Grand Cherokee 4WD V8-5.2L VIN Y (1998)
VEHICLE THEFT SECURITY SYSTEM
The vehicle theft security system (VTSS) monitors the vehicle doors, ignition switch, power door locks and the door key cylinder switches to
determine if the alarm should be sounded and the engine prevented from starting. When an unauthorized entry is detected, the system responds by
sounding the horn, flashing the headlamps and flashing the tail and park lamps for three minutes. The body control module also sends a message to
the powertrain control module that it is not OK to start.
The system can be armed by using the Remote Keyless Entry (RKE) transmitter to lock the doors or by opening the door, pressing the power door
lock switch and exiting the vehicle. The system uses a security lamp located above the instrument cluster to indicate when the system is armed.
VTSS can be disarmed by unlocking either front door, liftgate or with the RKE transmitter. If the vehicle has been tampered with, the indicator
will change from a slow steady flash to a quick double flash and the horn chirp will be inhibited when a lock command from the RKE transmitter
is received.
Panic alert flashes the head and tail lamps, pulses the horn and disarms the alarm. The driver can exit panic mode by either pushing the panic
button again on the RKE transmitter or driving the vehicle above 15 MPH.
NOTE: Whenever a body control module is replaced, the VTSS must be enabled by unlocking the doors with the key one time (which allows the
BCM to see that the vehicle is equipped with VTSS) and enabling the system using the DRB.
Trouble Codes
BUS FAILURE MESSAGES
Short to Battery - Either or both of the bus wires are shorted to the battery potential.
Short to 5 Volts - Either or both of the bus wires are shorted to a 5-volt potential.
Short to Ground - Either or both of the bus wires are shorted to ground.
Bus (+) & Bus (-) Shorted Together - The two bus wires are shorted together.
No Termination - The bus system has lost connection with all of its terminators.
Bus Bias Level Too Low - Either or both of the bus wire potentials are significantly below their normal 2.5 volts.
Bus Bias Level Too High - Either or both of the bus wire potentials are significantly above their normal 2.5 volts.
No Bus Bias - The bus system has lost connection with all modules that provide bias. Bus (+) Open - The bus (+) wire has lost connection with
termination and/or bias.
Bus (-) Open - The bus (-) wire has lost connection with termination and/or bias.
Not Receiving Bus Messages Correctly - The DRB cannot communicate over the bus and does not know why.
Using the DRB
USING THE DRB
Refer to the DRB user guide for instructions and assistance with reading trouble codes, erasing trouble codes, and other DRB functions.
Vehicle Communication
VEHICLE COMMUNICATION
The Chrysler Collision Detection multiplex system (CCD bus) consists of a twisted pair of wires. These wires run from one module to another.
They receive and deliver coded information between the modules. The information is coded to identify the message as well as the importance of
the message. When there are multiple messages trying to access the CCD bus at one time, the code determines the message that has higher priority,
which is then allowed to access the bus first.
The two wires of the twisted pair that make up the CCD multiplex system are called "bus +" (bus plus) and "bus -" (bus minus) respectively. Each
wire has a measurable voltage level of roughly 2.5 volts. In order to maintain the 2.5 volts on each line and provide a means of transportation for
the coded messages, there is a "voltage divider network". This network consists of some modules with bias and some with termination. Bias is the
part of the voltage divider network that places both bus + and bus - at 2.5 volts. Termination in the circuitry is required to complete the voltage
divider network and also provides some electromagnetic protection for the bus.
NOTE: Communication over the bus is essential to the proper operation of the vehicle's on-board diagnostic systems and the DRB. Problems with
the operation of the bus or DRB must be corrected before proceeding with diagnostic testing.
Description of Vehicle Information Center
VEHICLE INFORMATION CENTER
The Vehicle Information System (VIC) is located below the radio in the center stack. The VIC consists of a multicolored vacuum fluorescent (VF)
