  • Check SRS fuses and fuseholders; verify ignition feed (12 V) and ground to module connector.
  • Check connector(s) for bent pins, corrosion, loose terminals and secure mating.
  • Verify CAN bus communication to the module; check for Uxxxx communication codes.

Signal parameters

  • Module supply voltage: ignition on ~11–14.5 V (verify at module connector power pin using OEM pinout).
  • Ground continuity: low resistance (
  • CAN bus: CAN_H and CAN_L should show correct differential signaling and idling voltages (~2.5 V nominal; differential with communication activity).
  • Squib circuits: typical airbag squib resistance ranges are low (usually ~1–5 Ω) — check exact spec in manual and only measure per safety procedure.
  • SRS lamp status: lamp should extinguish after successful self-test; if lamp stays on, module reports a fault.
  • Diagnostic responses: module should provide full SID/PID and DTC information via OEM diagnostic tool.

Diagnostic algorithm

  1. Safety first: follow vehicle manufacturer SRS safety procedures (battery disconnect times, disable airbags, wear PPE). Refer to the workshop manual before touching SRS circuits.
  2. Connect an OEM-capable diagnostic tool and read all stored DTCs and freeze frame. Save or note codes and events.
  3. If other modules show CAN or communication faults, diagnose CAN network issues first (shorts, open terminations, power/ground faults).
  4. Visually inspect the SRS module and harness for signs of water, impact damage, or previous repairs. Repair damaged wiring or connectors as needed.
  5. Verify battery voltage at the module with ignition on. Inspect and test SRS fuses and relays for correct operation.
  6. Backprobe module connector to verify presence of proper power and grounds at the specified pins. Repair any poor power/ground connections.
  7. Check CAN bus activity at the module connector with an oscilloscope or CAN tester; resolve any bus errors or wiring faults.
  8. Check for stored crash/impact data. If crash data is present, follow manufacturer policy — many modules containing crash data must be replaced, not cleared.
  9. If power/ground/communications are correct and wiring is good, attempt an OEM-authorized software reflash or recalibration of the SRS module per service procedure.
  10. If reflash fails or faults persist after confirming vehicle wiring and software are correct, replace the SRS control module with a dealer/OEM unit and program/configure it as required by the manufacturer.
  11. After repair or replacement, clear codes and perform manufacturer-specified SRS system tests and verification. Confirm SRS lamp extinguishes and no DTCs are present.

Likely causes

  • Module experienced a voltage spike or reverse polarity that damaged internal circuitry
  • Connector pins corroded or bent allowing intermittent contact
  • Previous repair or crash repair left module with crash-data set or incorrect calibration
  • Water ingress behind dashboard contacting the module
  • Battery was disconnected or low during a previous update leaving firmware corrupted
  • Short to ground or open in the module power or ground circuit

Fault status

⚠️ Status
SRS control module reports internal malfunction (hardware, memory or software). Module may be non-serviceable and require replacement and programming. Follow OEM diagnostics and safety procedures.
🔴 Repair difficulty: Hard
⏱️ Diagnostic time: 2.0-4.0 hours

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B2655 B2657 B2640 B2621 U0073 U0100
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