DTC xx099 Internal - Fault
POSSIBLE CAUSE A. INTERNAL FAULT COMPONENT OPERATIONAL CHECK NOTE: Always check battery condition and state of charge before performing electrical troubleshooting. A faulty or low charged battery will cause electrical features to not operate as designed and give incorrect readings while performing electrical tests. PROCEDURE OR ACTION: 1. Conduct a visual inspection of all connectors/wiring associated with the fault code. Are any faults detected/observed? YES: Repair/replace connector or wiring associated with faults found. Refer to the appropriate Electrical System SRM. NO: Proceed to Step 2. 2. Re-key the vehicle. Is the code still present? YES: Proceed to Cause A. NO: Problem may be intermittent. CAUSE A - INTERNAL FAULT PROCEDURE OR ACTION: 1. Replace faulty controller. Make sure to indicate the DTC code(s) on the warranty claim to include an accurate problem description leading to controller replacement.
END POSSIBLE CAUSES

You sure that is a fault code,dont find anything like that for the B60Z trucks....what is the complete model and serial number of the truck????