BMW 5 Series E39

since 1996-2001 release

Repair and operation of the car

Description of system of onboard diagnostics

(In case of the equipment of your OBD II car on Schild under a cowl there has to be a record "OBD II compliant" and there has to be a 16-contact socket. As a rule, OBD II are equipped North American models, since 1996 release and the European models, since 2000 release)

Several diagnostic devices making monitoring of separate parameters of systems of decrease in toxicity and fixing the revealed refusals in memory of the onboard processor in the form of individual codes of malfunctions are a part of the OBD system. The system makes also check of sensors and actuation mechanisms, controls vehicle service cycles, provides a possibility of storing even of the failures which are quickly arising in the course of work and cleaning of the block of memory.

The models described in the present manual are equipped with system of onboard diagnostics. A basic element of system is the onboard processor more often called by the electronic module of management (ESM), or the module of management of functioning of the power unit (RSM). RSM is a brain of a control system of the engine. Basic data arrive on the module from various information sensors and other electronic components (switches, the relay, etc.). On the basis of the analysis of the data arriving from information sensors, and according to the basic parameters put in the processor memory, RSM develops commands for operation of various operating relays and actuation mechanisms, carrying out thereby adjustment of working parameters of the engine and providing maximum efficiency of its return at the minimum fuel consumption. Data read-out of the processor memory is made by means of the special scanner connected to the 16-contact diagnostic socket of reading of the database (DLC) located on the average console or to the 20-contact diagnostic socket located at the left in a motive compartment.

Special guarantee certificates with the extended validity extend to service of components of control systems of engine/decrease in toxicity of the fulfilled gases. It is not necessary to make attempts of independent performance of failure diagnostics of RSM or replacement of components of system, to an exit of terms of these obligations, - address specialists of company car repair shops.

Reading of codes of malfunctions

The DME (SAE J1979) codes are transferred by the 8-digit binary word (byte). Each category (bit) reflects result of check of a certain electric chain of a control system, and accepts value 0 - if the test passed, and 1 - if malfunction is found.

Example of information byte and value of its categories

Information contents of categories of the 5-digit SAE code

Look P 0 3 8 0 from left to right:

1 category
   -  P power unit
   -  B body
   -  With the chassis
2 category Code Source
   -  0 standard SAE
   -  1 set BMW
3 category System
   -  0 system in general
   -  1 admixture of air (air/fuel induction)
   -  2 injections of fuel
   -  3rd system of ignition or admissions of ignition
   -  4th additional control of release
   -  5th speed of the car and management х.х.
   -  6 entrance and output signals of the control unit
   -  7th transmission
4,5 categories Serial number of malfunction of a component or chain (00-99)

Purpose of conclusions of the 20-contact diagnostic socket

Reading of codes of malfunctions

At detection of the malfunction repeating in a row on two trips, RSM issues the command for inclusion of the control lamp which is built in in an instrument guard "Check the engine", called also by the indicator of refusals. The lamp will continue to burn until memory of system of self-diagnostics is not cleared of the codes of the revealed malfunctions brought in it. Reading of codes of malfunctions in the OBD system can be made by means of the devices described above connected to the diagnostic socket. Other ways are possible not on all models. The blinking code can be считан on a lamp "Check the engine".