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Home / DTC / B1548 — CAN No communication

B1548 — CAN No communication

Detailed page for trouble code B1548.

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Code

B1548

MITSUBISHI B — Body

CAN No communication

Brand: MITSUBISHI
Type: B — Body
Views: UK: 9 EN: 11 RU: 8
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or shorted CAN bus wiring (CAN High or CAN Low)
  • Failed or powered-down control module on the bus
  • Missing or failed termination resistor(s) on the CAN bus
  • Blown fuse or loss of power/ground to one or more modules
  • Corroded or loose connectors, broken pins at modules or junctions
  • Aftermarket electronic device interfering with the bus (alarm, radio, tracker)

Symptoms

  • One or more control modules not responding to scan tool (no communication)
  • Multiple dashboard warning lamps illuminated or intermittent instrument cluster operation
  • Loss of functions tied to affected modules (ABS, SRS lights, HVAC, gauges, immobilizer)
  • Intermittent or permanent failure of networked systems
  • Diagnostic trouble codes stored for multiple modules or U-codes indicating lost communication

What to check

  • Use a capable scan tool to read stored DTCs from all modules and note any U-codes
  • Visually inspect all CAN-related fuses and relays; confirm battery voltage and good chassis/engine ground
  • Inspect wiring harnesses, connectors and junction blocks for corrosion, bent pins, breaks, or water intrusion near the instrument panel and BCM
  • Measure CAN termination resistance between CAN High and CAN Low at a convenient connector (should be ~60 ohms with ignition off)
  • Check for back-probed voltages on CAN High and CAN Low with ignition ON (see signal_params)
  • Disconnect/remove any recently installed aftermarket devices connected to the vehicle network

Signal parameters

  • CAN idle voltage (to battery ground): CAN High ≈ 2.5 V, CAN Low ≈ 2.5 V (both center at ~2.5V)
  • Dominant/Active voltages during data: CAN High ≈ 3.5 V, CAN Low ≈ 1.5 V (voltage difference present)
  • Termination resistance across CAN H and CAN L: approx. 60 ohms (two 120 Ω terminators in parallel)
  • Short to battery/ground will show CAN lines pulled toward 12 V or 0 V respectively
  • Bus activity: valid periodic CAN traffic visible on a scope or CAN monitor at expected bitrate (commonly 250 kb/s or 500 kb/s on vehicle networks)

Diagnostic algorithm

  1. Connect a diagnostic scan tool and record all modules’ DTCs and network status (note any U-codes).
  2. Verify battery voltage is stable (12.4–12.8 V) and check main power/ground circuits to suspected modules.
  3. Inspect and test CAN bus fuses and relays; replace any blown fuses and retest communication.
  4. Visually inspect connectors and harnesses along the CAN backbone (instrument panel, BCM, junction boxes). Repair any damaged wiring or corroded pins.
  5. Measure termination resistance across CAN H and CAN L at a known good connector; if not ≈60 Ω, locate missing/bad terminator or open circuit.
  6. With ignition ON, measure CAN High and CAN Low voltages at the affected module(s). Compare to expected idle voltages (~2.5 V).
  7. If voltages are abnormal, isolate the fault by disconnecting modules one at a time (start at ends of the bus) and observe when communications return to identify the offending segment or module.
  8. Use an oscilloscope or CAN bus analyzer to confirm packet traffic and to identify noise, stuck dominant states, or low amplitude signals.
  9. If a module is found to be unresponsive but wiring and bus integrity are good, follow manufacturer procedure for module reset or replacement; reprogram or reinitialize as required.
  10. After repair, clear DTCs, verify all modules respond, and perform a road test or network exercise to confirm stability.

Likely causes

  • Blown CAN fuse or loss of ground to the affected module
  • Damaged/shorted CAN High or CAN Low wiring near BCM or junction connectors
  • Detached or corroded connector at the affected control module
  • Failed instrument cluster/BCM preventing bus communications
  • Incorrect aftermarket device wiring connected to CAN lines

Fault status

⚠️ Status
No CAN communication detected by a control module. Networked modules may be unavailable until wiring, power/ground, or the faulty module is repaired.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1-3 hours

Similar codes

U0100 U0073 U0155 U0121 B1547
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Code

B1548

Other B — Body

Power Window Master Circuit Open

Brand: Other
Type: B — Body
Views: UK: 23 EN: 23 RU: 22
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or shorted CAN bus wiring (CAN High or CAN Low)
  • Failed or powered-down control module on the bus
  • Missing or failed termination resistor(s) on the CAN bus
  • Blown fuse or loss of power/ground to one or more modules
  • Corroded or loose connectors, broken pins at modules or junctions
  • Aftermarket electronic device interfering with the bus (alarm, radio, tracker)

Symptoms

  • One or more control modules not responding to scan tool (no communication)
  • Multiple dashboard warning lamps illuminated or intermittent instrument cluster operation
  • Loss of functions tied to affected modules (ABS, SRS lights, HVAC, gauges, immobilizer)
  • Intermittent or permanent failure of networked systems
  • Diagnostic trouble codes stored for multiple modules or U-codes indicating lost communication

What to check

  • Use a capable scan tool to read stored DTCs from all modules and note any U-codes
  • Visually inspect all CAN-related fuses and relays; confirm battery voltage and good chassis/engine ground
  • Inspect wiring harnesses, connectors and junction blocks for corrosion, bent pins, breaks, or water intrusion near the instrument panel and BCM
  • Measure CAN termination resistance between CAN High and CAN Low at a convenient connector (should be ~60 ohms with ignition off)
  • Check for back-probed voltages on CAN High and CAN Low with ignition ON (see signal_params)
  • Disconnect/remove any recently installed aftermarket devices connected to the vehicle network

Signal parameters

  • CAN idle voltage (to battery ground): CAN High ≈ 2.5 V, CAN Low ≈ 2.5 V (both center at ~2.5V)
  • Dominant/Active voltages during data: CAN High ≈ 3.5 V, CAN Low ≈ 1.5 V (voltage difference present)
  • Termination resistance across CAN H and CAN L: approx. 60 ohms (two 120 Ω terminators in parallel)
  • Short to battery/ground will show CAN lines pulled toward 12 V or 0 V respectively
  • Bus activity: valid periodic CAN traffic visible on a scope or CAN monitor at expected bitrate (commonly 250 kb/s or 500 kb/s on vehicle networks)

Diagnostic algorithm

  1. Connect a diagnostic scan tool and record all modules’ DTCs and network status (note any U-codes).
  2. Verify battery voltage is stable (12.4–12.8 V) and check main power/ground circuits to suspected modules.
  3. Inspect and test CAN bus fuses and relays; replace any blown fuses and retest communication.
  4. Visually inspect connectors and harnesses along the CAN backbone (instrument panel, BCM, junction boxes). Repair any damaged wiring or corroded pins.
  5. Measure termination resistance across CAN H and CAN L at a known good connector; if not ≈60 Ω, locate missing/bad terminator or open circuit.
  6. With ignition ON, measure CAN High and CAN Low voltages at the affected module(s). Compare to expected idle voltages (~2.5 V).
  7. If voltages are abnormal, isolate the fault by disconnecting modules one at a time (start at ends of the bus) and observe when communications return to identify the offending segment or module.
  8. Use an oscilloscope or CAN bus analyzer to confirm packet traffic and to identify noise, stuck dominant states, or low amplitude signals.
  9. If a module is found to be unresponsive but wiring and bus integrity are good, follow manufacturer procedure for module reset or replacement; reprogram or reinitialize as required.
  10. After repair, clear DTCs, verify all modules respond, and perform a road test or network exercise to confirm stability.

Likely causes

  • Blown CAN fuse or loss of ground to the affected module
  • Damaged/shorted CAN High or CAN Low wiring near BCM or junction connectors
  • Detached or corroded connector at the affected control module
  • Failed instrument cluster/BCM preventing bus communications
  • Incorrect aftermarket device wiring connected to CAN lines

Fault status

⚠️ Status
No CAN communication detected by a control module. Networked modules may be unavailable until wiring, power/ground, or the faulty module is repaired.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1-3 hours

Similar codes

U0100 U0073 U0155 U0121 B1547
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