Body Control Systems: Description and Operation

Module Controlled Functions

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

There are 2 multifunction electronic control modules consisting of the following:

- Driver Seat Module (DSM)
- SJB

Driver Seat Module (DSM)

The Driver Seat Module (DSM) is located under the driver seat. It controls the memory functions of the seat positions, the adjustable pedals, and the exterior rear view mirrors. The memory driver seat feature allows the driver to program a personalized seat position that can be recalled using the memory set switches or the Remote Keyless Entry (RKE) transmitter(s). Refer to Seats.

Smart Junction Box (SJB)

NOTE: The time out for the battery saver relay and the accessory delay relay (both are controlled by the SJB) is one 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 is 10 minutes, as described by the Owner's Literature. For the battery saver relay, refer to Courtesy Lamp. For the accessory delay relay, refer to Windows. Testing and Inspection

The SJB (located under the passenger side kick panel) controls and provides diagnostic information for the following:

- Autolamps
- Battery saver function
- Delayed accessory relay function
- Exterior lighting
- Horn
- Interior lighting
- Power door locks
- RKE system/keyless entry keypad
- Tire Pressure Monitoring System (TPMS)

Post Crash Alert

A new function controlled by the SJB is the post crash alert. If the Restraints Control Module (RCM) determines an impact of severity enough to deploy air bags has occurred (the air bags may or may not be deployed by the RCM), the RCM will send a message to the Instrument Cluster (IC) over the High Speed Controller Area Network (HS-CAN). The IC sends the message to the SJB over the Medium Speed Controller Area Network (MS-CAN) and the SJB will activate the post crash alert function. The post-crash alert function cycles the horn on 3 times, then off for 4 seconds, then on 3 times, etc., in this cycle until the battery dies or the function is turned off. The hazard lights will also flash with the horn sounding, but will keep flashing during the horn off cycle.

The post crash alert function can be turned off by:

- pressing the hazard switch (which may need to be pressed more than once).
- pressing the RKE transmitter UNLOCK button.
- pressing the RKE transmitter PANIC button.

This feature acts similar to the perimeter alarm, but the horn cycle is different. The perimeter alarm function cycles the horn on and off, in regular intervals until 2 minutes and 45 seconds have elapsed, the battery dies or the function is turned off. Turning the ignition to the ON position will not deactivate this function, but will deactivate an activated perimeter alarm.

The post crash alert function cannot be configured off.

Upfitter System

The upfitter system contains:

- 4 blunt cut relay controlled voltage circuits
- 4 upfitter relays
- Upfitter relay box
- Upfitter switch assembly

The upfitter switches are located in the instrument panel center finish panel under the climate control assembly. The upfitter switches have individually lighted indicators that illuminate when the switch is in the ON position (the indicator lights for the individual upfitter switches are not controlled by the headlamp switch). The backlighting for the upfitter switches is adjustable and is controlled by the dimmer switch.

The upfitter system switches are used to control relays which switch high-current loads. The upfitter switches are not designed to carry any significant loads. They are designed to allow the driver to manually close the relay coil circuit and provide power to added options. The upfitter relays are located above the glove box. The output circuits of the upfitter relays go to the interior of the vehicle and are blunt cut. The blunt cut ends are located on the driver side next to the parking brake bracket, and are accessed through the opening in the instrument panel when the instrument panel steering column cover is removed.

The 4 upfitter system switches control:

- 1 fused (10A), voltage at all times, relay.
- 1 fused (15A), voltage at all times, relay.
- 2 fused (30A), voltage at all times, relays.