Check Cold Mode Operation

TM 9-2320-312-24-2

Troubleshooting Section

If the accelerator pedal position is unstable,

2. Check Cold Mode Operation.

check the Accelerator Pedal Position Duty

Cycle. Check the Accelerator Pedal Position

Note: This is normal operation if the problem occurs

Duty Cycle by slowly operating the accelerator

only after start-up in cold weather.

pedal in order to verify that the Accelerator

Pedal Position Sensor is within calibration.

a. Connect an Electronic Service Tool.

The Accelerator Pedal Position Sensor is

within calibration when both of the following

b. Monitor the Electronic Service Tool in order to

conditions are met:

verify that the engine has progressed from

Cold Mode.

10 to 22 percent at low idle

An Active Cold Mode is indicated in the upper

75 to 90 percent at high idle

corner of any Status Screen.

3. Check for an Electronic System problem.

Also, ensure that the duty cycle changes as

the pedal position changes.

a. Connect an Electronic Service Tool.

If a problem with the Accelerator Pedal

b. Monitor the Fuel Position, the Rated Fuel Limit,

Position Sensor is suspected, refer to

and the FRC Fuel Limit.

Troubleshooting, "Accelerator Pedal (Throttle)

Position Sensor Circuit - Test".

While the vehicle is operating under full load,

the parameters should meet the following

Note: If the engine exceeds the "Top Engine Limit",

conditions:

the "Top Engine Limit with Droop" is programmed

to YES.

The Fuel Position is equal to the Rated Fuel

5. Monitor the vehicle speed signal. Ensure

Limit.

the accuracy of the vehicle speed signal by

The Fuel Position is less than the FRC Fuel

comparing the vehicle speed signal to the actual

vehicle speed.

Limit.

If the vehicle speed is greater than the VSL, the

If the Fuel Position is equal to the Rated Fuel

Power is limited. If a problem is discovered, refer

Limit and the Fuel Position is less than the

to Troubleshooting, "Vehicle Speed Circuit - Test".

FRC Fuel Limit, the Electronics are operating

correctly. Go to Step 5.

6. Check the "Power train Data Link". Ensure that

the SAE J1922 or the SAE J1939 Power train

4. If the Fuel Position is not equal to the Rated Fuel

Data Link is not limiting the power.

Limit and/or the Fuel Position is not less than

the FRC Fuel Limit, perform the following tests

a. Connect an Electronic Service Tool.

in order:

b. Monitor the "Power train Data Link" Status

a. Connect an Electronic Service Tool.

screen while the vehicle is experiencing

problems.

b. When the engine is OFF, turn the Ignition Key

Switch to the ON position. Check the boost

If the "Power train Data Link" Status screen

pressure on an Electronic Service Tool Status

indicates that the "Power train Data Link" is

Screen.

limiting the power or the rpm, verify that this

is not normal operation. If this is not normal

When the engine is OFF, the boost pressure

operation, refer to the vehicle OEM for repairs.

should be 0 kPa (0 psi).

7. Check the fuel supply.

c. Monitor the status of the Accelerator Pedal

Position Sensor. Operate the engine at high

a. Monitor the exhaust for smoke while the

idle with the vehicle in Neutral.

engine is being cranked.

If the engine can not reach the programmed

If no smoke is present, there may be a

"Top Engine Limit", check the Accelerator

problem with the fuel quality or there may be

Pedal Duty Cycle in order to ensure that

a problem with the fuel supply.

the Accelerator Pedal Duty Cycle is within

calibration (75 to 90 Percent at high idle).