
BASIC OPERATION AND FEATURES
SX TRANSISTOR CONTROL | Page 8 |
Section 2.1.7 On-Board Coil Drivers & Internal Coil Suppression
Coil drivers for the LINE and SP contactors
are
Section 2.2 System Protective Override
Section 2.2.1 Static Return to Off (SRO)
This inherent feature of the control is designed to require the driver to return the directional lever to the neutral position anytime he leaves the vehicle and returns. Additionally, if the seat switch or key switch is opened, the control shuts off and cannot be restarted until the directional lever is returned to neutral. A time delay of approximately 2 seconds is built into the seat switch input to allow momentary opening of the seat switch, if a bump is encountered.
Section 2.2.2 Accelerator Volts Hold Off
This feature checks the voltage level at the accelerator input whenever the key switch or seat switch is activated. If, at start up, the voltage is less than 3.0 volts, the control will not operate. This feature assures that the control is calling for low speed operation at start up.
Section 2.2.3 Pulse Monitor Trip (PMT)
The PMT design contains three features which shut down, or lock out, control operation if a fault conditions occurs that would cause a disruption of normal vehicle operation:
•Look ahead
•Look again
•Automatic look again and reset
The PMT circuit will not allow the control to start under the following conditions:
•The control monitors both armature and field FET's at
•The control will not allow the line contactor to close at
Section 2.2.4 Thermal Protector (TP)
This temperature sensitive device is internal to the power transistor (Q1) module. If the transistor's temperature begins to exceed the design limits, the thermal protector will lower the maximum current limit, and maintain the transistors within their temperature limits. Even at a reduced current limit, the vehicle will normally be able to
reach sufficient speed. As the control cools, the thermal protector will automatically reset, returning the control to full power.
Section 2.2.5 Low Voltage
Batteries under load, particularly if undersized or more than 80 percent discharged, will produce low voltages at the control terminals. The SX control is designed for use down to 50 percent of a nominal battery voltage of
Section 2.3 Diagnostics
Section 2.3.1 Systems Diagnostics
The control detects the system's present operating status and can be displayed to either the Dash Display or the Handset. There are currently over 70 status codes that are available with SX systems using Traction and Pump controls and Truck Management Module (TMM). Along with the status code display from the TMM, the SX control is capable of reducing the current to the motor, alerting the operator of a critical fault condition.
Section 2.3.2 Status Codes
Section 2.3.2a Standard Status Codes
The SX traction control has over 30 Status Codes that assist the service technician and operator in trouble shooting the vehicle. If
With the status code number, follow the procedures outlined in DIAGNOSTIC STATUS CODES to determine the problem and a solution.
Note: The Status Code Instruction Sheets do not claim to cover all possible causes of a display of a "status code ". They do provide instructions for checking the most direct inputs that can cause status codes to appear.
Section 2.3.2.b Stored Status Codes
This feature records the last 16 "Stored Status Codes" that have caused a PMT controller shut down and/or disrupted normal vehicle operation. (PMT type faults are reset by cycling the key switch). These status codes, along with the corresponding BDI and hourmeter readings, can be accessed with the Handset, or by using the RS 232 communications port and dumping the information to a Personal Computer terminal.
January 2000