BENDIX ET-2 ELECTRONIC THROTTLE Manual - Página 4

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6. Record the output voltage when the pedal is in the idle

position (V1). Then slowly depress the pedal. When

the ohm meter shows that the resistance has changed

from "overload" to about .003 ohms (or from .003 ohms

to "overload"), stop depressing the pedal. Record the

voltage (Vx) registered with the pedal in this position.

Then press the pedal to the full throttle position and

record the output voltage (V2).

7. Calculate the "switch point percentage" using the formula

below.

Switch point percentage = ((Vx-V1)/(V2-V1))*100

Vx = Output voltage when the switch changed

V1 = idle voltage

V2 = full throttle voltage

DIGITAL

VOLT/

POWER

OHM

SUPPLY

METER

(9-16 VDC)

RESISTOR

TEST LOAD

47,000 OHM

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FIGURE 7 - ET-2

TREADLE ELECTRICAL TEST

SCHEMATIC FOR THE CUMMINS CONNECTOR

8. The switch point percentage should be between 3% to

10%. If it is not with in this range adjust the

potentiometer by loosening the mounting screws and

turning the potentiometer within the range allowed by

the mounting holes. Repeat steps 1-7 again. If you can

not obtain the proper switch point percentage, replace

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with a new ET-2

treadle, available at your nearest

Bendix parts outlet.

9. After a successful test the vehicle may be returned to

service.

POTENTIOMETER

PC. NO. ON THIS

SURFACE

The following instructions are for a bench test for the

potentiometer used with Cummins engines.

10. Unplug the cable assembly from the potentiometer's

integral connector by lifting the lock tab and pulling the

connectors until they disengage. Inspect cable

assembly for loose terminals, frayed wires, corrosion,

wear, or physical damage. Check end-to-end electrical

continuity at terminals. NOTE: Potentiometer pin

locations will remain constant (see Figure 5). However,

cable assembly connector pin out may vary from engine

to engine.

11. Remove the ET-2

12. Secure the ET-2

such a way that it does not twist the unit.

13. Connect the potentiometer to the volt meter and power

supply as shown in Figure 5. NOTE: Power supply

can be a 12 VDC vehicle battery in good condition and

with known voltage output.

14. Verify that the closed throttle (idle) output voltage, as a

percentage of supply voltage, is within the limits listed

in Figure 2.

15. Depress the treadle to its full throttle position. The

output voltage, as a percentage of supply voltage, should

be within the limits listed in Figure 2. e.g. Testing a

Detroit Diesel ET-2

10 VDC. Full throttle = 9 VDC. 9/10 x 100 = 90%.

PIN C

16. Make several full applications and record idle position

GROUND

voltage each time. Verify that idle position voltage does

PIN B

not vary by more than .4% (.02 volts). If the ET-2

VOUT

(OUTPUT)

treadle does not operate within its specified ranges,

service the unit, or replace it with a new ET-2

PIN A

VREF

available at your nearest Bendix parts outlet.

(INPUT)

Test 3: For Cummins engines (with integrated switch

and sensor (ISS): For use only with the Cummins Celet

Plus and later editions of the ECU. This sensor can

not be used to replace the separate potentiometer &

idle validation switch. To do this a new ET-2

with the ISS must be purchased.

Test 1: Where the set resistance and voltage is shown

on a label. The Cummins potentiometer on the ET-2

treadle has an integral idle validation switch. It also has a

set resistance value marked on the cover, which needs to

be used to properly install the potentiometer. The drive

slot in the potentiometer should engage with the drive

tang at the end of the drive shaft. Next rotate the

potentiometer until the hole in the metal sleeve matches

the mounting holes on the actuator base. Loosely screw

the potentiometer in place but do not tighten. Connect

an ohmmeter to pins 3 (APS output) and 4 (APS ground)

as shown in Figure 8. Now the installer should read the

set resistance value marked on the label. Rotate the

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treadle from the vehicle.

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treadle to a smooth, flat surface in

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Treadle Potentiometer: Battery =

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treadle,

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treadle

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