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Home / DTC / B1407 — Trailer control module

B1407 — Trailer control module

Detailed page for trouble code B1407.

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59brands
10,557generic
22,461specific
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Code

B1407

LAND ROVER B — Body

Trailer control module

Brand: LAND ROVER
Type: B — Body
Views: UK: 6 EN: 11 RU: 10
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Page language: EN

Causes

  • Blown fuse or faulty relay supplying the trailer control module
  • Damaged, corroded or loose connector at the trailer module or hitch plug
  • Open, shorted or chafed wiring in trailer harness or module supply/ground
  • Loss of CAN/LIN communication between trailer module and vehicle network
  • Water ingress or corrosion of the trailer control module or connectors
  • Faulty trailer control module software or internal electronics

Symptoms

  • Trailer/tow functions inoperative or partially working (lights, indicators, brake lights)
  • Warning message or indicator on the instrument cluster related to trailer system
  • Trailer not detected by vehicle or tow assist features disabled
  • Intermittent trailer lighting or CAN-related warnings (multiple modules)
  • Possible related ABS/ESC warnings if trailer communications are required

What to check

  • Read all stored and pending DTCs with a manufacturer-level scan tool; record freeze-frame and related codes
  • Check vehicle battery voltage (while key on and cranking) to ensure adequate supply
  • Inspect fuses and relays for the trailer control module and associated power circuits
  • Visually inspect trailer connector at the hitch and module connectors for corrosion, bent pins, water or damage
  • Unplug trailer harness and check if the fault clears (isolates external trailer wiring)
  • Check module presence and communication on the CAN/LIN network using a scan tool (module should respond)

Signal parameters

  • Module supply voltage: approx. 11–14 V with ignition on
  • Module ground: near 0 Ω continuity to chassis ground
  • CAN high/low idle voltages: approx. 2.5 V common-mode, ~2.5 V/2.5 V with ~60–120 Ω differential when active
  • Trailer detection circuit resistance: varies by vehicle (check manufacturer spec for open/connected)
  • Indicator/stop lamp control outputs: should switch to supply voltage when activated
  • Wake/sleep messages on network when towing mode engaged (verify with diagnostic tool)

Diagnostic algorithm

  1. Connect a capable diagnostic tool and read all codes from body and powertrain modules; note related codes and freeze-frame data.
  2. Inspect the trailer connector and module connectors for corrosion, moisture, or bent pins; clean and reseat connectors.
  3. Check fuses/relays related to the trailer control module and replace if blown or suspect.
  4. With connector accessible, verify module supply voltage and ground at the module harness (ignition on).
  5. Unplug the trailer from the vehicle and clear the fault codes; test to see if code returns with trailer disconnected — if it does, problem is on-vehicle wiring or module.
  6. Verify CAN/LIN communications: confirm the trailer control module appears on the network and is responsive. Check for bus short/opens and other modules reporting communication errors.
  7. Perform continuity checks on trailer circuits (lights, turn, stop) from module to hitch; look for shorts to chassis or low resistance indicating wiring faults.
  8. If wiring and power/ground/CAN are verified good and a fault persists, check for available module software updates or reflash per manufacturer guidance.
  9. If module is confirmed faulty after all checks, replace the trailer control module and perform required programming/coding and function tests.
  10. After any repair, clear codes and road-test with and without trailer attached to confirm repair; re-check for related DTCs.

Likely causes

  • Corroded/damaged connector at the trailer hitch or module (common on tow harnesses)
  • Blown fuse or failed power/ground feed to the trailer control module
  • CAN bus communication fault preventing the module from reporting or responding
  • Internal failure of the trailer control module (less common than wiring/connectors)
  • Trailer short circuit or severe load on trailer lighting circuits causing module fault

Fault status

⚠️ Status
Trailer control module fault detected. The vehicle logged a fault with the trailer/tow module or its circuits; trailer functions may be reduced or disabled until repaired.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5 - 2.5 hours

Similar codes

B1400 B1401 B1406 B1408 B1410
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