2
As the driver depresses the treadle, the electronic treadle
output voltage increases (see Figure 3). The potentiometer
allows an increased amount of its supply voltage to return to
the engine control unit, which in turn increases the engine’s
speed.
In the full, or “Open Throttle” position, the driver has
depressed the treadle to its furthest possible point. This is
the state of least potentiometer resistance. The electronic
treadle returns the maximum percentage of supply voltage
to the engine control unit (see Figure 2).
PREVENTIVE MAINTENANCE
Important: Review the warranty policy before performing
any intrusive maintenance procedures. An extended warranty
may be voided if intrusive maintenance is performed during
this period.
Because no two vehicles operate under identical conditions,
maintenance intervals will vary. Experience is a valuable guide
in determining the best maintenance interval for a vehicle.
GENERAL
Important: Visually check for physical damage to the
electronic treadle such as broken or missing parts. Actuate
the pedal five times from stop to stop, noting any binding or
soft pedal response.
Important Note: DO NOT DISASSEMBLE THE ACTUATOR
BODY. Replace the ET-S
™
or ET-S2
™
treadle if there is
any binding, soft pedal actuation or if the nylon washers or
retaining rings indicated in Figure 4 are cracked or have
signs of deterioration.
Perform the inspections presented at the prescribed interval.
If the electronic treadle fails to function as described, it should
be repaired or replaced with a new or genuine Bendix remanu-
factured unit, available at any authorized parts outlet.
Every 3 months, or 25,000 miles, or 900 operating hours:
1. Remove any accumulated contaminants and visually
inspect the exterior of the electronic treadle assembly
for physical damage or excessive corrosion.
2. Inspect electrical connections and cable assembly for
signs of corrosion, wear, or physical damage. Replace
as necessary.
3. Inspect treadle spring, sleeve bearing, nylon washer,
rubber treadle cover (ET-S
™
treadle only) and retaining
ring for cracks or deterioration. Replace as necessary.
ET-S
™
& ET-S2
™
TREADLE REMOVAL
1. Park the vehicle on a level surface and block the wheels.
2. Drain the air pressure from all vehicle reservoirs.
3. Disconnect the cable assembly of the potentiometer.
Lift the lock tab and pull the connectors until they
disengage.
4. Remove the electronic treadle from the vehicle, set aside
the mounting hardware for reassembly.
DISASSEMBLY
Please note that the internal mechanism of the ET-S
™
and
ET-S2
™
treadle are not field-serviceable and therefore
individual parts or parts kits are not available for these
components. Disassembly may lead to malfunction of the
ET-S
™
or ET-S2
™
treadle.
The following instructions cover the maintenance and
replacement of the potentiometer and treadle (with its
bearing, spring etc.) only. The instructions provided with
those items should be followed in lieu of the steps presented
here. There are no other field-serviceable parts.
As the potentiometer rotates, its resistance changes. This
way, the potentiometer can react to the driver’s request for
engine power through the ET-S
™
or ET-S2
™
treadle by
changing resistance. The resulting change of voltage is
sensed by the electronic engine controller.
The electronic treadle receives its supply voltage from the
engine control unit. If the driver does not request engine
power, the treadle is in the idle position. This condition is
also referred to as “Closed Throttle.” In this state, the
potentiometer returns the minimum percentage of supply
voltage to the engine control unit (see Figure 2).
RETAINING
RINGS
MOUNTING PLATE
FIGURE 4 - TOP SECTIONAL VIEW
CAM FOLLOWER
DRIVE SHAFT
POTENTIOMETER
NYLON
WASHERS
