CAP 2457851 - Caterpillar

System Operation Description:Use this procedure to determine if the neutral switch is preventing normal operation of cruise control, idle set speed, or PTO operation:The following switch circuits can also prevent the correct operation of the cruise control, idle set speed or PTO operation:
Service Brake Pedal Position (Switch 1)
Service Brake Pedal Position (Switch 2)
Cruise Control Set/Resume Switch
Cruise Control On/Off Switch
PTO On/Off SwitchThe switches are described in the respective circuit tests in Troubleshooting.All of the following customer programmable parameters can affect cruise control, idle set speed, and PTO operation:
"Low Cruise Control Speed Set Limit"
"High Cruise Control Speed Set Limit"
"Idle Vehicle Speed Limit"
"Cruise/Idle/PTO Switch Configuration"
"Idle/PTO Bump rpm"
"Idle/PTO rpm Ramp Rate"
"PTO Vehicle Speed Limit"The vehicle speed calibration can also affect the cruise control, the idle set speed, and the PTO if the vehicle speed calibration is incorrectly programmed. Refer to Troubleshooting, "Customer Specified Parameters".Transmission Neutral SwitchWith software prior to DEC03, the transmission neutral switch is required when the "Transmission Style" parameter is programmed to "Automatic Option 3" or "Automatic Option 4". This switch is used to indicate when the automatic transmission is in neutral.With DEC03 software, the neutral switch is now independent from the "Transmission Style" parameter. Programming the neutral switch, but not connecting the neutral switch can prevent the "Idle Set Speed", "Cruise Control", and "PTO" parameters from functioning properly.The transmission neutral switch is an open circuit when the transmission is in gear. Shifting the transmission to the neutral position should close the circuit, which connects the input to the battery voltage. Many other switches in the system connect the input to ground when the circuit is closed.Usage of Transmission Style Switches (DEC03 and later software)The "Transmission Style" parameter determines the switches that will be used. The following switches can be used with being dependent on the parameter setting:
Clutch Pedal Position
Neutral
Service Brake Pedal Position (Switch 1)
Service Brake Pedal Position (Switch 2)Refer to Table 1 for additional information.
Table 1
Setting For Transmission Style Parameter     Switch Usage.    
Service Brake 1 Service Brake 2     Clutch     Neutral    
Manual Option 1     X         X        
Automatic Option 1     X                
Automatic Option 2     X     X            
Automatic Option 3     X     X         X    
Automatic Option 4     X             X    
Eaton Top 2     X         X        A service brake pedal position (Switch 1) is required for all configurations. The service brake pedal position (Switch 1) connects to the ECM through connector P1:45. The service brake pedal position (Switch 2) connects to the ECM through connector P1:64. The neutral switch connects to the ECM through connector P1:62. With DEC03 software, the neutral switch can also connect to the ECM through J1939.
Illustration