Hyundai Elantra – Check Engine Light and EPS Light – C1201 Wheel Speed Sensor LH Range/Performance
Hyundai Elantra 2011 with ABS/ESP and EPS.
Symptom and diagnosis.
2011-2013 Hyundai Elantra’s came out with electric power steering and ESP abs with electronic stability control units. both of which are hard to find the information for,
the fault code came in with the check engine light on the EPS light on and no abs light on, the power steering was heavier than normal, which is why the vehicle came in the first place.
The vehicle was scanned and revealed that all the sensors where not showing live data. with the fault codes;
C1201 – Wheel speed sensor ,front left component faulty, present as history and present faults.
C1202 – Wheel speed sensor, front left , air gap too wide.
C1204 – Wheel speed sensor, front right, component faulty.
C1207 – Wheel speed sensor, rear left, component faulty.
C1207 – Wheel speed sensor, rear right, component faulty.
EPS – electric power steering faults
C1622 – Vehicle Speed CAN message, signal invalid
Engine Control Unit faults.
P2159 – Driving Speed sensor B, outside specified Range. stored and sporadic
It was time to raise the vehicle and check the abs sensors, the abs sensors looked ok, and as a standard practice a scope trace was produced the sensor output was a digital type, and the voltage was from 0 volts to 1.7 volts, cool the sensors works, but not correctly.
next was to find that the signal was getting to the abs unit, traced the colour wires to the harness plug and they where present. maybe shorted or the step up resistor blown,
But still no live data.
The speedo on the instrument cluster worked so there must be an issue with the scan tool, or ABS module, the fuses checked all 3 of the fuses. by looking at the wiring diagram it was noted that the ABS and ESP where separate layers inside the same unit.
So the signal comes from the wheel speed sensor to the ABS ECU the ABS ECU sends out a signals to the ESP unit for wheel speed, Then the Processed signal from the ESP unit sends out the signal through another wire to the engine ECU for further processing. the multiple layers of processing is what was strange in fact this wasnt happening,
diagrams are to help illustrate what and why the ABS/ESP unit was faulty,
a new unit was installed into the vehicle and programming was carried out as the unit does not know the vehicle options that it has when purchased.
Steering angle calibrated and yaw and lateral sensors zero point calibrated.
Live data checked that the wheel speed sensors signal speeds where coming through to the scan tool which meant we had full communications of Stability control to Engine ECU.
The vehicle was then test driven, checking the abs pump motor and actuation was correct and that the esp light would come on when out of control. (this part was hard to achieve)
the vehicle then given back to the client, knowing that the repairs are correct and tested,
knowing that there was not any warning light for the abs and traction control lead us to believe the unit was faulty, and continue testing