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Home / DTC / B1C81 — rear pump wash relay circuit output

B1C81 — rear pump wash relay circuit output

Detailed page for trouble code B1C81.

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Code

B1C81

LAND ROVER B — Body

rear pump wash relay circuit output

Brand: LAND ROVER
Type: B — Body
Views: UK: 7 EN: 14 RU: 12
AI status
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Page language: EN

Causes

  • Faulty rear wash pump relay
  • Open, short or high-resistance wiring between module, relay and pump
  • Corroded/damaged connector at pump, relay or module
  • Failed rear washer pump (seized or electrically shorted)
  • Blown fuse protecting the pump circuit
  • Poor or missing ground at pump or relay ground point

Symptoms

  • Rear washer (rear window) does not operate when selected
  • Intermittent rear washer operation
  • Washer pump runs only when engine off/ignition off or behaves unusually
  • Fuse related to washer circuit blown repeatedly
  • DTC B1C81 stored in BCM and possibly warning message on dash
  • No audible pump noise when activated or unusual noise from pump area

What to check

  • Read and record freeze frame and related codes with a diagnostic scan tool
  • Inspect fuses for the washer pump circuit and replace if blown; note if it blows again
  • Visually inspect relay, relay socket and harness for corrosion, water ingress, damage or loose pins
  • Attempt to operate rear washer using diagnostic actuator function and note behavior
  • Measure voltage at relay output terminal/connector while command is active and inactive
  • Check continuity/voltage at pump connector and measure resistance of pump motor (with connector disconnected)

Signal parameters

  • Relay output to pump when commanded: approx. battery voltage (~11–14 V typical) at the pump supply terminal (varies by vehicle and battery state)
  • Relay output when not commanded: near 0 V or open circuit at pump supply terminal
  • Expected pump current while running: typically in the low amps range (commonly 1–5 A for washer pumps; refer to service data for exact value)
  • Pump motor DC resistance (motor winding): low ohm value when measured at connector; compare with service specification
  • Module driver behaviour: diagnostic request should show the BCM commanding the relay output state (On/Off) in the scan tool

Diagnostic algorithm

  1. Connect an OEM-level scan tool and read stored codes and freeze frame data; record related body/lighting modules data.
  2. Visual inspection: open trunk/panel to access rear washer pump, relay and wiring. Look for water ingress, corrosion, damaged insulation or rodent damage.
  3. Check fuses protecting the washer pump circuit. Replace only if blown and do not continue without determining cause if it blows again.
  4. Use the scan tool to command the rear washer pump relay ON while a second person monitors the pump area for noise or movement.
  5. With the relay commanded ON, measure voltage at the relay output terminal and at the pump connector positive terminal. Expect battery voltage when commanded.
  6. If no voltage at pump connector but voltage at relay socket, check continuity between relay output and pump connector; repair any open or high-resistance wiring.
  7. Disconnect pump and bench-test it by applying battery voltage directly (observe current draw and proper operation). If pump does not run or draws excessive current, replace the pump.
  8. Measure resistance of the pump motor windings (compare to service data). Very low, very high, or infinite resistance indicate motor fault.
  9. Check ground: with circuit de-energized, verify continuity from pump ground to chassis ground and from relay ground to chassis ground.
  10. Test or swap the relay with a known good relay of the same type and re-check operation. If relay socket contacts are damaged, repair/replace.
  11. If wiring, relay and pump test OK but the BCM does not command the output or commands incorrectly, diagnose BCM driver circuit or software; consult manufacturer service information before replacing BCM.
  12. After repairs, clear codes and perform functional test of rear washer multiple times. Road-test or operate module cycles to confirm repair and ensure fuse does not blow.

Likely causes

  • Failed relay or relay socket
  • Damaged wiring/connector (chafing, corrosion, broken pin) between BCM and relay/pump
  • Rear washer pump motor failure or seized impeller increasing current draw
  • Blown fuse or fusible link upstream of pump
  • Corroded ground connection causing intermittent/weak circuit return

Fault status

⚠️ Status
Rear pump wash relay circuit output — abnormal relay output detected by control module.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

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B1C80 B1C82 B1C83 B1C8A B1C8B
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