Multifunction Electronic Modules: Overview Ford Flex I

Principles of Operation

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

The SJB controls various systems (such as exterior lighting, interior lighting, power door locks, anti-theft system, dimmable backlighting and the battery saver feature) by monitoring inputs from switches, sensors and messages sent from other modules on the Medium Speed Controller Area Network (MS-CAN). Based on the inputs received, the SJB activates outputs. For example, the SJB monitors the headlamp switch position. Based on this input, the SJB may provide voltage to the exterior lamps.

Field-Effect Transistor (FET) Protection

A 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 protection strategy is used to prevent module damage in the event of excessive current flow.

The SJB utilizes an FET 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 short circuit 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 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 protection) and the circuit is still shorted, the FET 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 protected circuit has 3 predefined levels of short circuit tolerance based on the harmful effect of each circuit fault on the FET and the ability of the FET to withstand it. A module lifetime level of fault events is established based upon the durability of the FET. 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 short circuit 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 DTC (the DTC related to the shorted circuit) automatically clears and the circuit function returns.

When each level is reached, the 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 short circuit DTC. DTC B106F cannot be cleared and the module must be replaced after the repair.

Normal Operation

The Smart Junction Box (SJB) controls the output of several vehicle systems by means of solid state drivers. A DTC sets when an overload occurs on any of these drivers. The module also tracks the number of repetitive faults on each of these circuits, and then it compares said number of overloads to 3 progressive thresholds established for each circuit. If the third threshold hase not been met, the DTC for the affected circuit can be cleared by eliminating the fault, clearing the DTCs and then running a self-test.

At the point that each of the first 2 thresholds is met, DTC B106E sets along with a DTC related to the affected circuit. Once the final (third) threshold has been met, the affected output is permanently disabled, and DTC B106F sets, at which time the SJB must be replaced.

1. DTC B106E (Solid State Driver Disabled Due to Short Circuit) - a continuous DTC that sets when the SJB has disabled an output circuit due to a repetitive fault that overloads said circuit. A corresponding DTC for the circuit in question is also set.
2. DTC B106F (Module Disabled Due to External Fault) - a continuous DTC that sets when the SJB has permanently disabled one or more output functions due to a repetitive circuit overload. DTC B1342 also sets at this time.

When DTC B1342 is set because the module has reached a third threshold and the SJB has permanently disabled an output, no DTCs can be cleared from the SJB . Using the module self-test to confirm a repair is not possible and a measurement using a digital multimeter of the affected output circuit is required to make sure the fault condition no longer exists.

This pinpoint test is intended to diagnose the following

1. Output circuit short
2. SJB

The Smart Junction Box (SJB) monitors the voltage from the battery to determine if it goes above or below specific thresholds and sets DTC B1317 in continuous memory and on-demand if the SJB detects high battery voltage above 15.5 volts on circuit SBB01.

1. DTC B1317 (Battery Voltage High) - a continuous memory or on-demand DTC that sets when the SJB detects battery voltage above 15.5 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 goes above or below specific thresholds and sets DTC B1318 in continuous memory and on-demand if the SJB detects low battery voltage below 10 volts on circuit SBB01.

1. DTC B1318 (Battery Voltage Low) - a continuous memory or on-demand 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 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. IC
3. SJB

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

The Driver Seat Module (DSM) allows the driver to program a personalized seat position that can be recalled using the memory switch or a Remote Keyless Entry (RKE) transmitter (part of the key). In addition to the position of the driver seat, the DSM also controls the position of the exterior mirrors and the adjustable pedals. Refer to SEATING .

The DSM is part of the Medium Speed Controller Area Network (MS-CAN), over which it receives the selected transmission gear message. All other functions of the DSM are hardwired.

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 protection strategy is used to prevent module damage in the event of excessive current flow.

The SJB utilizes an FET 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 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 protection) and the circuit remains shorted, the FET 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 protected circuit has 3 predefined levels of short circuit tolerance based on the harmful effect of each circuit fault on the FET and the ability of the FET to withstand it. A module lifetime level of fault events is established based upon the durability of the FET. 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.

When a repetitive fault causing a circuit overload is detected on certain output circuits, the Driver Seat Module (DSM) 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. When the on-demand self-test has been run after all faults have been corrected, any DTCs related to the fault are cleared.

1. DTC B106E (Solid State Driver Disabled Due to Short Circuit) - a continuous DTC that sets when the DSM has disabled a circuit due to a repetitive fault causing a circuit overload.
2. DTC B106F (Module Disabled Due to External Fault) - a continuous DTC that sets when one or more output functions are permanently disabled due to a repetitive circuit overload fault. DTC B106F is set with DTC B106E. When DTC B106F is present, the DSM must be replaced after the fault condition has been corrected.

This pinpoint test is intended to diagnose the following

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

The Driver Seat Module (DSM) monitors the voltage from the battery to determine if it goes above or below specific thresholds and sets DTC B1317 in continuous memory if the Smart Junction Box (SJB) detects high battery voltage above 15 volts on circuit SBP03.

1. DTC B1317 (Battery Voltage High) - a continuous memory DTC that sets when the DSM detects battery voltage above 15 volts on circuit SBP03.

This pinpoint test is intended to diagnose the following

1. Charging system concern
2. DSM

The Driver Seat Module (DSM) monitors the voltage from the battery to determine if it goes above or below specific thresholds and sets DTC B1318 in continuous memory if the DSM detects low battery voltage below 10 volts on circuit SBP03.

1. DTC B1318 (Battery Voltage Low) - a continuous memory DTC that sets when the DSM detects battery voltage below 10 volts on circuit SBP03.

This pinpoint test is intended to diagnose the following

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

The Driver Seat Module (DSM) and the Smart Junction Box (SJB) 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 U0140 (Lost Communication With Body Control Module (GEM)) - set by the DSM whenever it has lost communication to the SJB for 15 seconds or longer as long as the module voltage is between 10 and 15 volts.

This pinpoint test is intended to diagnose the following

1. Module communication
2. DSM
3. SJB

The Driver Seat Module (DSM) 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 DSM if ignition status message is present, the DSM 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. DSM
3. IC