Maintenance SOP 032: Preventative Maintenance 


This procedure provides information for mechanics and technicians to maintain the CAD/AVL system. The process includes procedures for 6000 mile and 12000 mile intervals, and covers maintenance for system start up, mobile data terminals, mobile handset, emergency alarm switch, APC, AVA, internal LED signs, public address equipment, headsign, and farebox equipment. 

Operational Impact and Metrics  

Operational Impact: Performing regular preventive maintenance prevents downtime of CAD/AVL system and ensures data integrity.  

Metrics: On-time performance, pull-out %, vehicle availability 


ITS  Intelligent Transportation Systems 
CAD/AVL  Computer-Aided Dispatch and Automatic Vehicle Location 
MDT  Mobile Data Terminal 
IEB  Interface Expansion Box 
PM  Preventative Maintenance 
AVA  Automatic Vehicle Announcement 
APC  Automatic Passenger Counter 
IVU  In-Vehicle Logic Unit 


Every 6000 miles and 12000 miles for each vehicle. See section VI for details.

Roles and Responsibilities  

Implementation of this SOP is primarily the responsibility of Vehicle Mechanics/Technicians.  Maintenance Supervisors should also be familiar with these procedures to support the technicians (see SP-033-01).  


Refer to articles for detailed steps to perform CAD/AVL 6000- and 12000-mile preventive maintenance.  

6000 Mile AVL equipment Preventive Maintenance – Check the following items and indicate “pass or fail”. Refer to AVL service manual for diagnosis and repair information to correct deficiencies. It is recommended to integrate this checklist into the full PM documentation for your fleet. 

  1. System Start up  
  2. Mobile Data Terminal (MDT) Care & Handling 
  3. Mobile Data Terminal (MDT) PM Service - All MDT Models 
  4. Radio Handset PM Service (if equipped) 
  5. Emergency Alarm Switch PM Service 
  6. Automatic Passenger Counter (APC) PM Service (if equipped) 
  7. Automatic Vehicle Announcement (AVA) PM Service 
  8. Internal LED Sign PM Service 
  9. Public Address (PA) System PM Service 
  10. Headsign Interface PM Service 
  11. Fare Box Interface PM Service (if equipped) 

12000 Mile (or monthly) PM service - Complete all items from the 6000 mile (or biweekly PM service). Then proceed to check these additional items: 

  1. GPS Antenna PM Service (if equipped) 
  2. Radio Antenna PM service (if equipped) 
  3. IEB PM Service (if equipped) 
  4. Annunciator PM service (if equipped) 
  5. IVU PM Service (if equipped) 
  6. PA Amplifier PM Service (if equipped) 
  7. Power Filter PM Service (if equipped) 
  8. J1708 Box PM Service (if equipped) 

Supporting Documents  

  1. Related Training Material 
  2. Other Maintenance role SOPs 
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