DTC C0227: Left Front Wheel Speed Sensor Signal Erratic: Diagnosis

WARNING: This page does not describe the selected car, but rather 54 other vehicles, including the 1999 Oldsmobile Bravada, 1999 GMC Yukon, 1999 GMC Suburban, 1999 GMC Sonoma, and 1999 GMC Savana Special. However, it is still accessible from the selected car via links, so may be relevant.

Perform diagnostic system check. See DIAGNOSTIC SYSTEM CHECK. After performing diagnostic system check, go to next step.
Turn ignition off. Disconnect 4-pin EBCM harness connector and inspect for signs of corrosion or damage. Inspect wheel speed sensor, sensor cable and connectors for signs of damage or corrosion. If connections are okay, go to next step. If connections are damaged or corroded, go to step 6) .
Using DVOM, check resistance between 4-pin EBCM harness connector terminals "A" and "D". Wiggle harness in various locations while monitoring DVOM reading. See WSS TEMPERATURE-VS-SENSOR RESISTANCE table. If resistance is as specified and does not fluctuate, go to step 5) . If not, go to next step.
Disconnect wheel speed sensor harness connector. Check resistance between wheel sensor terminals "A" and "B". See WSS TEMPERATURE-VS-SENSOR RESISTANCE table. If resistance is as specified, go to step 7) . If not, go to step 8) .
Reconnect all harness connectors. Remove left front tire, hub and rotor. Verify right front wheel speed sensor is securely mounted and tone wheel is in good condition. If damage is not found, go to step 9) . If damage is found, go to step 10) .
Make necessary repairs.
Repair open, short or high resistance between wheel speed sensor circuits.
Replace wheel speed sensor.
Malfunction is intermittent. Inspect all connectors and harnesses for damage which may result in high resistance when all components are connected. See DIAGNOSTIC AIDS .
Make necessary repairs.