Test Step 4. Check ECM Operation of Wait to Start Lamp

420

TM 9-2320-312-24-2

Troubleshooting Section

C. Connect one probe of the voltage test lamp to

Results:

terminal 65 (-battery). Connect the other probe of

Result 1 The wait to start lamp is functioning

the voltage test lamp to terminal 52 (unswitched

+battery) of the breakout T.

properly. Proceed to Test Step 4.

Result 2 The lamp did not turn on. The vehicle's

D. The test lamp should turn on. If the test lamp

does not turn on, either the test lamp is faulty or

lamp circuit is not functioning properly. The lamp

the wiring to the ECM is faulty. Continue with this

is probably burned out or there is a problem in

step if the lamp turns on.

the wiring from the cab to either the ECM or the

+Battery connection. Repair the lamp circuit or

E. Leave the probe of the test lamp connected to

send the vehicle to the OEM dealer for repairs.

terminal 52 (unswitched +battery).

STOP.

Result 3

F. Connect the other probe of the test lamp to

terminal 31 (output 9) of the breakout T.

Repair: Perform the following diagnostic

Refer to Illustration 192.

procedure:

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

The circuit between the ECM and the lamp is

shorted to chassis ground. Repair the circuit or

H. Connect ET to the cab data link connector.

send the vehicle to the OEM dealer for repairs.

Access the configuration screen and ensure that

the "Output #9" parameter is programmed to

STOP.

"Wait To Start Lamp".

Test Step 4. Check ECM Operation of

Wait to Start Lamp.

I. Turn the ignition key switch to the OFF position

for ten seconds. Turn the ignition key switch to

the ON position.

J. The wait to start lamp should illuminate for

approximately two seconds when the key switch

is turned on. If conditions require the air inlet

heater to turn on, the wait to start lamp should

remain illuminated until the air inlet heater turns

off or the engine is started.

Expected Result:

The test lamp turns on and the test lamp turns off

per the above description.

Results:

Yes The ECM is operating correctly. There is a

problem in the vehicle wiring or the lamp. STOP.

g00770221

Illustration 192

Repair: Temporarily connect a test ECM. Ensure

ECM breakout T-connector

that the "Output #9" parameter is programmed to

"Wait To Start Lamp". Check the ECM operation

A. Disconnect ECM vehicle harness connector

of the PTO Switch ON Lamp when the test ECM

J1/P1.

is installed. If the problem is resolved with the test

ECM, reconnect the suspect ECM. If the problem

B. Insert a breakout T between ECM vehicle

returns with the suspect ECM, replace the ECM.

harness connector J1 and ECM vehicle harness

connector P1.

STOP.