C1000
ChassisAbnormality in Stoplight Switch Circuit
On Mitsubishi models specifically, this code typically refers to a fault in the ABS hydraulic control unit or pump motor circuit. Different Mitsubishi models interpret it slightly differently, but it almost always means the ABS module isn't getting the response it expects from the hydraulic pump or its control circuit.
ⓘ Information only. This page provides general educational information about fault code C1000. We do not assess the urgency or safety implications of any specific fault. That requires in-person diagnosis by a qualified mechanic. Full terms.
Recommended next steps
Whether a fault is urgent, drivable, or routine depends entirely on the cause on a specific vehicle, and that can only be determined by a qualified mechanic with diagnostic equipment. If a warning light is illuminated, the most reliable next step is professional diagnosis.
What does C1000 mean?
C1000 is a Chassis (ABS, traction control, steering) fault code. It indicates: Abnormality in Stoplight Switch Circuit.
Symptoms commonly associated with this code
Symptoms that drivers often report alongside this code. Not all may apply to every case:
- • ABS warning light on the dashboard
- • Possibly traction control or stability control warnings as well
- • Brake pedal feel may be slightly different (firmer or with more travel)
- • ABS function disabled, the brakes still work but won't pulse during emergency stops
- • On Mitsubishi Outlander and Lancer particularly: this fault appears with several other ABS-related codes alongside
Possible causes
Causes commonly associated with C1000, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. Failed ABS pump motor (the most common cause on Mitsubishi cars at high mileage)
- 2. Worn motor brushes inside the ABS pump, on older Mitsubishi units, the brushes wear and the pump won't operate reliably
- 3. Damaged wiring to the ABS module, often where the loom passes through the engine bay
- 4. Connector at the ABS module corroded or backed out, the unit is in a wet environment
- 5. Failed ABS module entirely (last resort, expensive)
- 6. Battery voltage low (a weak battery affects ABS module operation more than people realise)
How mechanics typically diagnose
A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training.
- 1. Check battery voltage first, weak batteries cause intermittent ABS faults on Mitsubishi cars more than most makes
- 2. Read all stored codes alongside C1000, the pattern often points to a specific sensor or motor
- 3. Inspect the ABS module and its wiring for moisture, corrosion, or impact damage
- 4. Test ABS pump motor operation with a manufacturer-specific scan tool that can command the pump directly
- 5. If the pump won't run on command, the motor or its control circuit is the fault
- 6. ABS module repair specialists (BBA Reman, ECU Testing) can rebuild Mitsubishi ABS pumps for £150-£300 if the motor is the only fault
Common questions about C1000
Is the car safe to drive? +
Standard hydraulic brakes still work normally, so the car will stop in normal conditions. What you lose is ABS pulse braking during emergency stops, traction control, and stability control. Many drivers can manage a short drive to a garage. Don't drive long distances or in poor weather; emergency-stop performance without ABS is significantly worse, particularly at speed.
Should I get the module replaced or repaired? +
Repair through a specialist remanufacturer is usually the best option on older Mitsubishi cars, both for cost and because they have specific experience with these units. BBA Reman and ECU Testing in the UK both handle Mitsubishi ABS modules. New OEM modules are often discontinued or extremely expensive.
Could a low battery really cause this? +
Yes, more often than people realise. Modern ABS modules are sensitive to voltage; below 12.0V resting they sometimes throw codes that aren't really ABS faults. Charge or replace the battery first if it's old, and many intermittent C1000 codes clear on their own.
Manufacturer-specific notes
Some manufacturers publish additional definitions or variations for this code. Always cross-check with your vehicle's own service documentation.
Information only, not professional advice
The information on this page is provided for general guidance and educational purposes only. It is not a substitute for diagnosis or repair advice from a qualified mechanic. Always verify any fault before paying for repairs. carfaultcodes.co.uk accepts no liability for decisions made based on this information. Full terms →