Multifunction Electronic Modules: Overview Ford Ranger II facelift

Principles of Operation

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

The SJB is a multifunction module that controls many of the vehicle systems. Several SJB functions utilize hardwired inputs and/or outputs. The SJB controls the following hardwired functions, using the corresponding inputs and outputs.

OPERATION CHART

In addition, the SJB is involved in other vehicle systems through communication over the Medium Speed Controller Area Network (MS-CAN). For a detailed list of SJB network inputs and outputs, refer to Principles of Operation in MODULE COMMUNICATIONS NETWORK.

Some SJB parameters are programmable. Two types of programmable parameters are available: vehicle configuration and programmable parameter. For information on programmable parameters, refer to MODULE CONFIGURATION.

The SJB utilizes a protective circuit strategy for many of its outputs (for example, the headlamp output circuit). Output loads are monitored by the SJB for excessive current (typically short circuits) and are shut down (voltage or ground provided by the module are turned off) when a fault is detected. A continuous DTC is stored at that time for the fault. The circuit then resets after an ignition cycle or customer demand of the function (switching the component on, 30-minute battery saver being energized).

When an excessive circuit load occurs several times, the module shuts down the output until a repair procedure is carried out. At the same time, the continuous DTC that was stored on the first failure does not clear by a command to clear the continuous DTCs. The module does not allow this DTC to be cleared or the circuit restored to normal until a successful on-demand self-test proves that the fault has been repaired. After the on-demand self-test has successfully completed (no on-demand DTCs present), the continuous DTC has cleared and the circuit function returns.

Normal Operation

The Smart Junction Box (SJB) controls the output of the Daytime Running Lamps (DRL), fog lamps, one-touch down driver power window, accessory delay relay, windshield wiper park/run, windshield wiper speed, and windshield washer. When a repetitive fault causing a circuit overload is detected on any of the output circuits, the SJB disables the circuit by removing voltage or ground, to the affected circuit. The circuit remains disabled until the fault is corrected and an on-demand self-test is run. After the on-demand self-test has been run, any DTCs related to the fault are cleared.

1. DTC B106E (Solid State Driver Disabled Due to Short Circuit) - a continuous memory and on-demand DTC that sets when the SJB has temporarily disabled a circuit due to a repetitive fault causing a circuit overload. A corresponding DTC for the circuit in question also sets as follows: DTC B106F (Module Disabled Due to External Fault) - a continuous memory and on-demand DTC that sets when one or more output functions are permanently disabled due to a repetitive circuit overload fault. DTC B106F sets with DTC B106E. When DTC B106F is present, the SJB must be replaced after the fault condition has been corrected. DTC B1304 (Accessory Delay Relay Coil Circuit Short to Battery) - Accessory delay relay circuit short to battery voltage DTC B2512 (Front Fog Lamp Relay Ckt Short to Battery) - Fog lamp relay circuit short to battery voltage DTC B2973 (Daytime Running Lamp Output Shorted to Ground) - DRL output short to ground

This pinpoint test is intended to diagnose the following

1. Output circuit short to ground or voltage
2. SJB

The Smart Junction Box (SJB) monitors the voltage from the battery to determine if it is above or below specific thresholds and sets DTC B1317 in continuous memory if the SJB detects high battery voltage above 15 volts on circuit SBB01.

1. DTC B1317 (Battery Voltage High) - a continuous memory DTC that sets when the SJB detects battery voltage above 15 volts on circuit SBB01.

This pinpoint test is intended to diagnose the following

1. Charging system concern
2. SJB

The Smart Junction Box (SJB) monitors the voltage from the battery to determine if it is above or below specific thresholds and sets DTC B1318 in continuous memory if the SJB detects low battery voltage below 10 volts on circuit SBB01.

1. DTC B1318 (Battery Voltage Low) - a continuous memory DTC that sets when the SJB detects battery voltage below 10 volts on circuit SBB01.

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. High circuit resistance
3. SJB

The Smart Junction Box (SJB) and the PCM communicate using the High Speed Controller Area Network (HS-CAN) between the Instrument Cluster (IC) and the Medium Speed Controller Area Network (MS-CAN) between the IC and the PCM. Messages are exchanged between the modules on the 2 networks for the purposes of determining what functions are being carried out.

1. DTC U0100 (Lost Communication With ECM /PCM) - set by the SJB if the ignition is in RUN, the SJB supply voltage is greater than 10.5 volts, less than 15 volts and if the engine RPM, vehicle speed or throttle position messages are missing.

This pinpoint test is intended to diagnose the following

1. Module communication
2. SJB
3. PCM

The Smart Junction Box (SJB) and the Instrument Cluster (IC) communicate using the Medium Speed Controller Area Network (MS-CAN). Messages are exchanged between the modules on the MS-CAN for the purposes of determining what functions are being carried out.

1. DTC U0155 (Lost Communication with Instrument Panel Cluster ( IC ) Control Module) - set by the SJB if ignition status message is present, the SJB supply voltage is greater than 10.5 volts, the ignition must be in the ON position for a minimum of 5 seconds and if messages are missing for 15 seconds or longer from the IC over the MS-CAN .

This pinpoint test is intended to diagnose the following

1. Module communication
2. SJB
3. IC

See also:
• AUTOMATIC TRANSAXLE/TRANSMISSION - 5R44E AND 5R55E