Test Step 3. Check the Switch Circuit for the ECM -807640526

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TM 9-2320-312-24-2

Troubleshooting Section

Test Step 3. Check the Switch Circuit for

the ECM.

g00839604

Illustration 151

Breakout T

1. Temporarily connect a test ECM.

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

2. Remove all jumpers and replace all connectors.

B. Install a breakout T to the ECM connector J1/P1.

3. Recheck the system for active diagnostic

C. Fabricate a jumper wire 100 mm (4 inch) long.

codes.

Crimp a Deutsch pin to both ends of the wire.

4. Repeat the test step.

D. Insert the jumper wire into terminal 7 or terminal

23 of the breakout T. Connect the other end of

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

the jumper wire to terminal 3 in the breakout T.

reconnect the suspect ECM.

Terminal 3 is sensor common.

6. If the problem returns with the suspect ECM,

E. Connect ET to the cab data link connector.

replace the ECM.

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

7. Verify that the repair eliminates the problem.

G. Alternately remove the jumper wire and then

insert the jumper wire from terminal 5. At the

STOP.

same time, monitor the status screen on ET.

Test Step 4. Insert a Jumper Wire at the

Switch.

Expected Result:

The status of the switch changes to "ON" with

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

the jumper wire in place. The status of the switch

changes to "OFF" when the jumper wire is removed.

B. Reconnect the ECM vehicle harness connector

J1/P1.

Results:

C. Fabricate a jumper wire 100 mm (4 inch) long.

Yes The ECM is functioning properly at this

Crimp a Deutsch pin to both ends of the wire.

time. Proceed to Test Step 4.

D. Insert the jumper wire between the two switch

No The ECM is not functioning properly.

terminals.

Repair: Perform the following repair:

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