Ignition Key Switch Circuit and Battery Supply Circuit

287

TM 9-2320-312-24-2

Troubleshooting Section

Test Step 3. Check the State of the

Result 4 The engine is not at low idle.

Related Conditions When the Vehicle is

Parked.

Repair: Return the engine to Low Idle. Perform

the test procedure again.

A. Check the state of the following related conditions

STOP.

when the vehicle is parked:

Ensure that the vehicle speed is 0 km/h

i01632013

(0 mph) on ET or the dash display.

Ignition Key Switch Circuit and

Ensure that the engine is not in cold mode.

Battery Supply Circuit - Test

(The ET status screen will indicate that "Cold

Mode" is "Active" in the corner of the display

SMCS Code: 1408-081; 1553-081

screen.)

System Operation Description:

Ensure that the PTO on/off switch is OFF.

Use this procedure under the following situation:

Ensure that the engine is at low idle.

This procedure tests whether proper voltage is

Expected Result:

supplied by vehicle wiring. Use this procedure

if any one of the following diagnostic codes are

Result 1 Vehicle speed is not indicated as 0 km/h

logged several times:

(0 mph).

168-02 Intermittent Battery (51)

Result 2 The ET status screen indicates that the

engine is in cold mode.

43-02 Ignition Key Switch Fault (71)

Result 3 The status of the PTO on/off switch is not

Also, use this procedure if you suspect that the

"OFF".

ECM is not receiving the battery supply voltage.

Result 4 The engine is not at low idle.

Note: This code can be generated by rapidly

cycling the ignition key switch. Some control

Results:

modules on the vehicle require this action in order

to prompt flash codes. If this occurs, clear the

Result 1 Vehicle speed is not indicated as

logged diagnostic codes in order to prevent future

0 km/h (0 mph).

confusion or an incorrect diagnosis.

Repair: Perform the following diagnostic

The following background information is related

procedure: Troubleshooting, "Vehicle Speed

to this procedure:

Circuit - Test"

The ECM receives electrical power (battery voltage)

STOP.

through the wiring that is supplied by the vehicle

manufacturer. The ECM input at connector P1

Result 2 The ET status screen indicates that the

terminal 70 (ignition key switch) receives battery

engine is in cold mode.

voltage from the ignition key switch when the

ignition key switch is in the ON position or the

Repair: The engine must not be in "Cold Mode"

START position. When the ECM detects battery

operation while this test procedure is being

voltage at this input, the ECM will power up. When

performed. Allow the engine to run until the

battery voltage is removed from this input, the ECM

coolant temperature exceeds 20 C (68 F).

will power down.

Troubleshoot and repair any related conditions.

The cause of an intermittent power supply to

STOP.

the ECM can occur on either the positive side

(unswitched +battery) or the negative side

Result 3 The status of the PTO on/off switch

(-battery). Both sides are routed from the ECM

is not "OFF".

to the battery. The two unswitched +battery

connections should be routed through a dedicated

Repair: Perform the following diagnostic

protection circuit.

procedure: Troubleshooting, "PTO Switch Circuit -

Test"

STOP.