Cherokee 4WD L6-4.0L VIN S (1998)
Information Bus: Description and Operation
System Description and Functional Operation
SYSTEM DESCRIPTION AND FUNCTIONAL OPERATION
The body system on the 1997 and 1998 Jeep Cherokee consists of four modules that communicate over the CCD bus (Chrysler Collision Detection
multiplex system). There are two additional modules, the Powertrain Control Module (PCM) and the Transmission Control Module (TCM) that are not
part of the body system, but do utilize the CCD bus for communication. The TCM also utilizes the bus for diagnostics. The PCM sends and receives
messages on the CCD bus; however, diagnostics are performed through the Serial Communication Interface or SCI, the same as last year. All of the
information about the functioning of all the systems is organized, controlled and communicated by the CCD bus.
Through the CCD bus, information about the operation of vehicle components and circuits is relayed quickly to the appropriate module(s). All modules
receive all the information transmitted on the bus although a module may not require all information to perform its function. Each module will only
respond to messages "addressed" to it through a binary coding process. This method of data transmission significantly reduces the complexity of the
wiring in the vehicle and the size of wiring harnesses.
Introduction
INTRODUCTION
The procedures contained here include all the specifications, instructions and graphics needed to diagnose 1997 and 1998 XJ Jeep Cherokee. These
diagnostics are based on the failure condition or symptom being present at the time of diagnosis.
Diagnostic procedures change every year. New diagnostic systems may be added; carryover systems may be enhanced. It is recommended that you
review the entire section to become familiar with all new and changed diagnostic procedures. Begin all diagnosis at symptom identification test. This will
cover all the necessary requirements to begin a logical diagnostic path for each repair. If there is a trouble code detected, it will direct you to a specific
test. If it is a symptom problem, it will direct you to a SYSTEM TEST 1 A for more specific instructions or directly to a specific test. Side headers are
used to direct you alphabetically to the specific systems.
DRBIII Safety Information
WARNING: Exceeding the limits of the DRB multimeter is dangerous. It can expose you to serious or possibly fatal injury. Carefully read and
understand the cautions and the specification limits.
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Follow the vehicle manufacturer's service specifications at all times.
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Do not use the DRB if it has been damaged.
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Do not use the test leads if the insulation is damaged or it metal is exposed.
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To avoid electrical shock, do not touch the test leads, tips, or the circuit being tested.
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Choose the proper range and function for the measurement. Do not try voltage or current measurements that may exceed the rated capacity.
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Do not exceed the limits shown in the table below:
FUNCTION INPUT LIMIT
Volts
0 - 500 peak volts AC
0 - 500 volts DC
Ohms (resistance)*
0 - 1.12 megohms
Frequency Measured
0 - 10 kHz
Frequency Generated
Temperature
-58-1100°F
-50 - 600°C
