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Home / DTC / B1275 — Potentiometer of the ventilation servo motor - short circuit to ground

B1275 — Potentiometer of the ventilation servo motor - short circuit to ground

Detailed page for trouble code B1275.

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Code

B1275

LAND ROVER B — Body

Potentiometer of the ventilation servo motor - short circuit to ground

Brand: LAND ROVER
Type: B — Body
Views: UK: 5 EN: 13 RU: 8
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Page language: EN

Causes

  • Damaged or chafed wiring harness shorting the potentiometer signal to ground
  • Corroded, bent or pushed-back connector pins causing a ground short
  • Failed ventilation servo motor / integrated potentiometer (internal short)
  • Water ingress or contamination in actuator or connector
  • Poor ground or body damage causing unintended continuity to chassis
  • Faulty HVAC control module (rare)

Symptoms

  • HVAC vent door(s) stuck, not moving or in wrong position
  • HVAC mode/airflow selector not following commands
  • DTC B1275 (potentiometer short to ground) stored in climate control module
  • Inaccurate actuator position reading on a scan tool (signal near 0 V)
  • Intermittent operation or loss of control after moisture exposure

What to check

  • Read DTC(s) with a diagnostic scanner and note freeze-frame/live data for the HVAC actuator position PID
  • Attempt to command the vent/door from the scanner and watch the potentiometer/position feedback value
  • Visually inspect actuator, connector and wiring for damage, corrosion, water ingress and pin push-out
  • Back-probe the actuator connector with ignition on and measure reference and signal voltages
  • With harness disconnected, check continuity between the potentiometer signal pin and chassis ground (should be open)
  • Wiggle the harness and connectors while observing live data to check for intermittent shorts

Signal parameters

  • Reference (supply) voltage: typically ~5.0 V (present at actuator reference pin with ignition/ACU powered)
  • Potentiometer signal voltage: variable ~0.5–5.0 V depending on door position; a short to ground will show ≈0 V
  • Potentiometer resistance: typically in the low kilo-ohm range (manufacturer-specific) between end terminals; signal pin will vary between ends

Diagnostic algorithm

  1. Connect a scan tool, record DTC B1275 and HVAC actuator live data; attempt to command actuator and observe signal value.
  2. Perform visual inspection of actuator, wiring and connector for damage, corrosion, water ingress and pin damage at the dash/bulkhead.
  3. With ignition ON, back-probe the connector: verify reference (≈5 V) and measure the potentiometer signal voltage while commanding the actuator. If signal is ≈0 V constantly, suspect short to ground.
  4. Turn ignition OFF and disconnect actuator connector. Using a multimeter in continuity mode, check between signal pin and chassis ground. Continuity (near 0 Ω) indicates a short to ground in harness or actuator.
  5. If there is no continuity with the connector disconnected, perform harness isolation: inspect wiring runs, remove trim as needed and test continuity from the signal pin at the actuator connector back to the control module and for unintended grounds (shorts) to chassis.
  6. If wiring checks good, reconnect actuator and swap with a known-good actuator (if available) or install a replacement actuator to confirm fault follows the part.
  7. After repair, clear DTCs, re-test actuator operation and verify no return of the fault.
  8. If wiring and actuator are good but fault persists, inspect/replace HVAC control module or its connector as a last step (rare).

Likely causes

  • Wiring harness damage at actuator or through bulkhead
  • Failed/internally shorted HVAC servo motor potentiometer
  • Corroded or contaminated connector at the actuator

Fault status

⚠️ Status
Stored: Potentiometer/position sensor circuit for ventilation servo motor detected short to ground (signal ~0 V).
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

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