Perkins NJ Series Troubleshooting Manual page 201

SENR9982-01
If the test ECM fixes the fault, reconnect the
suspect ECM.
If the fault returns with the suspect ECM, replace
the ECM.
Use the electronic service tool in order to clear all
logged diagnostic codes and then verify that the
repair eliminates the fault.
STOP.
Test Step 10. Check the Engine Harness
Under the Valve Cover for a Short Circuit
Electrical shock hazard. The electronic unit injec-
tor system uses 67-73 volts.
A. Turn the keyswitch to the OFF position. A strong
electrical shock hazard is present if the keyswitch
is not turned OFF.
B. Remove the valve cover.
C. Disconnect each of the injectors that indicate a
"Short" from the wiring harness. Ensure that each
of the connectors from the disconnected injector
harness does not touch any other components.
D. Turn the keyswitch to the ON position.
E. Perform the "Injector Solenoid Test" at least two
times.
Expected Result:
All of the injectors that were disconnected indicate
"Current Below Normal".
Results:
•
OK – All of the injectors that were disconnected
indicate "Current Below Normal".
Repair: Leave the injector wires disconnected.
The supply wire is not shorted to the engine.
Proceed to Test Step 11.
• Not OK – One or more of the injectors that were
disconnected indicate "Current Above Normal".
Repair: The fault is most likely in the supply to the
injector. Inspect the connectors for moisture and for
corrosion. Also, check the supply wire's insulation
for damage and for strands that are exposed.
Repair the injector harness or replace the injector
harness under the valve cover.
Use the electronic service tool to clear all logged
diagnostic codes and then verify that the repair has
eliminated the fault.
STOP.
Test Step 11. Check for a Short Circuit in
the Return Wire
Electrical shock hazard. The electronic unit injec-
tor system uses 67-73 volts.
A. Turn the keyswitch to the OFF position. A strong
electrical shock hazard is present if the keyswitch
is not turned OFF.
B. Disconnect the connector P2 from the ECM.
C. Locate the terminal for the supply of the faulty
injector in the connector P2. Measure the
resistance from the terminal to the engine ground
stud.
Expected Result:
The resistance is greater than 10 Ohms.
Results:
• OK – The resistance is greater than 10 Ohms.
Repair: Reconnect connector P2.
Replace the faulty injector.
Perform the "Injector Solenoid Test".
Use the electronic service tool in order to clear all
logged diagnostic codes and then verify that the
repair eliminates the fault.
STOP.
•
Not OK – There is a short in the return line.
Repair: Disconnect the connectors from the valve
cover base.
Measure the resistance of the return wire between
connector P2 and the engine ground stud.
If the resistance is less than 10 Ohms, the fault is
in the return wire between the ECM and the valve
cover base.
If the resistance is greater than 10 Ohms, the fault
is in the return wire under the valve cover.
Repair the injector harness or replace the injector
harness.
201
Troubleshooting Section