Toggle Side Panel

Shopping Cart

No products in the basket.

Shopping Cart

No products in the basket.

Close search
Home / DTC / B2409 — STL.unit comm.(No response)

B2409 — STL.unit comm.(No response)

Detailed page for trouble code B2409.

34,332codes
59brands
11,841generic
22,491specific
All codes P-codes (Powertrain) B-codes (Body) C-codes (Chassis) U-codes (Network/User) Tesla Alerts
Reset
Code

B2409

MITSUBISHI B — Body

STL.unit comm.(No response)

Brand: MITSUBISHI
Type: B — Body
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • STL module powered down or internally failed
  • Blown fuse or poor power/ground to the STL unit
  • Open, shorted or corroded wiring/connectors to the STL unit
  • Faulty or disconnected bus (CAN or LIN) wiring or termination
  • Faulty gateway, Body Control Module (BCM) or other network node preventing messages
  • Software mismatch or module configuration error after replacement or programming

Symptoms

  • DTC B2409 stored and fault/warning lamp may be illuminated
  • Functions provided by the STL unit inoperative or intermittent (depends on module role)
  • Vehicle may refuse to start or steering/lock functions may not operate (model-dependent)
  • Loss of features controlled by the STL unit or related modules
  • Multiple communication-related DTCs present

What to check

  • Retrieve all stored and pending codes from all modules; record freeze frame data
  • Check battery voltage (key on and cranking) and inspect relevant fuses/relays
  • Visually inspect the STL module connector and harness for corrosion, water ingress, or damage
  • Verify module power and ground with a DVOM at the module connector
  • Backprobe CAN/LIN communication lines at the STL connector and at a known-good node
  • Check for proper bus termination resistance (approximately 60 ohms across CAN_H and CAN_L for two 120 ohm resistors in parallel)

Signal parameters

  • CAN bus idle voltages (typical): CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V; differential ≈ 0 V
  • CAN dominant state (typical): CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V during frames
  • Typical CAN bus speed depends on system (commonly 250 kbps or 500 kbps on high-speed networks)
  • LIN bus idle: pulled up to battery voltage; dominant state pulls near 0.5 V
  • Expected: stable periodic messages from STL unit when module is functioning (use OEM data/scan tool to confirm message IDs and rates)

Diagnostic algorithm

  1. Connect a factory or capable aftermarket scan tool and attempt to communicate with the STL unit. Note error and inability to connect.
  2. Check battery voltage and relevant fuses for the STL circuit. Repair any low-voltage conditions before proceeding.
  3. Visually inspect the STL module connector and harness for damage, corrosion, bent pins or water intrusion. Repair as needed.
  4. With ignition ON, backprobe the STL module power and ground pins to confirm stable supply voltage and a good ground reference.
  5. Backprobe the communication lines at the STL module and at a known-good node. Observe with a scope or high-speed data logger for bus activity and valid voltage levels.
  6. Measure termination resistance across CAN_H and CAN_L with the bus isolated; expect ~60 ohms. Investigate if out of range.
  7. If bus signals are absent or corrupted, isolate the fault by disconnecting segments or modules and repeating checks (wiggle test harness while monitoring).
  8. If bus and supply are good but module does not respond, attempt to reflash/reprogram the module if recommended by OEM procedures, then retest communication.
  9. If reprogramming fails or module still does not respond, replace the STL unit and recheck system communication and functionality.
  10. Clear codes and perform a full functional test of affected systems and confirm no return of B2409.

Likely causes

  • Loss of supply voltage or ground at the STL module
  • Broken or high-resistance connector pin(s) at the STL unit
  • Vehicle data bus wiring fault (open/short to battery/ground or between CAN_H and CAN_L)
  • Failed STL unit (internal communications circuit)
  • Missing or incorrect module programming after service

Fault status

⚠️ Status
No response from STL unit on the vehicle network (communication timeout/lost comm).
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.5 - 3.0 hours

Similar codes

B2408 B2410 U0100 U0121 U0140 U0073
406

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

MITSUBISHI

Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email

Report

Harassment or bullying behavior
Contains mature or sensitive content
Contains misleading or false information
Contains abusive or derogatory content
Contains spam, fake content or potential malware

Block Member?

Please confirm you want to block this member.

You will no longer be able to:

  • See blocked member's posts
  • Mention this member in posts
  • Invite this member to groups
  • Message this member
  • Add this member as a connection

Please note: This action will also remove this member from your connections and send a report to the site admin. Please allow a few minutes for this process to complete.

Report

You have already reported this .