Q: Vehicle has dtc c100a

Your next step is to disconnect the anti lock brake module and jack up the left front wheel. While testing with a multi-meter on A/C volts check between pins 12 and 13. They are DG/LG and DG/TN wires. Spin the wheel while testing the wires and you should start to generate a voltage signal from the left front sensor. If you are not getting voltage then the problem is in the wiring or connection between the module and the left front sensor.

Pay special attention to the connections at the sensor and module for any loose or corroded connections. If you do get a voltage from the sensor then you either have a defective module or power and ground to the module is bad. If you need help with this, a mechanic can come diagnose your Check Engine Light trouble code and accurately fix what’s necessary.