C1093

Code

ALFA ROMEO C — Chassis

Right rear discharge valve

Brand: ALFA ROMEO

Type: C — Chassis

Views: UK: 6 EN: 14 RU: 9

AI status

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Page language: EN

ABS/ESP warning light illuminated
Traction control and/or stability functions limited or disabled
Brake feel changes during ABS intervention (pulsing or prolonged pedal action)
Stored DTC for right rear discharge valve and possible related ABS codes
Occasional or persistent ABS pump activity or unusual noises during braking events

Read and record freeze-frame and all stored ABS/ESP codes with a capable scan tool
Visual inspection of wiring and connector at the right rear discharge valve for damage, corrosion or water ingress
Check battery voltage and main/ABS fuses and relays
Backprobe valve connector and measure voltage/ground while commanding the valve with a diagnostic scan tool
Measure coil resistance with connector disconnected and compare to OEM specification (or left-side valve for reference)
Wiggle-test wiring while monitoring live data for intermittent faults

Control is typically a switched/pulsed signal from ABS/ESP module (PWM or on/off driver); expect a modulated duty response when commanded
Static coil resistance: typically low (single-digit to low tens of ohms) — verify against OEM spec; large deviation indicates open or short
Supply voltage at connector with system ON: near battery voltage when commanded; ground reference should be solid
When commanded, backprobe may show a pulsed voltage or duty-cycle modulation rather than a steady DC level (refer to OEM diagnostic data)
No or erratic signal while commanding indicates wiring/driver or module fault

Retrieve all codes and note freeze-frame data. Confirm C1093 is current and check for related codes (wheel speed sensors, pump, other valve codes).
Perform a visual inspection of the right rear valve connector and wiring harness for corrosion, damage, pin push-out, or water intrusion. Repair any obvious issues.
Verify battery voltage (12.6 V nominal) and proper fusing/relay for the ABS/ESP system.
With connector attached, command the right rear discharge valve ON/OFF from a scan tool while monitoring voltage at the valve connector. Observe for a change in voltage or PWM signal.
Disconnect connector and measure coil resistance across valve terminals. Compare to OEM spec or the left rear valve as a reference. An open or shorted reading indicates a faulty valve.
If wiring appears suspect, perform continuity and resistance checks from the valve connector back to the ABS module, checking for opens, shorts to ground, or power shorts.
Wiggle wiring and connectors while monitoring live data for intermittent changes. Repair harness or connector as required (repair with proper sealing and protection).
If wiring and valve are good but no proper control signal is present, suspect the ABS/ESP module driver. Further module-level testing or replacement may be required.
After repairs, clear codes and perform a road/functional test to ensure the fault does not return and system operates normally.

⚠️ Status

ABS/ESP fault: Right rear discharge valve circuit malfunction. Check wiring, connector, and valve.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-2.5 hours

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