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Home / DTC / C2304 — Chassis Control Module: CAN Bus Communication Fault

C2304 — Chassis Control Module: CAN Bus Communication Fault

Detailed page for trouble code C2304.

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C2304

Generic C — Chassis

Chassis Control Module: CAN Bus Communication Fault

Brand: Generic
Type: C — Chassis
Views: UK: 0 EN: 1 RU: 0
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Page language: EN

Causes

  • Open, short or high resistance in CAN_H or CAN_L wiring
  • Corroded, loose or damaged connectors at the CCM or other nodes
  • Missing or incorrect CAN termination resistors (open or shorted terminator)
  • Short to battery or ground on CAN wires
  • Low or intermittent battery voltage or poor ground(s) to CCM
  • A module on the CAN bus repeatedly going bus‑off or flooding the bus

Symptoms

  • Malfunction indicator or chassis/ABS/ESC warning lamps illuminated
  • Loss of CCM‑controlled features (e.g., stability control, traction control, ABS functions)
  • Diagnostic scanner cannot communicate with the CCM or shows intermittent responses
  • CAN network related messages or warnings in the instrument cluster
  • Erratic or non‑functional speedometer, braking assist, or related vehicle stability features

What to check

  • Scan with a capable diagnostic tool; record C2304 plus any other U/C/P/C codes and freeze‑frame data
  • Check for other modules reporting lost communication (note pattern of failures)
  • Visually inspect CAN wiring harness, connectors and CCM connector for corrosion, tightness, damage or rodent chew
  • Check battery voltage (stable ~12.6 V at rest, >= 11 V cranking) and main grounds to the CCM
  • Backprobe CAN_H and CAN_L at the CCM connector and at other nodes to confirm presence and continuity
  • Measure resistance across CAN_H and CAN_L with ignition off (expected ~60 Ω total with both terminators present)

Signal parameters

  • CAN bus idle (recessive): CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (both lines near mid‑rail)
  • CAN bus dominant: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (differential ≈ 2.0 V)
  • Expected DC resistance between CAN_H and CAN_L with both terminators present: ~60 Ω (two 120 Ω terminators in parallel)
  • Common CAN bus speeds: 125 kbps, 250 kbps, 500 kbps (verify vehicle‑specific bit rate)
  • Look for frequent bus errors, an abnormally low or high differential voltage, or a node repeatedly sending error frames

Diagnostic algorithm

  1. Connect a professional scan tool, read DTCs and freeze frame; note related U/C/P codes and time of occurrence.
  2. Inspect battery, main power and ground connections for the CCM; clean and tighten as needed.
  3. Visually inspect CCM connector and CAN wiring for damage, corrosion or pin push‑outs; repair any physical issues.
  4. With ignition on, backprobe CAN_H and CAN_L at the CCM and at another known good node to verify expected idle voltages and differential behavior.
  5. With ignition on, measure DC resistance across CAN_H and CAN_L with ignition off. Compare to ~60 Ω; open or short indicates wiring/terminator problems.
  6. Use a scope or CAN bus analyzer to monitor traffic for error frames, a stuck dominant state, or a node repeatedly going bus‑off. If a single node floods the bus, disconnect nodes one at a time to isolate.
  7. Disconnect any aftermarket modules or trailer harnesses and retest communication.
  8. Repair wiring/connector faults or replace failed terminators; retest. If wiring and termination are good, swap CCM with a known good unit only after verifying software/calibration compatibility.
  9. Clear codes, perform a road test while monitoring CAN traffic and DTCs to confirm repair. If intermittent, stress test (vibration, wiggle, temperature) to reproduce.
  10. If hardware checks pass, check for manufacturer software updates or TSBs and consider module reprogramming or replacement as final steps.

Likely causes

  • Damaged wiring or connector at or near the CCM (most common)
  • Bad or missing termination (open/shorted 120 Ω resistors) causing abnormal voltages
  • Faulty CCM or another module repeatedly going bus‑off and preventing communication
  • Intermittent battery/ground problem causing module resets and communication loss
  • Aftermarket device or trailer harness improperly tied into the CAN bus

Fault status

⚠️ Status
Chassis Control Module reports a CAN bus communication fault — communications to or from the CCM are intermittent or lost. Inspect CAN wiring, terminators, power/ground and other modules on the bus.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours

Similar codes

U0073 U0100 U0121 U0140 C1201
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