130-2
Electrical Checks and
Component Testing
Troubleshooting and fault diagnosis on
OBD II cars is best performed using an
electronic scan tool. However, it may
be necessary to perform basic tests of
the engine management main
components, fuel system or wiring.
CAUTION!
The tests in this section may set
fault codes (DTCs) in the ECM
and illuminate the MIL. After all
testing tests is completed,
access and clear DTC fault
memory using a BMW
compatible scan tool. See
OBD On Board Diagnostics
at
the back of this manual.
Only use a digital multimeter for
electrical tests.
Relay positions can vary. Be
sure to confirm relay position by
identifying the wiring in the
socket using the wiring
diagrams found at the rear of
this manual.
DME main relay, testing
The DME main relay is energized via
the engine control module (ECM) and
supplies battery positive (B+) power to
many of the engine management
components and subsystems. If this
relay is faulty, the engine will not start.
With ignition off, remove main relay
(
arrow
) in electronics box (E-box) at
Fuel Injection
http://ebahn.bentleypublishers.com/BMW/3/E46/Repair%20Manuals/1...
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Summary of Contents for 1999-2005 M3
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