Hi Amith,
I would like to map same data Vehicle Object to Service work order Object which have master-details relationship.I tried that code but it not working,Please find the code in below:It is in bold and italic:

trigger ServiceLifeTimeValue on Service_Work_Order__c (after insert, after update)
{
    
    if (Trigger.isAfter && (Trigger.isInsert || Trigger.isUpdate))
    {
        Set<String> setStrVINNumber = new Set<String>();
        Set<String> setStrVINNumber1 = new Set<String>();
        Map<String, Decimal> mapStrVINNumToTotal = new Map<String, Decimal>();
        List<Vehicle__c> lstVehicleToUpdate = new List<Vehicle__c>();
        
        // iterate over SWOs and collect VIN numbers
        for(Service_Work_Order__c objSWO : Trigger.New)
        {
            setStrVINNumber.add(objSWO.Workorder_VIN_Number__c);
        }
        
        // calculate sum
        for(AggregateResult objAR : [   SELECT SUM(Test_Total_Work_Order_Cost_ExGST__c) total,  Workorder_VIN_Number__c VIN
                                        FROM Service_Work_Order__c 
                                        WHERE Workorder_VIN_Number__c IN :setStrVINNumber GROUP BY Workorder_VIN_Number__c] )
        {
            mapStrVINNumToTotal.put((String)objAR.get('VIN'),(Decimal)objAR.get('total'));
        }
        
        // iterate over matching vehicles and update the total amount.
        for(Vehicle__c objVehicle : [   SELECT Id,Test_service_life_time_value__c ,Name
                                        FROM Vehicle__c 
                                        WHERE Name IN :setStrVINNumber])
        {
        
            if(mapStrVINNumToTotal.containsKey(objVehicle.Name))
            {
                objVehicle.Test_service_life_time_value__c =  mapStrVINNumToTotal.get(objVehicle.Name);
                lstVehicleToUpdate.add(objVehicle);
                
              /*/////////////////////////////////////////////////////////////*/
                       for(Vehicle__c objVehicle1 : [   SELECT Id,Test_service_life_time_value__c ,Name
                                        FROM Vehicle__c 
                                        WHERE Name IN :setStrVINNumber])
        {
        setStrVINNumber1.add(objVehicle1.Id);
       
              
              
              for(Vehicle_Ownership__c objAVO : [   SELECT Id,VIN__c,Test_Roll__c ,Name
                                        FROM Vehicle_Ownership__c 
                                        WHERE VIN__c IN :setStrVINNumber1 AND Customer_Vehicle_Relationship_Status__c='Active'])
             
                  {                      
                  objAVO.Test_Roll__c=objVehicle1.Test_service_life_time_value__c ;
                //lstVehicleToUpdate.add(objVehicle);       }                
                     }
                /*/////////////////////////////////////////////////////////////*/
                     }
        }
        
        // update vehicles - If any exception occurs, it throw an error - so passed 'true' 
        if(lstVehicleToUpdate.size() > 0 ) // check list size before DML
        {
            DataBase.Update(lstVehicleToUpdate, true);
        }                    
            
              
        }
    }
}