Actron AutoTroubleShooter CP7677 User Manual download pdf (Page 30)

30

Position Type Sensors

Position sensors are potentiometers or

a type of variable resistor. They are

used by the computer to determine po-

sition and direction of movement of a

mechanical device. Typical position sen-

sor applications are throttle position

sensors, EGR valve position sensors,

and vane air flow sensors.

Test Procedure (see Fig. 33):

• If multimeter overranges on larg-

est range, then sensor is an open

circuit and is defective.

7. Move RED test lead to sensor SIG-

NAL pin.

• Refer to vehicle service manual for

location of sensor SIGNAL pin.

8. Operate Sensor.

Fig. 33

1. Insert BLACK test lead into COM

test lead jack.

2. Insert RED test lead into

test lead jack.

3. Disconnect wiring harness from

sensor.

4. Connect Test Leads.

• Connect RED test lead to sensor

POWER pin.

• Connect BLACK test lead to sen-

sor GROUND pin.

• Refer to vehicle service manual for

location of sensor POWER and

GROUND pins.

5. Turn multimeter rotary switch to

20K

Ω range.

6. View and record reading on dis-

play.

• Display should read some resis-

tance value.

• If multimeter is overranging, adjust

the range accordingly. (See Set-

ting the Range on page 6.)

Typical Toyota Throttle

Position Sensor

Red

Black

POWER GROUND

SIGNAL IDLE SWITCH

• To test these switches, follow the

Testing Switches test procedure

on page 13.

• When you are told to operate

switch, then move throttle linkage.

Vane Air Flow Sensor:

• Slowly open vane “door” from

closed to open by pushing on it

with a pencil or similar object. This

will not harm sensor.

• Depending on hook-up, the dis-

play reading will either

increase or

decrease in resistance.

• The display reading should either

start at or end at the approximate

resistance value measured in Step

6.

• Some vane air flow sensors have

an idle switch and an intake air

temperature sensor in addition to a

potentiometer.

• To test idle switch see Testing

Switches on page 13.

• When you are told to operate

switch, then open vane “door”.

Throttle Position Sensor:

• Slowly move throttle linkage

from closed to wide open posi-

tion.

• Depending on hook-up, the dis-

play reading will either

increase

or decrease in resistance.

• The display reading should ei-

ther

start at or end at the ap-

proximate resistance value

measured in Step 6.

• Some throttle position sensors

have an Idle or Wide Open

Throttle (WOT) switch in addi-

tion to a potentiometer.

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