Kohler Command PRO ECH630 Service Manual page 37

Service
Never att empt to disassemble the ECU. It is sealed to
prevent damage to internal components. Warranty
is void if the case is opened or tampered with in any
way.
All operating and control functions within the ECU
are preset. No internal servicing or readjustment may
be performed. If a problem is encountered, and you
determine the ECU to be faulty, contact your source
of supply. Do not replace the ECU without factory
authorization.
The ECU pins are coated at the factory with a thin
layer of electrical grease to prevent frett ing and
corrosion. Do not att empt to remove the grease from
the ECU pins.
The relationship between the ECU and the thrott le
position sensor (TPS) is very critical to proper
system operation. If the TPS or ECU is changed,
or the mounting position of the TPS is altered, the
appropriate TPS Learn Procedure (see page 5.11) must
be performed to restore the synchronization.
Wiring Harness
9 1
18 10
Figure 5-2. ECU Connectors.
General
The wiring harness used in the EFI system connects
the electrical components, providing current and
ground paths for the system to operate. All input
and output signaling occurs through two special
all weather connectors that att ach and lock to the
ECU. The connectors are Black and Grey and keyed
diff erently to prevent being att ached to the ECU
incorrectly. See Figure 5-2.
9 1
18 10
The condition of the wiring, connectors, and
terminal connections is essential to system function
and performance. Corrosion, moisture, and poor
connections are as likely the cause of operating
problems and system errors as an actual component.
Refer to the Electrical System section for additional
information.
Electrical System
The EFI system is a 12 VDC negative ground system,
designed to operate down to a minimum of 6.0
volts. If system voltage drops below this level, the
operation of voltage sensitive components such as the
ECU, fuel pump, ignition coils, and injectors will be
intermitt ent or disrupted, causing erratic operation
or hard starting. A fully charged, 12 volt batt ery with
a minimum of 350 cold cranking amps is important
in maintaining steady and reliable system operation.
Batt ery condition and state of charge should always
be checked fi rst when troubleshooting an operational
problem.
Keep in mind that EFI-related problems are oft en
caused by the wiring harness or connections. Even
small amounts of corrosion or oxidation on the
terminals can interfere with the milliamp currents
used in system operation.
Cleaning the connectors and grounds will solve
problems in many cases. In an emergency situation,
simply disconnecting and reconnecting the connectors
may clean up the contacts enough to restore
operation, at least temporarily.
If a fault code indicates a problem with an electrical
component, disconnect the ECU connector and test
for continuity between the component connector
terminals and the corresponding terminals in the ECU
connector using an ohmmeter. Litt le or no resistance
should be measured, indicating that the wiring of that
particular circuit is OK.
NOTE: When performing voltage or continuity
tests, avoid putt ing excessive pressure on or
against the connector pins. Flat pin probes
are recommended for testing to avoid
spreading or bending the terminals.
Section 5
EFI Fuel System
5.5
5