Multifunction Electronic Modules: Overview Ford Escape I facelift 2

Principles of Operation

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

Note. The time out for the battery saver relay and the accessory delay relay (both are controlled by the SJB) is 1 minute if the vehicle has less than 80 km (50 miles). Once the vehicle passes the approximate mileage threshold of 80 km (50 miles), the time out for both relays will be the normal 10 minute time out, as described by the Owner's Literature. For the battery saver relay, refer to INTERIOR LIGHTING. For the accessory delay relay, refer to GLASS, FRAMES AND MECHANISMS.

The SJB is a multifunction electronic 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

SJB CONTROL FUNCTIONS REFERENCE CHART

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

Some SJB parameters are programmable. Two types of programmable parameters are available: vehicle configuration and customer preference. Refer to MODULE CONFIGURATION for programmable parameters.

Field-Effect Transistor (FET) Protection

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

The circuit resets after a customer demand (ignition cycle) of the function (which switches the component on, causing the 30-minute battery saver timer to be energized). When an excessive circuit load (from a shorted circuit) 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 by the first failure does not clear by a command to clear the continuous DTCs.

The SJB does not allow the DTC to be cleared or the normal circuit function restored until a successful self-test (retrieving on-demand DTCs) proves that the fault has been repaired. After the self-test has successfully completed (no on-demand DTCs present), the continuous DTC clear and the normal circuit function returns.

The SJB has 3 predefined levels of short circuit tolerance established. When the first or second level is reached, the continuous DTC associated with the short circuit sets along with DTC B106E. These DTCs (B106E and the DTC associated with the shorted circuit) may be cleared using the Clear DTC operation on the scan tool as long as the fault itself has been corrected. Each and every time the scan tool retrieves DTCs from the module and a circuit is shorted, a level of short circuit tolerance is used up.

If any of the circuits are shorted past the third level (if DTCs have been retrieved 3 successive times with the short circuit not having been repaired), then DTCs B106F and B1342 are set along with the associated continuous DTC. These DTCs (B106F and B1342) cannot be cleared and the module must be replaced.

The initial short circuit must be successfully repaired and its associated DTC is cleared before the SJB is replaced or the new SJB may experience one or more of the short circuit tolerance levels being used up, causing a repeat replacement of the module.

The SJB FET protected output circuits for the handles, locks, latches and entry systems are the liftgate lock actuator circuit CPL10 (GN/WH) and the keypad illumination circuit CPK28 (WH/GN).

DTC B106E sets when the SJB has disabled a circuit due to a repetitive fault causing a circuit overload. A corresponding DTC for the circuit in question will also be set as follows

1. DTC B1034 - Radio Start Signal Circuit Failure
2. DTC B1218 - Horn Relay Coil Circuit Short to Vbatt
3. DTC B1304 - Accessory Delay Relay Coil Circuit Short To Battery
4. DTC B1316 - Battery Saver Relay Coil Circuit Short To Ground
5. DTC B1349 - Heated Backlight Relay Short To Battery
6. DTC B1474 - Battery Saver Power Relay Circuit Short To Battery
7. DTC B1502 - Lamp Turn Signal Left Circuit Short To Ground
8. DTC B1506 - Lamp Turn Signal Right Circuit Short To Ground
9. DTC B1626 - Lamp Keypad Output Short Circuit To Ground
10. DTC B2070 - Trailer Tow Relay Coil(s) Circuit Failure
11. DTC B2501 - LF Lamp Low Beam Circuit Failure
12. DTC B2503 - RF Lamp Low Beam Circuit Failure
13. DTC B2505 - LF Lamp High Beam Circuit Failure
14. DTC B2507 - RF Lamp High Beam Circuit Failure
15. DTC B2512 - Front Fog Lamp Relay CKT Short to Battery
16. DTC C1788 - Stoplamp Relay Output Circuit Short to Ground
17. DTC C1961 - Park Lamp Relay Coil Circuit Failure
18. DTC P0930 - Gear Shift Lock Solenoid Circuit Low

Normal Operation

When a repetitive fault causing a circuit overload is detected on certain output circuits, the Smart Junction Box (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. 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) - sets when the SJB has disabled a circuit due to a repetitive fault causing a circuit overload. For a complete list of corresponding DTCs, refer to the «PRINCIPLES OF OPERATION»(ref-344077-S08908484902009101600000).
2. DTC B106F (Module Disabled Due to External Fault) - sets when one or more output functions are permanently disabled due to a repetitive circuit overload fault. When DTC B106F is present (DTC B1342 may also be present), the SJB 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. 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 SBB02 (YE/RD).

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 SBB02 (YE/RD).

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 SBB02 (YE/RD).

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 SBB02 (YE/RD).

This pinpoint test is intended to diagnose the following

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

1. DTC U0155 (Lost Communication with Instrument Panel Cluster (IC) Control Module) - set by the Smart Junction Box (SJB) if data messages received from the Instrument Cluster (IC) over the Medium Speed Controller Area Network (MS-CAN) are missing for 5 minutes.

This pinpoint test is intended to diagnose the following

1. Module communication
2. IC

See also:
• SUPPLEMENTAL RESTRAINT SYSTEM