C1266
ABS Valve Power Relay Circuit Failure
Chassis Chassis/Safety ABS system 🔴 Serious — Stop or limit driving
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What This Actually Means
In plain language — no jargon

The ABS system's power relay—which supplies electricity to the ABS control valve—has failed or lost its electrical connection, like a light switch that won't turn on. Without this relay working, the ABS pump cannot function and anti-lock braking is disabled.

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Symptoms You May Notice
3 known symptoms for this code
ABS warning light illuminated on dashboard
ABS system inoperative; brakes lock up under hard braking
Loss of anti-lock braking functionality
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ABS module monitors the voltage and continuity of the ABS valve power relay circuit. It sends a control signal to activate the relay and measures the response voltage at the relay coil and switch contacts. If the relay fails to energize or the circuit shows open/short conditions, the fault is logged.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Relay coil voltage 11.5–14.5V when energized Below 10V or no voltage detected
Relay switch continuity Less than 1 ohm resistance when closed Open circuit or resistance above 5 ohms
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
ABS relay connector
Inspect and reseat the relay connector in the ABS module or fuse box; clean corrosion from pins with a wire brush.
2
ABS power relay
Locate the relay in the fuse box or ABS module and swap it with an identical relay from another circuit to test; replace if faulty.
3
ABS valve power wiring harness
Inspect wiring from the relay to the ABS valve for cuts, corrosion, or loose connections and repair or replace damaged sections.