Multifunction Electronic Modules System: Other Mercury Montego III

Module Controlled Functions

The vehicle is equipped with a smart junction box (SJB) and a driver seat module.

Smart Junction Box (SJB)

The SJB is a combined fuse panel and microprocessor that controls the following systems

1. interior lighting
2. exterior lighting
3. horn
4. heated rear window
5. delayed accessory
6. power door locks (including SMART, autolocking and luggage compartment lid release)
7. remote keyless entry (RKE)
8. perimeter anti-theft
9. battery saver relay

Driver Seat Module (DSM)

The DSM controls the user selected comfort functions. These functions are memory seat, memory mirrors and memory pedals. Up to 2 personal settings can be programmed into the DSM memory and when selected the DSM returns the user adjustable features to the programmed positions.

Refer to SYSTEM WIRING DIAGRAMS (Montego), SYSTEM WIRING DIAGRAMS (Five Hundred), SYSTEM WIRING DIAGRAMS (Freestyle) for schematic and connector information.

The SJB constantly monitors its subsystems for concerns. If a concern is found in one of the subsystems, the SJB records the concern in the form of a diagnostic trouble code (DTC).

The ignition switch position is very important to the SJB functionality. Erratic or unexpected SJB functions can often be traced to problems with these ignition SJB inputs.

The SJB controls a variety of systems

1. battery saver relay
2. heated rear window
3. interior lighting
4. exterior lighting
5. remote keyless entry (RKE)
6. delayed accessory
7. power door locks (including SMART, autolocking and luggage compartment lid release)
8. perimeter anti-theft
9. horn

Possible Causes

1. circuit 905 (GY/LB) open
2. circuit 906 (RD/OG) open
3. circuit 1231 (RD/WH) open
4. circuit 1203 (BK/LB) open
5. circuit 1205 (BK) open
6. SJB

Scheme 46

Scheme 47

1. A1 CHECK THE SJB VOLTAGE SUPPLY CIRCUITS FOR AN OPEN Key in OFF position. Disconnect: SJB C2280a. Disconnect: SJB C2280g. Using the following table, measure the voltage between the SJB, harness side and ground: SJB CONNECTOR-PIN REFERENCE SJB Connector-pin Circuit C2280a-29 1231 (RD/WH) C2280g-l 906 (RD/OG) C2280g-2 905 (GY/LB) Are the voltages greater than 10 volts? Yes : GO to A2. No : REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test.
2. A2 CHECK THE SJB GROUND CIRCUIT FOR AN OPEN Connect: SJB C2280g. Disconnect: SJB C2280e. Measure the resistance between the SJB C2280a-30, circuit 1203 (BK/LB), harness side and ground; and between the SJB C2280e-3, circuit 1205 (BK), harness side and ground. Are the resistances less than 5 ohms? Yes : REFER to «MODULE COMMUNICATIONS NETWORK»(ref-233024) to continue communication diagnosis. No : REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test.

Refer to SYSTEM WIRING DIAGRAMS (Montego), SYSTEM WIRING DIAGRAMS (Five Hundred), or SYSTEM WIRING DIAGRAMS (Freestyle) for schematic and connector information.

Drivers Seat Module (DSM)

The DSM allows automatic positioning of the memory driver seat 2 programmable positions. For additional information, refer to SEATING .

1. circuit 1205 (BK) open
2. circuit 566 (DG) open
3. circuit 1203 (BK/LB) open
4. circuit 956 (OG/LG) open

Scheme 48

Scheme 49

1. B1 CHECK THE DSM VOLTAGE SUPPLY CIRCUITS FOR AN OPEN Key in OFF position. Disconnect: DSM C341a. Disconnect: DSM C341c. Measure the voltage between the DSM C341a-2, circuit 566 (DG), harness side and ground; and between the DSM C341c-1, circuit 956 (OG/LG), harness side and ground. Are the voltages greater than 10 volts? Yes : GO to B2. No : REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test.
2. B2 CHECK THE DSM GROUND CIRCUIT FOR AN OPEN Measure the resistance between the DSM C341a-1, circuit 1205 (BK), harness side and ground; and between the DSM C341c-13, circuit 1203 (BK/LB), harness side and ground. Are the resistances less than 5 ohms? Yes : REFER to «MODULE COMMUNICATIONS NETWORK»(ref-233024) to continue communication diagnosis. No : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.

Scheme 50