Test Step 5. Install the Bypass Harness for the Engine Speed/Timing Sensors

259

TM 9-2320-312-24-2

Troubleshooting Section

Not OK The sensor resistance is out of the

E. Start the engine in order to determine if the

bypass harness repairs the problem.

range.

Repair: Perform the following procedure in order

Expected Result:

to check and install the new sensor:

The problem is corrected with the installation of the

bypass harness.

1. Before installing the new sensor, measure the

resistance of the new sensor.

Results:

Note: If the new sensor resistance is not in the

OK The bypass harness corrected the problem.

correct range, inspect the wiring harness for

damage.

Repair: Permanently install a new section of

If the new sensor resistance is in the correct

harness.

range, install the new sensor in the engine,

as follows:

STOP.

Not OK The bypass harness did not correct

a. Loosen the bolt that holds the sensor

mounting bracket to the engine.

the problem.

b. Ensure that one O-ring is installed and free

Repair: Verify that the correct terminals have been

of damage.

installed in the correct location of the ECM engine

harness connector P2. If the temporary harness

c. Seat the sensor and tighten the bolt.

was installed correctly, install the original wiring.

If the sensor will not seat, repair the sensor

Proceed to Test Step 6.

or replace the sensor, as required.

Test Step 6. Check the ECM

Note: The sensor must not be removed from the

bracket.

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

d. Ensure that the sensor is properly oriented

B. Temporarily connect a test ECM.

and that the harness is secured in the

proper location.

C. Start the engine. Run the engine in order to

repeat the conditions when the problem occurs.

2. Verify that the repair eliminates the problem.

D. If the problem is resolved with the test ECM,

STOP.

reconnect the suspect ECM.

Test Step 5. Install the Bypass Harness

E. If the problem returns with the suspect ECM,

for the Engine Speed/Timing Sensors

replace the ECM.

Verify that the repair eliminates the problem.

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

Expected Result:

B. Disconnect ECM connector J2/P2.

The problem remains with the suspect ECM.

C. Install the wiring harness to the ECM engine

harness connector P2. Connect the wiring:

Results:

P2:48 to the white wire

OK The problem is resolved with the test ECM

and the problem returns with the suspect ECM.

P2:49 to the black wire

Replace the ECM. Verify that the repair eliminates

the problem. STOP.

P2:58 to the yellow wire

Not OK The problem was not resolved with a

P2:59 to the blue wire

test ECM.

Note: Twisted pair wiring is required. Ensure that the

Repair: Replace the sensor.

wires have at least one twist per inch.

Verify that the repair eliminates the problem.

D. Reconnect the engine harness connector J2/P2.

STOP.