BMW 1989-1995 525i Service Manual page 188

130-20
FUEL INJECTION-DME
ECM PIN ASSIGNMENTS
ECM pin assignments are given in Table e th rough h. This
information can be helpful when diagnosing faults to or from
the ECM. If all inputs and wiring are OK but operational prob -
lems still exist . the ECM itself may be faulty.
Generally. absence of voltage or continu ity means there is
a wiring or connector problem. Test results with incorrect val-
ues do not necessarily mean that a component is faulty.
Check for loose , broken or corroded connections and wiring
before replacing components. If the results are still incorrect.
test the component itself. For electrical schematics of the
DME system. see Electrical Wiring Diagrams.
CAUTlON -
• Always wait at least 40 seconds alter turning off
the ignition before removing the connector from
the engine control module (£ CM).
If
the connec-
tor
is
removed before this time. residual power in
the system relay may damag e the ECM.
• Always connect or disconnect the contro l module
connector and meter probes with the ignition off.
When making checks at the ECM itself. a breakout box
should be used to allow tests to be made with the connector
attached to the ECM. This also prevents damage to the small
terminals in the connector. As an alternat ive. the harness con-
nector housing can be separated so that electrica l checks can
be made from the back of the connector.
ECM PIN ASSIGNMENTS
The ECM is mounted in the right rear of the engine compart-
ment, inside the electron ics box (E-box). See Fig. 29. Termi-
nal numbers are identified on the harness connector and/or
on the ECM.
Fig . 29. DME enqme control module harness connector (arrow ).
CAUTION -
Use only
a
high-quality digital multimeter (DVOM)
when making electrical checks at ECM or other
solid state DME components.