Automatic Transmission Neutral Switch

325

TM 9-2320-312-24-2

Troubleshooting Section

The automatic transmission neutral switch is an

The following switch circuits can also prevent the

open circuit when the transmission is in gear.

correct operation of the cruise control, fast idle, idle

Shifting the transmission to the neutral position

set speed or PTO operation:

should close the circuit, which connects the input

Service brake pedal position (switch 1)

to the battery voltage. Many other switches in the

system connect the input to ground when the circuit

Service brake pedal position (switch 2)

is closed.

Neutral switch

This switch may not be connected to an input on

the ECM. The parameter "Transmission Neutral

Cruise control set/resume switch

Switch" determines the input to the ECM. If the

parameter is programmed to J1/P1:62 a switch

Cruise control on/off switch

must be connected to terminal 62. If the parameter

is programmed to "J1939", the switch position will

PTO on/off switch

be transmitted to the ECM over the J1939 data

link. If a problem is suspected with the J1939 data

cruise control pause switch

link, refer to Troubleshooting, "Powertrain Data Link

Circuit - Test".

The switches are described in the respective circuit

The following background information is related

tests in Troubleshooting.

to this procedure:

All of the following Customer Programmable

The kickout switch refers to the switch that is used

Parameters can affect cruise control, fast idle, idle

to exit the cruise control, the fast idle, the PTO, or

set speed, and PTO operation:

the idle set speed.

"Low Cruise Control Speed Set Limit"

The operation of the Caterpillar electronic engine

"High Cruise Control Speed Set Limit"

cruise control is similar to the operation of the

cruise controls that are installed in automobiles. The

"Idle Vehicle Speed Limit"

operation of fast idle, idle, and PTO are similar to

the operation of cruise except that the idle and the

"Fast Idle RPM #1"

PTO govern engine rpm instead of vehicle speed.

"Fast Idle RPM #2"

Note: Idle in this procedure is an engine idle rpm

above the programmed low idle rpm. Idle is set

"Cruise/Idle/PTO Switch Configuration"

by using the cruise control on/off switch and the

set/resume switch. Refer to Troubleshooting, "PTO

"Idle/PTO Bump rpm"

Switch Circuit - Test" for additional information

regarding the programmable options for the

"Idle/PTO rpm Ramp Rate"

Dedicated PTO.

"PTO Vehicle Speed Limit"

Note: Fast idle in this procedure is an engine idle

rpm above the programmed low idle rpm. Fast idle

"Cruise Pause Switch"

is set by using a dedicated fast idle switch.

Cruise Control On/Off Switch

The vehicle speed calibration can also affect

the Cruise Control, the Idle Set Speed, and the

This switch must be ON before cruise control or

PTO if the vehicle speed calibration is incorrectly

controlled idle can be activated. This switch is

programmed. Refer to Troubleshooting, "Customer

ON when the switch is closed. When the switch is

Specified Parameters".

closed the following terminals are connected:

Automatic Transmission Neutral Switch

ECM connector J1/P1 terminal 59 (cruise control

The automatic transmission neutral switch is

on/off switch)

required when the "Transmission Style" parameter

Terminal 5 (AP sensor/switch sensor common)

is programmed to "Automatic Option 3", "Automatic

Option 4", "AT/MT/HT Option 3", or "AT/MT/HT

Option 4". This switch is used to indicate when the

Note: If the vehicle is programmed to use the

automatic transmission is in neutral.

"Dedicated PTO", the PTO on/off switch overrides

the cruise control on/off switch. The PTO on/off

switch overrides the cruise control on/off switch

when the vehicle speed is within the range of the

"PTO Vehicle Speed Limit" that is programmed.