Grand Cherokee 2WD Limited V8-4.7L (2002)
Body Control Module: Component Tests and General Diagnostics
Road Testing A Complaint Vehicle
ROAD TEST WARNINGS
Some complaints will require a test drive as part of the repair verification procedure. The purpose of the test drive is to try to duplicate the diagnostic
code or symptom condition.
CAUTION: Before road testing a vehicle, be sure that all components are reassembled. During the test drive, do not try to read the DRB III screen
while in motion. Do not hang the DRB III from the rear view mirror or operate it yourself. Have an assistant available to operate the DRB III.
Six Step Troubleshooting Procedure
SIX-STEP TROUBLESHOOTING PROCEDURE
Diagnosis is done in six basic steps:
1. Verification of complaint
2. Verification of any related symptoms
3. Symptom analysis
4. Problem isolation
5. Repair of isolated problem
6. Verification of proper operation
Vehicle Preparation For Testing
VEHICLE PREPARATION FOR TESTING
Make sure the vehicle being tested has a fully charged battery. If it does not, false diagnostic codes or error messages may occur.
Description of On-Board Diagnostics
DESCRIPTION OF ON-BOARD DIAGNOSTICS
The hard wired inputs to and outputs from the Body Control Module (BCM) may be diagnosed and tested using conventional diagnostic tools and
procedures. Refer to the appropriate wiring information.
Conventional diagnostic methods may not prove conclusive in the diagnosis of the BCM. In order to obtain conclusive testing of the BCM, the
Programmable Communications Interface (PCI) data bus network and all of the electronic modules that provide inputs to or receive outputs from the
BCM must also be checked. The most reliable, efficient, and accurate means to diagnose the BCM, the PCI data bus network, and the electronic
modules that provide inputs to or receive outputs from the BCM requires the use of a DRB III scan tool and the appropriate diagnostic information.
The DRB III scan tool can provide confirmation that the PCI data bus network is functional, that all of the modules are sending and receiving the
proper messages over the PCI data bus, and that the BCM is receiving the proper hard wired inputs and responding with the proper hard wired outputs
needed to perform its many functions.
WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS, DISABLE THE AIRBAG SYSTEM BEFORE ATTEMPTING ANY
STEERING WHEEL, STEERING COLUMN, OR INSTRUMENT PANEL COMPONENT DIAGNOSIS OR SERVICE. DISCONNECT
AND ISOLATE THE BATTERY NEGATIVE (GROUND) CABLE, THEN WAIT TWO MINUTES FOR THE AIRBAG SYSTEM
CAPACITOR TO DISCHARGE BEFORE PERFORMING FURTHER DIAGNOSIS OR SERVICE. THIS IS THE ONLY SURE WAY TO
DISABLE THE AIRBAG SYSTEM. FAILURE TO TAKE THE PROPER PRECAUTIONS COULD RESULT IN ACCIDENTAL AIRBAG
DEPLOYMENT AND POSSIBLE PERSONAL INJURY.
