C1228
Speed Wheel Sensor LR Input Short Circuit To Ground
Chassis Chassis/Safety ABS Wheel Speed Sensor 🔴 Serious — Stop or limit driving
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What This Actually Means
In plain language — no jargon

The left rear wheel speed sensor is sending a constant ground signal instead of the normal pulsing signal it should send. It's like a light switch that's stuck in the 'off' position instead of flickering on and off.

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Symptoms You May Notice
3 known symptoms for this code
ABS warning light illuminated on dashboard
Traction control or stability control disabled
ABS system inoperative or reduced braking performance
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ECM monitors the left rear wheel speed sensor for alternating voltage signals as the wheel rotates. A short to ground causes the sensor voltage to drop to zero and remain there, preventing the ECM from detecting wheel speed changes. The ECM detects this abnormal constant low voltage condition and sets the fault code.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Sensor Voltage Signal Alternating AC signal 0.5-2.0V peak Constant 0V or unable to detect pulse pattern
Signal Resistance 800-1600 ohms at sensor coil Less than 100 ohms (short to ground)
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
Wheel speed sensor wiring harness
Inspect the sensor connector and wiring for corrosion, water damage, or loose pins and repair or reseat connections.
2
Left rear wheel speed sensor
Replace the sensor if wiring checks out; sensor internal short is most common failure mode.
3
ABS module or ECM reprogramming
Clear the fault code after repairs and test drive to confirm sensor signal returns to normal.