Test Step 4. Check ECM Operation of the PTO Switch On Lamp

365

TM 9-2320-312-24-2

Troubleshooting Section

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

lamp circuit is not functioning properly. The lamp

is probably burned out or there is a problem in

the wiring from the cab to either the ECM or the

+Battery connection. Repair the lamp circuit or

send the vehicle to the OEM dealer for repairs.

STOP.

Result 3

Repair: Perform the following diagnostic

procedure:

The circuit between the ECM and the lamp is

shorted to chassis ground. Repair the circuit or

send the vehicle to the OEM dealer for repairs.

STOP.

Test Step 4. Check ECM Operation of the

PTO Switch On Lamp.

g00642533

Illustration 163

ECM Breakout T-connector

G. Connect ET. Access the following display

A. Disconnect ECM vehicle harness connector

screens in order:

J1/P1.

"Diagnostics"

B. Insert a breakout T between ECM vehicle

harness connector J1 and ECM vehicle harness

"Diagnostic Test"

connector P1.

"Special Test"

C. Connect one probe of the voltage test lamp to

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

the voltage test lamp to terminal 52 (unswitched

H. Activate the special test for the PTO Switch ON

+battery) of the breakout T.

Lamp. Observe the voltage test lamp. The lamp

should turn on when the test is active. Also, the

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

lamp should turn off when the test is inactive.

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

the wiring to the ECM is faulty. Continue with this

Expected Result:

step if the lamp turns ON.

The test lamp turns on and the test lamp turns off

E. Leave the probe of the test lamp connected to

per the above description.

terminal 52 (unswitched +battery).

Results:

F. Connect the other probe of the test lamp to

Yes The ECM is operating correctly. There is a

terminal 30 (Output 1) of the breakout T.

problem in the vehicle wiring or the lamp. STOP.

Refer to Illustration 163.