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Home / DTC / P1621 — Mau operation of the input circuit of the motor control module

P1621 — Mau operation of the input circuit of the motor control module

Detailed page for trouble code P1621.

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Code

P1621

LAND ROVER P — Powertrain

Mau operation of the input circuit of the motor control module

Brand: LAND ROVER
Type: P — Powertrain
Views: UK: 5 EN: 12 RU: 10
AI status
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Page language: EN

Causes

  • Open, shorted or corroded wiring in the input circuit to the motor control module
  • Poor or missing power supply or ground to the motor control module
  • Faulty connector or pin (corrosion, bent/broken pin, poor contact)
  • Intermittent connection (broken wire, chafing, water ingress)
  • Failed motor control module / actuator
  • Related sensor or switch providing invalid input

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • Loss or erratic operation of the system driven by the motor control module (e.g., actuator/motor behaviour)
  • Reduced system functionality or limp mode depending on affected circuit
  • Intermittent faults — problem may come and go
  • Stored freeze-frame or data showing abnormal input values

What to check

  • Read and record all stored codes and freeze-frame data with a capable scan tool
  • Confirm MIL is for P1621 and note occurrence count and conditions
  • Check battery voltage and charging system (low voltage can create spurious faults)
  • Visually inspect wiring, harness, and connectors around the motor control module and related sensors
  • Check fuses and power feeds to the motor control module and related circuits
  • Check module grounds for tightness and corrosion

Signal parameters

  • Power supply pin: battery voltage (~12 V) with key ON/engine running
  • Ignition-switched feed: present with key in RUN
  • Ground reference: near 0 V (
  • Input signal: expected digital state (0 V or ~5 V) or pulsed waveform depending on sensor/type
  • CAN/LIN: correct bus voltage levels and activity when scanned (CAN ~2.5 V idle differential on twisted pair with +/- signals)
  • Continuity: low resistance for power/ground (

Diagnostic algorithm

  1. Retrieve all DTCs and freeze-frame data; confirm P1621 is current or historic and note conditions when set.
  2. Check battery voltage and charging system; ensure battery >12.2 V during tests. Recharge or replace if weak.
  3. Visually inspect connectors and wiring to the motor control module and associated sensors for corrosion, damage, or water ingress. Repair any physical damage.
  4. Check fuses and power feeds to the module. Back-probe the power and ignition-switched pins to confirm stable voltage with key ON.
  5. Verify good ground(s) at the module: remove bolt, clean contact, and measure resistance to chassis (should be very low).
  6. With a scan tool, monitor the input signal(s) to the motor control module while operating the system; look for missing, noisy or out-of-range values.
  7. If input is a digital or PWM signal, use an oscilloscope to inspect waveform integrity and timing. Compare to known-good specifications.
  8. Perform continuity and short-to-power/ground checks on suspect wiring harness circuits. Repair any opens/shorts. Use pin-out diagrams where available.
  9. If wiring and connectors test good, verify module communications on CAN/LIN bus and check for other module faults that could affect inputs.
  10. If all circuits and communications check good and the fault persists, consider replacing the motor control module only after confirming root cause and reprogramming requirements.
  11. After repair, clear codes and perform a road test or reproduce conditions to confirm P1621 does not return.

Likely causes

  • Damaged harness or chafed wire on the MAU input circuit
  • Loose/corroded connector at the motor control module
  • Blown fuse or failed power supply to the module
  • Bad ground connection near module
  • Failed motor control module (rare compared with wiring/connector faults)
  • Intermittent sensor/switch feeding the MAU input

Fault status

⚠️ Status
Malfunction detected in input circuit to motor control module (MAU). Input signal missing, out-of-range or intermittent.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P1620 P1622 P0600 P0601 P0606
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