Table of Contents
Advertisement
BASIC OPERATION AND FEATURES
SX TRANSISTOR CONTROL
automatically transitions back to the normal running
mode.
Section 2.1.5 Ramp Start
This feature provides maximum control torque to
restart a vehicle on an incline. The memory for this
function is the directional switch. When stopping on
an incline, the directional switch must be left in its
original or neutral position to allow the control to
initiate full power when restarted. The accelerator
potentiometer input will modulate ramp start current.
Section 2.1.6 On-Board Coil Drivers and Internal
Coil Suppression
A coil driver for the LINE contactor is on-board the
control card. This contactor must have a coil rated for
the vehicle battery volts.
Section 2.2 System Protective Override
Section 2.2.1 Static Return to Off (SRO)
This inherent safety feature of the control is designed
to prevent the driver from starting the vehicle with the
accelerator pedal depressed. If the pedal is
depressed when the key is turned on, the control will
not operate until the accelerator pedal is no longer
depressed.
Section 2.2.2 Accelerator Volts Hold Off
This feature checks the voltage level at the
accelerator input whenever the key switch is
activated. If, at start-up, the voltage is greater than
0.9 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 start-up and during running.
The control will not allow the line contactor to
close at start-up, or will drop it out during running,
if either the armature or field FET's are defective,
so as to cause uncontrolled truck movement.
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. 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 36-84 volts, and 75 percent of a
nominal battery voltage of 24 volts. Lower battery
voltage may cause the control to operate improperly,
however, the resulting PMT should open the Line
contactor, in the event of a failure.
Section 2.3 Diagnostics
The control detects the system's present operating
status and this status can be displayed to either the
Dash Display or the Handset.
Section 2.3.1 Status Codes
Section 2.3.1a Standard Status Codes
The SX control has a wide variety of Status Codes
that assist the service technician and operator in
trouble shooting the vehicle. If mis-operation of the
vehicle occurs, a status code will be displayed on the
Dash Display for vehicles so equipped, or be
available from the status code displayed when the
Handset is plugged into the "Y" plug of the logic card.
With the status code number, follow the procedures
outlined in DIAGNOSTIC STATUS CODES to
determine the problem and appropriate corrective
action.
Note: The Status Code Instruction Sheets do not
purport 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 2.3.1.b Stored Status Codes
This feature records the last 16 "Stored Status
Codes" that have caused a PMT controller shut down
Page 6
Updated Sept 2019
Advertisement
Table of Contents
Troubleshooting
