Code
C2356
HYUNDAI
C — Chassis
Rear Supply/Exhaust Valve
Views:
UK: 18
EN: 21
RU: 17
AI status
Completed
Completed
100%
Causes
- Open or shorted wiring in the rear supply/exhaust valve circuit
- Poor or corroded connector at the valve or module
- Failed rear supply/exhaust solenoid valve (stuck, internal short, or mechanical failure)
- Faulty ABS/ESC control module or driver transistor
- Low or contaminated brake fluid or hydraulic blockage preventing valve movement
- Blown fuse or poor battery/ground supply to the valve circuit
Symptoms
- ABS or ESC warning lamp illuminated
- Traction/stability control reduced or disabled
- Altered brake feel during ABS activation (pulsation or reduced modulation)
- Possible reduced braking performance during emergency events
- DTC C2356 stored in brake/ESC module; possible related codes present
What to check
- Read and record freeze-frame data and all related ABS/ESC codes with a capable scan tool
- Visually inspect wiring harness and connector at the rear supply/exhaust valve for damage, corrosion, or loose terminals
- Check vehicle battery voltage and ground integrity before doing electrical tests
- Inspect brake fluid level and condition; check for contamination or air in hydraulic circuit
- Perform resistance and continuity checks on the valve connector pins per service manual
- Use scan tool to command the valve and observe response (actuation test) while monitoring live data
Signal parameters
- Typical solenoid coil resistance (example): 2–20 ohms (manufacturer-specific — consult service data)
- Resting voltage at valve connector: battery voltage (~12 V) on supply circuit
- Command signal: PWM or switched ground from ABS/ESC module — duty cycle varies with command
- Activation current: depends on valve coil (example range 0.5–5 A) — monitor with clamp meter when safe
- No high-voltage signals expected; all tests should be done with vehicle electrical system powered per service procedures
Diagnostic algorithm
- Connect a diagnostic scan tool, record C2356 plus any related codes and freeze-frame data.
- Inspect the valve connector and wiring for corrosion, damage, crushed wires, or loose pins. Repair as needed.
- Verify battery voltage and good chassis ground. Repair poor battery/ground connections before further testing.
- With ignition on (engine off) measure resistance across the valve coil according to service data. Compare to specification.
- Check for continuity to the ABS/ESC module and for short to ground/power. Repair any wiring faults found.
- Use the scan tool’s actuator function to command the rear supply/exhaust valve while observing connector voltage and current. Listen/feel for valve operation.
- If the valve does not respond electrically but wiring is good, bench-test or replace the valve and re-test.
- If wiring and valve check OK, suspect ABS/ESC control module output driver; verify module operation and update software or replace per factory procedures.
- After repairs, clear codes, perform relearn/bleed procedures if hydraulic components were opened, and road-test to confirm the issue is resolved.
Likely causes
- Damaged wiring or connector to the rear valve (moisture/corrosion or chafing)
- Failed rear supply/exhaust solenoid valve
- Loss of power or ground to the valve circuit
- Faulty ABS/ESC control module output for the valve
Fault status
Status
C2356 — Rear Supply/Exhaust Valve: electrical or functional fault detected in the rear brake supply/exhaust valve circuit. Inspect wiring, connectors, valve, and ABS/ESC module.
Repair difficulty: Medium
Diagnostic time: 0.5-2.5 hours
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