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Home / DTC / B1901 — Communication error of compass

B1901 — Communication error of compass

Detailed page for trouble code B1901.

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Code

B1901

MITSUBISHI B — Body

Communication error of compass

Brand: MITSUBISHI
Type: B — Body
Views: UK: 4 EN: 14 RU: 10
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Loss of communication on vehicle network (CAN or LIN) between compass module and cluster/BCM
  • Faulty compass module or internal failure
  • Open or shorted wiring or connector between compass sensor/module and harness
  • Poor power supply or ground to the compass module
  • Corroded or poorly seated connectors (roof, mirror area, dash)
  • Aftermarket equipment or nearby electromagnetic interference

Symptoms

  • Compass heading not displayed or displays N/A/— on cluster or navigation screen
  • Intermittent or inconsistent compass readings
  • Related warning message on the instrument cluster or infotainment
  • Possible other network communication faults or sporadic module behavior
  • No faults in other systems aside from compass-related functions (in some cases)

What to check

  • Read and record all stored codes from all modules with a manufacturer-level scan tool
  • Check for additional U-codes (network communication) that indicate bus issues
  • Visually inspect connectors and wiring to the compass sensor (typically in roof or near mirror) and instrument cluster
  • Verify fuses and power/ground circuits for the compass module
  • Check for recent aftermarket installations (alarms, remote start) that could affect bus wiring
  • Inspect for water ingress or corrosion in related harness areas

Signal parameters

  • Battery supply to module: approx. 11–14 V with ignition on
  • Module reference supply (if used): approx. 5 V (check manufacturer spec)
  • CAN bus idle voltages: roughly mid-rail (~2.5 V) on CAN_H and CAN_L (verify with factory data)
  • LIN bus: idle voltage per manufacturer specification (often near supply or ground depending on topology)
  • Communication activity: presence of data frames when monitored with a scan tool or oscilloscope
  • Continuity/resistance: wiring to module should show near-zero ohms to connected pins (no opens)

Diagnostic algorithm

  1. Connect a capable diagnostic scan tool and read all DTCs from all modules; note related U- or B-codes and freeze-frame data.
  2. Attempt to clear B1901, then observe whether the code returns and under what conditions (startup, after driving, after door open).
  3. Inspect wiring and connectors at the compass sensor (often in overhead console or behind windshield/mirror) and at the instrument cluster; reseat connectors and look for corrosion or damage.
  4. Verify power and ground to the compass module: check fuses, measure supply voltage with ignition on, and test ground continuity to chassis.
  5. Check vehicle communication bus health: use scan tool to monitor CAN/LIN traffic and see if the compass module is present and transmitting. Look for other modules showing lost communication.
  6. If bus activity is abnormal, isolate by disconnecting suspected modules or aftermarket devices and re-check the bus; inspect wiring for shorts to power or ground.
  7. Use an oscilloscope or factory data to validate proper signaling on communication lines (idle voltages, waveform, differential activity).
  8. If wiring, power and bus are confirmed good but the module does not communicate, consider reflashing/updating module software per manufacturer bulletin, or replace the compass module or associated control unit as a next step.
  9. After any repair, clear codes and verify proper function and that the code does not return under normal operating conditions.

Likely causes

  • Loose, corroded or disconnected connector at the compass sensor or instrument cluster
  • Open/short in the communication line (CAN/LIN) or damaged wiring harness near the A-pillar/roof
  • Loss of power or ground to the compass module (fuse, splice, or ground point)
  • Faulty compass module or instrument cluster module not transmitting/receiving data
  • Network bus fault caused by another module or aftermarket device

Fault status

⚠️ Status
Compass module communication error — compass data unavailable or not received by network/instrument cluster.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-3.0 hours

Similar codes

B1900 B1902 U0073 U0100 U0140
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Code

B1901

Other B — Body

Air Bag Crash Sensor #1 Feed/Return Circuit Short To Ground

Brand: Other
Type: B — Body
Views: UK: 13 EN: 36 RU: 27
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Loss of communication on vehicle network (CAN or LIN) between compass module and cluster/BCM
  • Faulty compass module or internal failure
  • Open or shorted wiring or connector between compass sensor/module and harness
  • Poor power supply or ground to the compass module
  • Corroded or poorly seated connectors (roof, mirror area, dash)
  • Aftermarket equipment or nearby electromagnetic interference

Symptoms

  • Compass heading not displayed or displays N/A/— on cluster or navigation screen
  • Intermittent or inconsistent compass readings
  • Related warning message on the instrument cluster or infotainment
  • Possible other network communication faults or sporadic module behavior
  • No faults in other systems aside from compass-related functions (in some cases)

What to check

  • Read and record all stored codes from all modules with a manufacturer-level scan tool
  • Check for additional U-codes (network communication) that indicate bus issues
  • Visually inspect connectors and wiring to the compass sensor (typically in roof or near mirror) and instrument cluster
  • Verify fuses and power/ground circuits for the compass module
  • Check for recent aftermarket installations (alarms, remote start) that could affect bus wiring
  • Inspect for water ingress or corrosion in related harness areas

Signal parameters

  • Battery supply to module: approx. 11–14 V with ignition on
  • Module reference supply (if used): approx. 5 V (check manufacturer spec)
  • CAN bus idle voltages: roughly mid-rail (~2.5 V) on CAN_H and CAN_L (verify with factory data)
  • LIN bus: idle voltage per manufacturer specification (often near supply or ground depending on topology)
  • Communication activity: presence of data frames when monitored with a scan tool or oscilloscope
  • Continuity/resistance: wiring to module should show near-zero ohms to connected pins (no opens)

Diagnostic algorithm

  1. Connect a capable diagnostic scan tool and read all DTCs from all modules; note related U- or B-codes and freeze-frame data.
  2. Attempt to clear B1901, then observe whether the code returns and under what conditions (startup, after driving, after door open).
  3. Inspect wiring and connectors at the compass sensor (often in overhead console or behind windshield/mirror) and at the instrument cluster; reseat connectors and look for corrosion or damage.
  4. Verify power and ground to the compass module: check fuses, measure supply voltage with ignition on, and test ground continuity to chassis.
  5. Check vehicle communication bus health: use scan tool to monitor CAN/LIN traffic and see if the compass module is present and transmitting. Look for other modules showing lost communication.
  6. If bus activity is abnormal, isolate by disconnecting suspected modules or aftermarket devices and re-check the bus; inspect wiring for shorts to power or ground.
  7. Use an oscilloscope or factory data to validate proper signaling on communication lines (idle voltages, waveform, differential activity).
  8. If wiring, power and bus are confirmed good but the module does not communicate, consider reflashing/updating module software per manufacturer bulletin, or replace the compass module or associated control unit as a next step.
  9. After any repair, clear codes and verify proper function and that the code does not return under normal operating conditions.

Likely causes

  • Loose, corroded or disconnected connector at the compass sensor or instrument cluster
  • Open/short in the communication line (CAN/LIN) or damaged wiring harness near the A-pillar/roof
  • Loss of power or ground to the compass module (fuse, splice, or ground point)
  • Faulty compass module or instrument cluster module not transmitting/receiving data
  • Network bus fault caused by another module or aftermarket device

Fault status

⚠️ Status
Compass module communication error — compass data unavailable or not received by network/instrument cluster.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-3.0 hours

Similar codes

B1900 B1902 U0073 U0100 U0140
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