Test Step 4. Use the Injector Solenoid Test to Test the Injector Solenoids

315

TM 9-2320-312-24-2

Troubleshooting Section

I. Verify that cutting out a specific cylinder causes

G. Activate the test.

only a slight change to the Fuel Position of the

other cylinders in comparison to the change

Note: Do not confuse the Injector Solenoid Test with

to the Fuel Position that occurs when other

the Cylinder Cutout Test. The Cylinder Cutout Test

cylinders are cut out. If a cylinder is cut out and

is used to shut off fuel to a specific cylinder while

only a slight change occurs to the Fuel Position

the engine is running. The Injector Solenoid Test

of the other cylinders, a mechanical problem

is used in order to actuate the injector solenoids.

with the injector or a mechanical problem with

This allows the click of the injector solenoids to be

the cylinder may exist.

heard when the engine is not running in order to

determine that the circuit is functioning properly.

J. After the test is finished, use ET to check for

active diagnostic codes or for logged diagnostic

H. As each solenoid is energized by the ECM an

codes that are new.

audible click can be heard at the valve cover.

A black square will appear over the cylinder

number when the cylinder is being fired.

Expected Result:

An active diagnostic code for a cylinder fault results

I. Perform the Injector Solenoid Test at least two

from running the Cylinder Cutout Test.

times.

Results:

Expected Result:

Yes Proceed to Test Step 4.

All cylinders indicate "OK".

No Perform the following repair:

Results:

Yes There is not an electronic problem with the

Repair: If a cylinder is cut out and only a slight

change occurs to the Fuel Position of the other

injectors at this time. STOP.

cylinders, a mechanical problem with the injector

No ET displays "SHORT" for any cylinder.

or a mechanical problem with the cylinder

may exist. If the engine is misfiring or if the

Proceed to Test Step 5.

engine has low power, refer to Troubleshooting,

No ET displays "OPEN" for any cylinder.

"Engine Misfires, Runs Rough or Is Unstable"

and Troubleshooting, "Low Power/Poor or No

Proceed to Test Step 6.

Response to Throttle".

Test Step 5. Check the Injector Harness

from P2 to J300 for Short Circuits.

If a diagnostic code for a cylinder fault results

from running the Cylinder Cutout test, proceed

to Test Step 4.

Test Step 4. Use the Injector Solenoid

Electrical shock hazard. The electronic unit injec-

Test to Test the Injector Solenoids.

tor system uses 90-120 volts.

A. Start the engine.

A. Turn the ignition key switch to the OFF position.

A strong electrical shock hazard is present if the

B. Allow the engine to warm up to 77 C (171 F)

ignition key switch is not turned off.

which is the normal operating temperature.

B. Disconnect the 12-pin connector (J300/P300).

C. Turn the ignition key switch to the OFF position.

Check for evidence of moisture entry. Refer

to Troubleshooting, "Electrical Connectors -

D. Connect ET at the cab data link connector.

Inspect" for details.

E. Turn the ignition key switch to the ON position.

C. Turn the ignition key switch to the ON position.

F. After the engine is warmed to operating

D. Access the "Injector Solenoid Test" on ET and

temperature, access the "Injector Solenoid Test"

begin the test.

by accessing the following display screens in

order:

"Diagnostics"

"Diagnostic Tests"

"Injector Solenoid Test"