Dear Pooja,
What is the fleet size of the vehicles in your company? Does the movement of the vehicles take place only within the city or vehicles go out of the city as well? What type of vehicles your company has?
Irrespective of the replies to the above questions, preparation of the SOPs for the Maintenance Department is the primary job of HOD of that department? Being from the HR department, why you have been assigned to this task? Yes, you may assist that HOD but this cannot be your primary activity.
Preparation of the SOPs is a long-drawn process. One needs to understand the types of vehicles used, education and skill level of the technicians, whether they have understood the concept of the first-line servicing and second-line servicing etc. Even if you hire a technical consultant, it could take a few weeks for him to understand the systems and processes of the department and he will able to design SOPs thereafter.
Thanks,
Dinesh Divekar