ABS Valve Relay Circuit Short to Battery
What does C0122 mean?
The C0122 code means the vehicle's onboard diagnostic system has detected: ABS Valve Relay Circuit Short to Battery. This is a critical severity code.
Common Symptoms
- ABS warning light on
- ABS solenoid valves stuck open or energized
- Soft or spongy brake pedal
- Unusual brake behavior
- Traction control system disabled
Probable Causes (Ranked by Likelihood)
- ABS valve relay stuck in closed position Very High
- Short to battery voltage in relay wiring High
- Melted relay socket from overheating Moderate
- Chafed wire contacting a power source Moderate
- ABS module internal short on relay output Low
Step-by-Step Diagnostic Procedure
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Remove the ABS valve relay and check if the code clears
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Measure voltage at the relay control terminal -- should be 0V with relay removed
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If voltage is present with relay removed, trace wiring for a short to power
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Inspect relay socket for melting or heat damage
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Test ABS module relay driver circuit for internal short
Frequently Asked Questions
What happens when the ABS valve relay shorts to battery?
The solenoid valves receive constant power, which can cause them to stay energized. This may cause unpredictable brake modulation and a soft brake pedal because the valves are not being controlled properly by the ABS module.
Is a spongy pedal related to C0122?
Yes. When the ABS solenoid valves are constantly powered due to a relay short, they can hold brake fluid pathways open, reducing pedal firmness. This is a safety concern and should be repaired immediately.
Can I pull the relay to restore normal braking?
Yes, removing the ABS valve relay will disable the ABS system but should restore normal hydraulic braking. This is a safe temporary measure until the repair is completed.