Test Step 10. Bypass the Harness Wiring Between the ECM and the Sensor Connector

251

TM 9-2320-312-24-2

Troubleshooting Section

3. Verify that the repair eliminates the problem.

6. If the problem returns with the suspect ECM,

replace the ECM.

STOP.

7. Verify that the repair eliminates the problem.

Not OK Restart this procedure and carefully

perform each step. STOP.

STOP.

Test Step 10. Bypass the Harness

i01606388

Wiring Between the ECM and the Sensor

Connector.

Engine Running Output Circuit

- Test

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

SMCS Code: 1900-081

B. Disconnect ECM engine harness connector

J2/P2, and the sensor connector.

System Operation Description:

C. Remove the sensor signal wire from ECM

Use this procedure under the following situation:

connector P2 on the engine harness.

Use this procedure in order to determine if the

D. Remove the signal wire (terminal "C") from the

circuit for the Engine Running Output is operating

sensor connector on the engine harness .

properly.

E. Fabricate a jumper wire that is long enough to

The following background information is related

reach from the ECM to the sensor connector or

to this procedure:

use an engine sensor harness bypass with 3

terminals.

Personality Modules that have a Software Date

Code dated earlier than OCT01.

Note: If an engine sensor harness bypass is being

made, crimp a Deutsch socket on one end in order

The Engine Running Output is located on ECM

to connect to the ECM. Crimp either a Deutsch pin

J1/P1:13 (Output 4).

or a Deutsch socket on the other end, as required.

The engine running output comes on when the

F. Insert the engine sensor harness bypass into

engine is running. The engine running output turns

the ECM connector P2 on the engine harness.

off when the engine rpm equals 0. This can be

Insert the other end of the engine sensor harness

used to prevent the engagement of the starter

bypass into the sensor connector of the engine

motor while the engine is running. The ECM can

harness .

be connected to a relay that disables the starter.

The relay is normally closed so cranking can be

G. Reconnect ECM engine harness connector J2/P2

achieved immediately at powerup. During cranking,

and the sensor connector.

the ECM energizes the engine running output once

engine rpm reaches 50 rpm below low idle. The

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

output is de-energized if the engine speed falls

below the programmed low idle by 100 rpm. The

I. Monitor the "Active Diagnostic Code" screen for

low idle rpm is programmable. The range for low

either the open circuit diagnostic code for the

idle is between 700 rpm and 800 rpm.

sensor or the short circuit diagnostic code for

the sensor.

Expected Result:

The diagnostic code disappears when the jumper

or the bypass is installed.

Results:

OK There is a problem in the wiring harness.

Repair: Perform the following repair:

1. Repair the faulty wiring harness or replace the

faulty wiring harness.

2. Clear all diagnostic codes.