Module, Electronic Steering Lock (ESL): Operation

The Electronic Steering Lock (ESL) module is designed to work in conjunction with the Body Control Module (BCM) to control a locking bolt that engages a machined slot in the steering shaft to prevent shaft rotation whenever a valid key is not present in the Ignition Node Module (IGNM) (without Passive Entry Keyless Go/PEKG), or when the status of the Keyless Ignition Node (KIN) transitions to OFF (with PEKG). The ESL can only be unlocked if the presence of a valid FOB with Integrated Key (FOBIK) unit is detected within the IGNM (without PEKG), or when the status of the KIN (with PEKG) transitions from OFF to any other status.

The electronic circuitry within the ESL contains all of the logic circuits and components to monitor and control the operation of the shaft locking bolt. The module uses the Controller Area Network (CAN) data bus for bi-directional communication with the BCM. If the ESL module detects a problem with the positioning or operation of the locking bolt, it sends an error message to the BCM. The BCM then sets and stores a Diagnostic Trouble Code (DTC) and sends an electronic error message over the CAN data bus to other electronic modules in the vehicle.

The ESL continuously monitors inputs from the BCM and the Antilock Brake System (ABS) module, then energizes the electric motor to move the locking bolt to the locked or unlocked position based upon those inputs. If the BCM receives an input from the Radio Frequency Hub (RFH) module indicating that an invalid FOBIK has been detected, the locking bolt remains in the locked position.

When the RFH module indicates that a valid FOBIK has been detected within the IGNM (without PEKG), or within the vehicle when the status of the KIN (with PEKG) transitions from OFF to any other status, the BCM has the ESL operate a motor to move the locking bolt to the unlocked position. However, to prevent inadvertent column locking due to a failure while the vehicle is being operated, the ESL module cannot move the locking bolt from the unlocked position to the locked position while a vehicle speed input indicates that the vehicle is still moving.

The hardwired circuits of the ESL may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the ESL or the electronic controls and communication between other modules and devices that provide some features of the SKIS. The most reliable, efficient and accurate means to diagnose the ESL or the electronic controls and communication related to SKIS operation requires the use of a diagnostic scan tool.