Test Step 7. Use ET to Check the ECM

217

TM 9-2320-312-24-2

Troubleshooting Section

Test Step 7. Use ET to Check the ECM.

g00676088

Illustration 72

Connector for the Breakout T

A. Connect ET to the cab data link connector.

Repair: If a problem still exists, then the problem

is in the OEM Wiring. Repair the problem or send

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

the vehicle to the OEM dealer for repair. Verify

that the repair eliminates the problem.

C. Disconnect the ECM vehicle harness connector

J1/P1.

STOP.

D. Remove terminal 41 (output 11) from the vehicle

harness connector P1.

Repair: Temporarily connect a test ECM. Ensure

E. Install a breakout T between connectors J1 and

that the "A/C Pressure Switch Fan On-Time"

P1.

parameter is programmed in the same manner as

the suspect ECM. Use ET to check the ECM. If

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

the problem is resolved with the test ECM, install

Crimp a Deutsch pin to both ends of the wire.

the suspect ECM. If the problem returns with the

suspect ECM, replace the ECM.

G. Connect the jumper wire to terminal 5 (ap

sensor/switch common) and to terminal 41 (input

Verify that the repair eliminates the problem.

11) of the breakout T.

STOP.

Refer to illustration 72.

Test Step 8. Use ET to Check Inlet

Manifold Air Temperature and the

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

Coolant Temperature.

I. Access the "A/C High Pressure Switch" status

screen on ET.

A. Connect ET to the cab data link connector.

J. Remove the jumper wire and then insert the

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

jumper wire. At the same time, watch the "A/C

High Pressure Switch" status on ET.

C. Access the status screen. Locate the "Coolant

Temperature" and the "Inlet Manifold Air

Expected Result:

Temperature" status screen. Monitor the status

screen for a few minutes in order to verify that

The status screen indicates that the "A/C High

the temperatures are changing as the engine

Pressure Switch" status is OFF when the jumper

warms up.

wire is in place. The status screen indicates ON

when the jumper wire is removed.

Expected Result:

Results:

The "Coolant Temperature" and the "Inlet Manifold

Air Temperature" appear to have the correct

Yes The ECM is OK.

reading.