Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
2002 Jeep Liberty Limited, 4WD, Part TimeFACTORY OEM SERVICE PROCEDURE
Bus Messages Missing
Possible Causes:
- No Response From CMTC
- Intermittent Condition
- No Response-PCI Bus-PCM
- No Response-PCI Bus-BCM
- Compass Mini-Trip Computer
Testing
- Turn the ignition off. Perform the CMTC self test. To perform CMTC self test manually, depress and hold the STEP and C/T CMTC buttons while turning the ignition on. Does the CMTC display "PASS"? If yes, go to next step. If no, go to step 4 .
- Turn the ignition on. With the DRBIII(R), select Body Computer, System Tests then PCM Monitor. Does the DRBIII(R) display "PCM Active on the Bus"? If yes, go to next step. If no, refer to COMMUNICATION in DIAGNOSTIC TROUBLE CODE IDENTIFICATION or SYMPTOM IDENTIFICATION tables for the related symptom(s).
- Turn the ignition on. With the DRBIII(R), attempt to I/D or communicate with the BCM. Was the DRBIII(R) able to I/D or communicate with the BCM? If yes, replace the Compass Mini-Trip Computer OVERHEAD CONSOLES - LIBERTY for REMOVAL & INSTALLATION. Perform BODY VERIFICATION TEST . If no, refer to COMMUNICATION in DIAGNOSTIC TROUBLE CODE IDENTIFICATION or SYMPTOM IDENTIFICATION tables for the related symptom(s).
- Turn the ignition off. Perform the CMTC self test. Does the CMTC display "BUS"? If yes, refer to symptom BUS +/- Signals Open Or No Response From Compass Mini-Trip Computer in the COMMUNICATION category. If no, the condition is not present at this time. Monitor DRBIII(R) parameters while wiggling the related wire harness. Refer to any Technical Service Bulletins (TSB) that may apply. Visually inspect the related wiring harness and connector terminals.
NOTE:
The CMTC self test can performed manually or by using the DRBIII(R).
Factory Service Tools
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.