With - BMW Diagnostic System

Notes on the BMW DIAGNOSTIC SYSTEM:

Initialization of Diagnostic Procedure:

Communication with the control unit via the DIAGNOSTIC SYSTEM can be set up after selecting the DME on the BMW SERVICE TESTER. If data transfer is interrupted, information appears on the display screen indicating the possible cause:

- Ignition not switched on
- Voltage supply for control unit < 10 V
- DME relay not supplied with B+ (if not, bypass terminal 30 and 87)
- Control unit not connected
- Diagnostic link defective
- Data traffic inhibited by a defective control unit in the vehicle

Control Unit Assignment:

The identification data appear first in order to determine whether the correct control unit is installed. The assignment can be made by means of the variant code (e.g. C01E) and the parts microfiche without having to remove the control unit.

Explanation of Control Unit Identification:

The designation of the DME version appears in the first line.

Further data are displayed in the sequence shown below:

- Variant: Model designation, engine type
- With or without emission control
- Transmission variant:
HG - Manual transmission
AG - Automatic transmission, hydraulic
EH - Automatic transmission, electronic-hydraulic
- Type of fuel: Leaded/unleaded or regular/premium
- Country version: International identification
- Control unit variant code: See parts microfiche
- BMW hardware and software number
- Bosch hardware and software number
- Production code: Used only on special request by "Service Division"

Effective Range of the Self-diagnosis Function:

The self-diagnosis function is an aid to facilitate fast fault tracing in the vehicle's electrical/electronic systems. The BMW DIAGNOSTIC SYSTEM (Service Tester, MoDiC) provides the necessary access for the user. Self-diagnosis of the control units detects defects provided the necessary conditions for this have been fulfilled (time, temperature, load etc.). However, defects can only be registered when there is an electrical connection to the control unit. If this is not the case, the check must be performed using conventional methods (e.g. ignition voltage, fuel pressure, mechanical functions etc.).

Storage of Defect Codes:

Defect codes are stored after the engine has been started. If several defects are detected, they appear in the order they first occurred.

The operating conditions as stored apply only to the conditions, under which the defect was detected for the first time. An intact voltage supply (charged battery) is the prerequisite for maintaining the memory contents.

Substitute values may be active if no malfunction can be found despite a defect code being stored. Troubleshooting should still, however, be carried out.

In US models, defects which influence the fuel/air mixture are indicated by a lamp (check engine) in the instrument cluster. As a check, this lamp lights constantly during the period of time between "ignition ON" and engine start.

If the defect code memory has no defect code stored although there is a defect in the vehicle, either the test conditions (e.g. temperature, time, load etc.) for defect detection were not fulfilled or it was technically not possible to store a defect code. A list of monitored components and functions is given in the chapter - Component Testing -.

Defect Code Memory Monitoring •D• 900:

The first step should always be to monitor the defect code memory. If one or several defect codes are stored, it is advisable to print out these data immediately (R key). Since it is often necessary during the testing procedure to cut the power supply or to disconnect the connector from the control unit, the contents of the defect code memory will be unintentionally deleted as a consequence.

The learned adaptation values are lost if the battery or the DME control unit is disconnected. This may result in difficulties in starting the engine or the engine may stall when idling. These problems are generally rectified after a short test drive.

DME M1.1 and M1.3 Model '87/'88:

The memory can hold a maximum of 5 defect codes, whereby a defect code with high priority displaces another defect code out of the memory. The defect codes are displayed in the same order, in which they were detected.

The following defect codes are stored with higher priority:

- Air flow meter
- Emission (lambda) control
- Engine temperature sensor
- Idle switch

DME M1.3 from Model '89:

The extended defect code memory contains all defect codes which are detected. If a defect code is stored and the DME shows no signs of any defects, substitute values may be active. Troubleshooting, however, should still be carried out.

Clearing the Defect Code Memory •D• 999:

Carry out this step only when all defects have been rectified or caused by simulation. When the battery or the DME control unit are disconnected, all stored defect codes, the substitute values (if active) as well as the adaptation values are lost. Current defects cannot be cleared.

Status Monitoring •D• 100and •D• 200:

Further current data can be called up independently of the defect code storage function. Current values or operating statuses are displayed. Refer to - Component Testing - for the necessary comparison of nominal values.

Status inquiries can also be made from the blocks 100 and 200 as required. This selection (termed extract list) is made by entering the corresponding number followed by the acknowledgement. The selection is then displayed on the screen with the "down arrow" key.

If status monitoring takes place while the engine is running, an engine speed of 2000 rpm should not be exceeded otherwise faults may be experienced in data transfer.

Component Activation •D• 300:

To facilitate fast fault finding, various components can be activated from the SERVICE TESTER in conjunction with the DME control unit. The response of components in perfect working order including their supply lines, can therefore be by acoustic means.

Activation is only possible with the component connected. For this reason, signal testing is not possible at the disconnected component connector. This function provides a simple means of differentiation between defects in the control unit, on the supply wire or in the component itself. More detailed information on component activation is provided on the display screen.

Print out Check Code:

If a printout of the identification page is requested. the printer prints out the check code. This printout contains the contents of the defect code memory in concise form and should be sent in together with the defective component in warranty cases.

Troubleshooting:

Notes:

Relevant safety codes and accident prevention regulations must be observed when carrying out all tests and work on the engine electrical and electronic systems.

Caution!

Dangerous high tension in the primary and secondary circuit of the ignition system.

Wherever possible, the battery should not be disconnected, otherwise the defect codes stored in all the control units will be deleted.

Disconnect control units from the wire harness only when the ignition is switched off.

Conduct wire tests only with the control unit or component connectors disconnected.

Test Equipment:

The schematics can be found in Diagrams / Electrical.

The universal adapter with the corresponding connection leads should be used for testing the DME control unit or the engine wire harness.

The universal adapter should only be connected between the control unit and wire harness when no diagnostic procedure ([1][2]diagnostic connector not connected) is to be carried out since this can lead to malfunctions. Use only suitable test leads, terminals and probe tips.

Display of a Stored Error Code on the Screen:

- Defect location: The number of the defect code indicates the pin assignments at the control unit. The defect can be in the vicinity of the component, the corresponding wiring or in the control unit.

- Type of defect: Short-circuits, breaks, range transgressions or illogical functions are indicated.

- Frequency: indication as to whether the defect is momentary or not (intermittent defect). Further indication is provided as to whether the defect occurred several times or only once.

As of model '89 an indication is provided as to how often the defect has already been detected. If the defect is no longer pending, the number of starts is indicated which have taken place since last detection of the defect.

- Detected at: Additional defect information on the operating statuses during defect detection.