Perkins 1104E Series Troubleshooting Manual page 151

RENR2696-01
Illustration 67
Bypass harness
Note: This bypass harness is only for test
applications. This bypass harness may be left only
temporarily on the engine. The bypass harness
can be used in order to determine if the cause of
the intermittent problem is the interruption of the
power supply from the battery to the ECM or to the
keyswitch circuit.
A. Turn the keyswitch to the OFF position.
B. Disconnect harness connector J1/P1 from the
ECM.
C. Remove the 20 Amp in-line fuse from the bypass
harness and connect the harness to the ECM
connector J1.
Note: This bypass directly connects the circuit for the
keyswitch to the ECM. The ECM will remain powered
until the connection to the unswitched battery line "+"
is disconnected from the battery post. The removal of
the 20 Amp fuse will ensure that the ECM will remain
without power while connections are being made.
The 20 Amp fuse should also be removed before
disconnecting the battery connections.
D. Connect an electronic service tool to the Data
Link connector. Connect the unswitched + battery
and the negative wire of the battery directly to
the battery posts in order to ensure the correct
polarity.
E. Replace the 20 Amp in-line fuse. Verify
that communication from the service tool is
established. Perform any necessary diagnostic
tests.
F. Remove the 20 Amp in-line fuse. Disconnect the
bypass harness. Restore all wiring to the original
condition. Replace the fuse in the disconnected
bypass harness.
Expected Result:
Installing the bypass eliminates the problem.
Results:
•
OK – The symptoms disappear when the bypass
harness is installed. Also, the symptoms return
when the bypass harness is removed. The problem
is in the wiring that supplies power to the ECM.
Repair the wiring that supplies power to the ECM.
STOP.
•
Not OK
151
Troubleshooting Section
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