Functions of bus system analysis

Bus system analysis is a test module that automatically executes the following steps:

1. Step 1: Identification of engine type 

   Identifying the engine type is a prerequisite for bus system analysis, since: different engines generate different fault code memory entries for the same cause of fault.

2. Step 2: Read fault memories of all control units 
3. Step 3: Check fault memory entries for undervoltage 

   If the vehicle has suffered an undervoltage, the undervoltage is the most likely cause of the bus failure. Bus system analysis checks whether a fault memory entry indicating undervoltage is present in at least 2 control units. If no undervoltage can be detected, continue with step 4.

4. Step 4: Check how many fault memory entries were found 

   If at least 1 fault memory entry is present, continue with step 5.

5. Step 5: Evaluation of fault memory entries and creation of a list of most probable fault causes 

   Bus system analysis computes the 3 most probable fault causes.

   The 3 most probable fault causes are given in a list.

   The most probable fault cause is at the top of the list.

   REFERENCE CHART
   
   

   Message in the BMW diagnosis system
   The fault causes detected are as follows:
   [1] ** ** Cause of fault PT-CAN
   [2] ** Cause of fault ZGM
   [3] * Cause of fault...
   [4] End test module
   The more stars (maximum 5) are allocated to a component, the more reliable the result that the cause of the fault is to be found in the area of the component.

   NOTE: The number of stars denotes priority.

   The stars in front of a cause of fault indicate how probable the cause of fault is. 5 stars denote the most likely cause of fault.

   1 star is allocated to a cause of fault that has very low probability.

6. Step 6: Selection of the test module 

   The BMW diagnosis system proposes a separate test plan for each of the 3 most probable fault causes.