C1093

Code

FIAT C — Chassis

Right rear discharge valve

Brand: FIAT

Type: C — Chassis

Views: UK: 3 EN: 10 RU: 6

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Page language: EN

Causes

Open or short in the valve solenoid wiring (right rear discharge valve)
Corroded, loose or damaged connector at the valve or hydraulic unit
Failed right rear discharge valve solenoid (stuck, shorted or open coil)
Internal hydraulic fault in the ABS modulator (internal leakage or valve body failure)
Faulty ABS/ESP control module or driver circuit
Blown fuse or poor ground affecting module/valve power

Symptoms

ABS/ESP warning lamp illuminated on instrument cluster
Traction control or stability control disabled or limited
ABS may not operate correctly for the right rear wheel; unusual brake behavior
Possible brake pedal pulsation or reduced braking performance under ABS activation
One or more related fault codes stored in ABS/ESP module

What to check

Read and record ABS/ESP fault codes and freeze-frame data with a diagnostic scanner
Clear the code and test-drive to confirm repeatability
Visual inspection of wiring harness and connector for the right rear valve (signs of corrosion, damage, water ingress)
Check fuses and central junction power/ground for ABS/ESP module
Measure connector voltage and ground at rest and while commanding the valve with a scan tool
Measure solenoid coil resistance at the valve connector (compare to factory spec if available)

Signal parameters

Solenoid coil resistance (typical automotive solenoids commonly in low-ohm range; compare to factory spec)
Command voltage to valve connector when actuated (should show switching/PWM from module; typically pulsed 0–12 V)
Ground continuity to module and chassis ground
Module supply voltage at connector (battery voltage with ignition on)
Actuator response during scan-tool command (valve moves or changes current draw)
Current draw when commanded (increases when coil energized; abnormal very high or zero current indicates fault)

Diagnostic algorithm

Retrieve full ABS/ESP code list and freeze-frame data. Note any additional related codes (wheel speed sensors, other valves, module faults).
Attempt to clear C1093. If it returns immediately or after a short drive, proceed with diagnostic checks; intermittent codes suggest wiring/connector issues.
Visually inspect right rear valve harness and connector for corrosion, looseness, bent pins or water ingress. Repair or replace damaged connectors/cable ties as needed.
With ignition off, disconnect the valve connector and measure solenoid coil resistance across the connector pins. Compare to factory specification. Open or very high resistance suggests a failed coil; near-zero suggests short.
Check continuity from the valve connector back to the ABS module pins to rule out open/short in harness. Wiggle harness while monitoring continuity to find intermittent faults.
Reconnect and backprobe connector. With scanner, command the right rear discharge valve while observing voltage and current at the connector. Lack of correct switching voltage or no current when commanded points to wiring or module driver fault.
Inspect ABS hydraulic unit externally for leaks or damage. If wiring and solenoid test good but valve does not operate, suspect internal hydraulic valve failure or module driver defect.
If wiring and solenoid are faulty, repair or replace harness, connector or valve solenoid. If solenoid and harness test OK but valve still reports fault, evaluate ABS/ESP control module (possible replacement or module repair/reflash by specialist).
After repairs, clear codes and perform functional test/road test with scan tool to confirm the fault is resolved and that ABS/ESP functions properly.

Likely causes

Damaged connector or corroded terminal at the right rear valve
Failed solenoid coil (open circuit or incorrect resistance)
Broken/shorted wire in harness to right rear valve
Internal hydraulic valve failure in ABS modulator
Control module driver fault (less common than wiring/solenoid faults)

Fault status

⚠️ Status

Right rear discharge valve circuit malfunction detected. The ABS/ESP control unit reports the right rear valve is not responding within expected electrical/operational parameters (open, short, incorrect resistance, stuck or no command response). Recommend electrical checks of connector, wiring, solenoid coil, and actuator tests before considering hydraulic unit or module replacement.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0 - 2.5 hours

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