Common Sense Hints

- Always "check the basics": look for such obvious problems as battery state of charge, loose battery cables, defective fuses, etc. Very few things are as discouraging as troubleshooting alternator noise in a sound system for four hours, only to discover that a partially discharged battery was causing increased alternator current and ripple.








- When reading the fault memory of a control module with the diagnostic link, remember that the message "no faults found" simply means that all monitored circuits are intact and within limits. Some circuits cannot be monitored for faults; for example, it is "okay" for the stop light switch to be either open or closed as far as the control module is concerned - check the switch operation by monitoring its status.






- Intermittent electrical problems can be difficult to diagnose. Gather as much information as possible from the customer concerning the conditions under which the problem occurs - this may provide valuable diagnostic clues.


- When trying to locate an intermittent open or short in a circuit, attach the meter to the circuit (according to the test being performed) and flex, twist, pull and shake the harness or wire in question. Refer to Section 0130 of the Diagnostic Manual for meter and BMW Service Tester hookups.



- If unapproved accessories are installed, they should be disconnected electrically from the vehicle's original harnesses - if they are not, voltage and resistance measurements may be erroneous. Such unapproved accessories may in fact be the cause of the malfunction being diagnosed.



- Always write down all of your measurements. If the BMW Technical Hotline is contacted, the Technical Specialists must have all of this information.



- Any problems which elude BMW Diagnostic Procedures must be reported to BMW.



Please follow these procedures whenever troubleshooting electrical problems. A systematic, thorough approach to troubleshooting is one of the easiest ways to ensure customer satisfaction, by finding and repairing electrical problems quickly and correctly.