On/Off switch for Cruise Control and Idle Control

TM 9-2320-312-24-2

Troubleshooting Section

"High Cruise Control Set Speed Limit"

If ET indicates "Bad Vehicle Speed", "Vehicle

Speed < Limit" or "Vehicle Speed >= Limit" go

"Idle Vehicle Speed Limit"

to Step 4.

"Idle rpm Limit"

2. If ET indicates "Switch Turned Off", the ECM has

detected an open circuit in the on/off switch

circuit. This pertains to the cruise control, the

Note: If the vehicle speed exceeds the "High Cruise

idle control or the PTO. Perform the following

Control Set Speed Limit" and the driver attempts to

tests in order:

set a cruise control speed, the cruise set speed will

be the "High Cruise Control Set Speed Limit". If the

a. Ensure that the operator has not actually

vehicle speed is below the "Low Cruise Control Set

turned off the cruise control on/off switch or

Speed Limit", the cruise control can not be set or

the PTO on/off switch.

resumed. If the engine rpm is above the idle rpm

limit and the driver attempts to set an idle engine

b. Check the ET status screen while the switch

rpm the idle engine rpm will be the idle rpm limit. If

is being used. If the problem is not apparent

the driver attempts to set an idle engine rpm and the

check the switch and the wiring.

vehicle speed exceeds the idle vehicle speed limit,

the idle will not activate. Refer to Troubleshooting,

c. If the problem is related to the cruise control

"Cruise Control Switch Circuit - Test".

or idle control refer to Troubleshooting, "Cruise

Control Switch Circuit - Test ", Troubleshooting,

On/Off switch for Cruise Control

"Service Brake Pedal Position (Switch 1)

and Idle Control

Circuit - Test", and Troubleshooting, "Clutch

Pedal Position Switch Circuit - Test".

When the PTO is set by using a dedicated PTO

on/off switch, use ET to check Customer Specified

d. If the problem is related to the PTO refer to

Parameters. Check the following parameters:

Troubleshooting, "PTO Switch Circuit - Test".

"PTO Vehicle Speed Limit"

3. If ET indicates "Brake", "Clutch" or "Neutral", the

ECM has detected an open circuit in the switch

"PTO Top Engine Limit"

circuit for the service brake, the switch circuit

for the clutch or the transmission neutral switch

If the vehicle speed exceeds the programmed "PTO

circuit. Perform the following tests in order:

VSL", the ECM will not maintain the set speed.

Typically, the operation of the PTO requires an

a. Ensure that the operator has not actually

interlock switch such as a parking brake switch.

depressed the service brake pedal or the

Ensure that all interlocks are set to allow PTO

clutch pedal. Also ensure that the operator

operation. Refer to Troubleshooting, "PTO Switch

has not actually shifted the transmission to

Circuit - Test" for additional information.

neutral.

b. Check the ET status screen while the service

ET Status Screen

brake or the clutch is being used. If the

problem is not apparent check the switches.

1. Connect ET to the cab data link connector.

Check the service brake switch for the air

Check the status screen for the last item that

system. Ensure that the treadle valve is

caused the kickout for the cruise control, the idle

operating freely. A treadle valve that is not

control or the PTO control.

operating freely can cause pressure spikes.

Check the clutch switch adjustment and the

Note: ET will only provide access to the last cause

return spring.

of the kickout. If the ECM is powered down and

the ECM is powered up, the ET display will be

c. If the problem is related to the cruise control

blank. The ECM is powered down when the ignition

or idle control refer to Troubleshooting, "Cruise

key switch is turned to the OFF position. It may

Control Switch Circuit - Test ", Troubleshooting,

be necessary to take the vehicle for a test drive in

"Service Brake Pedal Position (Switch 1)

order to repeat the problem. Check the ET before

Circuit - Test", and Troubleshooting, "Clutch

the ECM is turned off by the keyswitch.

Pedal Position Switch Circuit - Test".

If ET indicates "Switch Turned Off", go to Step 2.

d. If the problem is related to the PTO refer to

Troubleshooting, "PTO Switch Circuit - Test".

If ET indicates "Brake", "Clutch" or "Neutral" go

to Step 3.