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Home / DTC / B2994 — Main cylinder open:open line

B2994 — Main cylinder open:open line

Detailed page for trouble code B2994.

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Code

B2994

MITSUBISHI B — Body

Main cylinder open:open line

Brand: MITSUBISHI
Type: B — Body
AI status
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Page language: EN

Causes

  • Broken or chafed wiring in the main cylinder harness
  • Disconnected or corroded connector at main cylinder or control module
  • Blown fuse or failed relay supplying the main cylinder circuit
  • Failed main cylinder assembly (sensor or solenoid)
  • Poor or corroded ground at related ground point
  • Water intrusion or damage from previous repairs

Symptoms

  • ABS warning lamp and/or brake warning lamp illuminated
  • Traction control/ESC warning lamp may be on
  • Reduced or altered ABS/brake assist function; increased stopping distance in ABS events
  • Possible parking brake or brake system self-test faults
  • Diagnostic trouble codes related to brake hydraulic control or communications present

What to check

  • Retrieve freeze frame data and full DTC list with a capable scan tool (ABS/BCM/TCU as applicable)
  • Visually inspect wiring and connectors at the main cylinder and the ABS/hydraulic unit for damage, corrosion, pushed-out pins, or moisture
  • Check fuses and relays for the braking/ABS circuits
  • With ignition on, measure battery voltage at the power pin of the main cylinder connector
  • Check for good ground at the main cylinder ground pin(s)
  • Perform continuity check from the main cylinder connector to the ABS/control module connector to find an open/high resistance

Signal parameters

  • Power pin: approx. battery voltage with ignition ON (check factory spec)
  • Ground: near 0 ohms continuity to chassis ground
  • Sensor signal: typically a low-voltage analog signal (factory spec often ~0.5–4.5 V depending on pressure) — verify against service manual
  • Solenoid coil: low-ohm resistance when measured across coil terminals (see factory spec); infinite/open indicates an open coil
  • Continuity: wiring circuit should show near 0 ohms between related connectors (no open)

Diagnostic algorithm

  1. Connect a diagnostic scanner and confirm B2994 plus any related codes; note freeze-frame and live data. 2. Visually inspect the main cylinder connector and wiring for damage, corrosion, or disconnection. 3. Verify applicable fuses/relays are good. 4. With the ignition ON (engine off), measure voltage at the main cylinder power terminal and verify a good ground at ground terminal. 5. Perform continuity/resistance check from main cylinder connector to the ABS/hydraulic unit connector; repair any open circuits or high-resistance joints. 6. If power/ground/wiring are good, measure sensor output or coil resistance at the main cylinder; compare to factory specification. 7. If main cylinder internal component is out of spec, replace the main cylinder assembly. 8. After repairs, clear codes and perform a road or system test; re-check for recurrence. 9. If fault persists and wiring and actuator are confirmed good, refer to the ABS/BCM wiring diagram and consider module-level diagnostics or replacement per factory manual.

Likely causes

  • Disconnected or loose connector at main cylinder
  • Open or damaged wire between main cylinder and ABS or body control module
  • Corroded pins in the connector
  • Failed main cylinder internal sensor or solenoid element
  • Blown fuse supplying the circuit

Fault status

⚠️ Status
Open circuit detected on the main cylinder control/sensor line. Control module has logged a circuit-open condition; brake/ABS functions may be degraded until the wiring or component is repaired.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours

Similar codes

B2993 B2995 C1210 C1256 U0121
406

Browse 406 MITSUBISHI manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

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