Handles, Locks, Latches and Entry Systems - Without Intelligent Access (IA)

Handles, Locks, Latches and Entry Systems - Without Intelligent Access (IA)

Principles of Operation

NOTE: The Smart Junction Box (SJB) is also known as the Generic Electronic Module (GEM).

The SJB (Smart Junction Box) receives inputs and delivers outputs to many of the electronically controlled features of the vehicle. The SJB (Smart Junction Box) constantly monitors the system under its control and reports an issue in the form of a DTC.

Power Door Locks Without Memory

Regardless of the key position, the SJB (Smart Junction Box) is supplied voltage at all times. When the SJB (Smart Junction Box) receives a signal from the Remote Keyless Entry (RKE) transmitter, the keyless entry keypad, or the door lock control switches, the SJB (Smart Junction Box) supplies a ground signal to the appropriate lock or unlock relay. The ground signal closes the relay which supplies voltage to the door lock actuators. The door lock actuators then actuate to a lock or unlock position.

Power Door Locks With Memory

The SJB (Smart Junction Box) controls all of the passenger door lock actuators and receives input from the passenger door lock control switch. The Driver Door Module (DDM) controls only the driver door lock actuator and receives input from the driver door lock control switch. The 2 modules communicate the lock or unlock commands through the Medium Speed Controller Area Network (MS-CAN).

The SJB (Smart Junction Box) and the DDM (Driver Door Module) are supplied voltage at all times. When the SJB (Smart Junction Box) receives a signal from the Remote Keyless Entry (RKE) transmitter, the keyless entry keypad, or the RH door lock control switch, the SJB (Smart Junction Box) sends a command to the DDM (Driver Door Module) through the MS-CAN (Medium Speed Controller Area Network), and a ground signal to the lock and unlock relays. When the LH door lock control switch is pressed, the DDM (Driver Door Module) receives the lock or unlock signal. The DDM (Driver Door Module) sends a request through the MS-CAN (Medium Speed Controller Area Network) to the SJB (Smart Junction Box) to lock or unlock the passenger doors. The SJB (Smart Junction Box) then responds to the DDM (Driver Door Module) request, authorizing a lock or unlock of the driver door by the DDM (Driver Door Module). The DDM (Driver Door Module) then supplies voltage and ground to the driver door lock actuator based on the lock or unlock request. The ground signal in the SJB (Smart Junction Box) closes the relay which supplies voltage to the remaining door lock actuators. The remaining door lock actuators then actuate to a lock or unlock position determined by the relay.

Luggage Compartment Lid Release

NOTE: When using the Integrated Keyhead Transmitter (IKT), 2 presses of the luggage compartment lid release button (within 3 seconds) are required to release the luggage compartment lid.

The luggage compartment lid release system is inhibited when the vehicle speed exceeds 8 km/h (5 mph). The luggage compartment lid latch releases the luggage compartment lid when the customer requests it opened using either the IKT (Integrated Keyhead Transmitter), the keyless entry keypad, or the luggage compartment lid release switch. When the SJB (Smart Junction Box) receives a signal to release the luggage compartment lid, the SJB (Smart Junction Box) supplies voltage to the luggage compartment lid latch. The luggage compartment lid latch then actuates to release the luggage compartment lid.

Remote Keyless Entry (RKE)

The SJB (Smart Junction Box) interprets radio frequency signals from the Remote Keyless Entry (RKE) transmitters. The SJB (Smart Junction Box) requests the illuminated entry feature to turn the interior lamps on when an unlock command is received. If a lock command is received, the illuminated entry feature turns off.

The RKE (Remote Keyless Entry) transmitter supplies a signal to the SJB (Smart Junction Box) when any button is touched. The SJB (Smart Junction Box) then supplies voltage to the appropriate door lock actuator(s) to lock or unlock the doors. The RKE (Remote Keyless Entry) transmitter can also be used to release the luggage compartment lid or activate the panic alarm. On vehicles with memory, the RKE (Remote Keyless Entry) transmitter also causes the SJB (Smart Junction Box) to send an MS-CAN (Medium Speed Controller Area Network) message to the Driver Seat Module (DSM) to activate all memory features to the positions associated with the RKE (Remote Keyless Entry) transmitter being used.

Keyless Entry Keypad

The keyless entry keypad is hardwired to the SJB (Smart Junction Box). The SJB (Smart Junction Box) interprets the inputs from the keyless entry keypad and then controls the associated operation. The keyless entry keypad is illuminated for 5 seconds when any button is touched and also anytime that the courtesy lighting is on. The SJB (Smart Junction Box) requests the illuminated entry feature to turn the interior lamps on when a valid entry code is received. If a lock all doors code is entered, the illuminated entry feature turns off.

NOTE: The keyless entry keypad does not lock the doors if the driver door is ajar.

The keyless entry keypad supplies a signal to the SJB (Smart Junction Box) when the buttons are pressed. The SJB (Smart Junction Box) then supplies voltage to the appropriate door lock actuator(s) to lock or unlock the doors. The keyless entry keypad can also be used to release the luggage compartment lid. On vehicles with memory, the keyless entry keypad also causes the SJB (Smart Junction Box) to send an MS-CAN (Medium Speed Controller Area Network) message to the Driver Seat Module (DSM) to activate all memory features to the positions associated with the personal entry code entered on the keypad.

Field-Effect Transistor (FET) Protection

Field-Effect Transistor (FET) is a type of transistor that when used with module software can be used to monitor and control current flow on module outputs. The FET (Field-Effect Transistor) protection strategy is used to prevent module damage in the event of excessive current flow.

The SJB (Smart Junction Box) utilizes a FET (Field-Effect Transistor) protective circuit strategy for many of its outputs (for example, a headlamp output circuit). Output loads (current level) are monitored for excessive current (typically short circuits) and are shut down (turns off the voltage or ground provided by the module) when a fault event is detected. A continuous DTC is stored at the fault event and a cumulative counter is started.

When the demand for the output is no longer present, the module resets the FET (Field-Effect Transistor) circuit protection to allow the circuit to function. The next time the driver requests a circuit to activate that has been shut down by a previous short (FET (Field-Effect Transistor) protection) and the circuit remains shorted, the FET (Field-Effect Transistor) protection shuts off the circuit again and the cumulative counter advances.

When the excessive circuit load occurs often enough, the module shuts down the output until a repair procedure is carried out. Each FET (Field-Effect Transistor) protected circuit has 3 predefined levels of short circuit tolerance based on the harmful effect of each circuit fault on the FET (Field-Effect Transistor) and the ability of the FET (Field-Effect Transistor) to withstand it. A module lifetime level of fault events is established based upon the durability of the FET (Field-Effect Transistor). If the total tolerance level is determined to be 600 fault events, the 3 predefined levels would be 200, 400 and 600 fault events.

When each tolerance level is reached, the continuous DTC that was stored on the first failure cannot be cleared by a command to clear the continuous DTCs. The module does not allow this code to be cleared or the circuit restored to normal operation until a successful self-test proves that the fault has been repaired. After the self-test has successfully completed (no on-demand DTCs present), DTC B106E and the associated continuous DTC (the DTC related to the shorted circuit) automatically clears and the circuit function returns.

When the first or second level is reached, the continuous DTC (associated with the short circuit) sets along with DTC B106E. These DTCs can be cleared using the module on-demand self-test, then the Clear DTC operation on the scan tool (if the on-demand test shows the fault corrected). The module never resets the fault event counter to zero and continues to advance the fault event counter as short circuit fault events occur.

If the number of short circuit fault events reach the third level, then DTCs B106F and B1342 set along with the associated continuous DTC. These DTCs cannot be cleared and the module must be replaced.

The only SJB (Smart Junction Box) FET (Field-Effect Transistor) protected output circuit for the handles, locks, latches and entry systems is the keypad illumination circuit CPK28 (WH/GN).