Can Not Reach Vehicle Speed Limit

TM 9-2320-312-24-2

Troubleshooting Section

Fuel Supply

Customer Specified Parameters (normal

operation)

1. Check the fuel supply.

Cold Mode Operation

2. Monitor the exhaust for smoke while the engine

Electronic System problem

is being cranked.

Fuel supply

If no smoke is present, there may be a problem

with the fuel quality or there may be a problem

Air Inlet System or Exhaust System

with the fuel supply.

Leakage in Air-to-Air Aftercooler Core

3. Check the fuel quality. Refer to the Truck

Performance and Driveability Diagnostic Guide,

LEBT3477.

Recommended Actions

4. Check the fuel pressure. Refer to Testing and

Perform the following diagnostic procedures in

Adjusting, "Fuel System Pressure - Test".

order:

5. Ensure that the fuel system has been primed.

1. Check Customer Specified Parameters.

Refer to Testing and Adjusting, "Fuel System -

Prime".

a. Verify that the complaint is not normal

operation (programmed parameter).

6. Check for fuel supply lines that are restricted.

b. Connect an Electronic Service Tool.

7. Check the fuel filters.

c. Check the following parameters:

8. If the temperature is below 0 C (32 F), check

for solidified fuel (wax).

"Vehicle Speed Limit"

9. Check for air in the fuel system. Refer to Testing

"Soft Vehicle Speed Limit"

and Adjusting, "Air in Fuel - Test".

"Lower Gears Engine RPM Limit"

Dedicated PTO Switch On or Torque Limit

Switch always On

"Intermediate Gears Engine RPM Limit"

"Gear Down Protection Engine RPM Limit"

Check the parameter setting for the Dedicated PTO

parameter. If the "Torque Limit" is programmed

"VSL Protection"

below 2720 Nm (2000 lb ft) check the status screen

for "Input No. 1" and "Input No. 2". Ensure that the

"Top Engine Limit"

status indicates "OFF".

Incorrect programming of the Vehicle Speed

Note: The system is operating correctly if the torque

calibration (ppm).

limit is programmed and the status is "On". If the

PTO switch is connected to the PTO input and

"PTO Top Engine Limit" with the PTO On/Off

the PTO switch is not switching on or off refer to

Switch turned ON.

Troubleshooting, "PTO Switch Circuit - Test".

"PTO Vehicle Speed Limit" with the PTO

i01191584

On/Off Switch turned ON.

Can Not Reach Vehicle Speed

d. Set each parameter to the parameter's

Limit

maximum value one at a time and determine

whether the problem is corrected.

SMCS Code: 7569

Note: The "Soft Vehicle Speed Limit" will not allow

the vehicle to achieve the programmed VSL under

Probable Causes

all engine load conditions. Programming the "Soft

Vehicle Speed Limit" to NO may be required to

The probable root causes are listed in order below:

eliminate the complaint.