Engine Controls - System & Component Testing: Introduction
NOTE:
BMW troubleshooting charts, guides and aids for diagnosis are integrated into BMW-specific service tools. BMW does not have or supply stand-alone guides for testing or troubleshooting. All OBD-II equipped BMWs are designed to be programmed and coded electronically. Diagnosis, coding, and programming on any OBD-II BMW may be carried out with BMW's DISplus, Group Tester 1 (GT1) or similar scan tool.
Before testing separate components or systems, perform procedures in BASIC DIAGNOSTIC PROCEDURES article. Since many computer-controlled and monitored components set a trouble code if they malfunction, also perform procedures in SELF-DIAGNOSTICS - EXCEPT 7-SERIES or SELF DIAGNOSTICS - 7-SERIES article.
NOTE:
BMW diagnostic hardware, such as DISplus/GT1 as well as a reputable hand held multimeter should be used when testing inputs and components. Slack Tube Manometer Test Tool (99 00 0 001 410) should be used to troubleshoot crankcase ventilation valves. It is best to make the checks at the ECM connection, as this method includes testing the wiring harness. The correct universal adapter for engine and model being tested should be used. This will ensure the pin connectors and the harness will not be damaged. When installing the universal adapter to the ECM (located in the electronics box in the engine compartment), make sure the ignition is switched off. On Siemens MS45, allow at least 3 minutes to elapse after the key was set to OFF position before disconnecting ECM/TCM. This will allow sufficient time to complete the DM TL test. Voltage may be present (up to 3 minutes) causing damage to the ECM/TCM if they are disconnected during this time period.