Engine Controls - Self-Diagnosis - Tests With Codes: Introduction

If no faults were found while performing appropriate BASIC TESTING, proceed with self-diagnostics. BMW vehicles are equipped with 2 separate self-diagnostic systems. OBD-II self-diagnostic system accesses Diagnostic Trouble Codes (DLCs) using a generic scan tool connected to vehicle Data Link Connector (DLC). See Fig 1-Fig 3 . BMW self-diagnostic system accesses DTCs using special BMW hardware and software connected to BMW engine diagnostic connector socket. See Fig 4 and Fig 5 .

Regardless of self-diagnostic system, DME/Motronic control unit provides a substitute value if a failure occurs in an engine performance related component, such as engine (coolant) temperature sensor, intake air temperature sensor, airflow meter or exhaust gas oxygen sensor. See 1996 MODEL COVERAGE table. These substitute values are canceled when normal engine operation is resumed.

NOTE: All voltage tests should be performed with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless specifically stated otherwise in testing procedures.

Fig 1: Locating OBD-II Data Link Connector (Z3)

G98D11281

Courtesy of BMW OF NORTH AMERICA, INC.

Fig 2: Locating OBD-II Data Link Connector (3 & 8-Series)

G98E11282

Courtesy of BMW OF NORTH AMERICA, INC.

Fig 3: Locating OBD-II Data Link Connector (7-Series)

G98F11283

Courtesy of BMW OF NORTH AMERICA, INC.

Fig 4: Locating BMW Engine Diagnostic Connector Socket (4-Cylinder Engine Shown; Others Are Similar)

G98G11284

Courtesy of BMW OF NORTH AMERICA, INC.

Fig 5: Identifying BMW Engine Diagnostic Connector Socket

G97A04282

Courtesy of BMW OF NORTH AMERICA, INC.

The Motronic/Siemens control unit provides a substitute value if a failure occurs in an engine performance related component, such as engine (coolant) temperature sensor, intake air temperature sensor, airflow meter or exhaust gas oxygen sensor. These substitute values are canceled when normal engine operation is resumed.

If no DTCs are present after entering self-diagnostics, proceed to TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.).

NOTE: All voltage tests should be performed with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless specifically stated otherwise in testing procedures.

1996 MODEL COVERAGE

⁽¹⁾Model

⁽²⁾ Engine

Engine Type

Z3

1.9L 4-Cyl.

M44

318i

1.9L 4-Cyl.

M44

318is

1.9L 4-Cyl.

M44

318ti

1.9L 4-Cyl.

M44

328i

2.8L 6-Cyl.

M52

328is

2.8L 6-Cyl.

M52

740i

4.4L V8

M62

740iL

4.4L V8

M62

750iL

5.4L V12

M73

840Ci

4.4L V8

M62

850Ci

5.4L V12

M73

⁽¹⁾	Model code designated by 4th through 7th VIN positions identifies body type and engine identification.

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⁽²⁾	Engine is identified as part of 4-digit model code

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