C1256
ABS Inlet Valve Coil RR Circuit Short To Battery
Chassis Chassis/Safety ABS Solenoid Circuit 🔴 Serious — Stop or limit driving
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What This Actually Means
In plain language — no jargon

The ABS system's rear-right inlet valve coil is receiving too much electrical power, like a light switch stuck in the ON position with excess voltage. This prevents the valve from functioning properly and disables ABS braking assistance.

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Symptoms You May Notice
3 known symptoms for this code
ABS warning light illuminated on dashboard
Loss of anti-lock braking function on rear wheels
Possible extended stopping distance or wheel lockup during hard braking
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ECU monitors the coil circuit voltage and current draw of the RR inlet valve. It expects a controlled voltage pulse to energize the solenoid; a short to battery means the coil receives sustained maximum voltage instead of the proper modulated signal. The ECU detects this abnormal high voltage condition and triggers the fault code.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Coil Circuit Voltage 0–5V modulated control signal Sustained 12–14V (battery voltage)
Coil Current Draw 0.5–2.0 A during pulse >2.5 A sustained or circuit stuck high
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
ABS wiring harness connector (RR wheel)
Inspect and reseat the connector at the rear-right ABS inlet valve to eliminate loose contact causing the short.
2
ABS inlet valve coil (RR)
Replace the faulty solenoid coil if it has shorted internally to battery voltage.
3
ABS control module wiring and fuse
Check for damaged or pinched wiring between the ABS module and RR valve; repair or replace compromised sections.