Actron Digital Multimeter CP7676 - Manual (Page 33)

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3. Disconnect wiring harness and vacuum
line from MAP sensor.
4. Connect jumper wire between Pin A on
wiring harness and sensor.
5. Connect another jumper wire between
Pin C on wiring harness and sensor.
6. Connect RED test lead to sensor Pin B.
7. Connect BLACK test lead to good
vehicle ground.
8. Make sure test leads and jumper wires
are not touching each other.
9. Connect a hand held vacuum pump to
vacuum port on MAP sensor.
10.Turn Ignition Key ON, but do not start
engine!
11. Turn multimeter rotary switch to...
• 20V range for DC type MAP sensors.
• 4 Cylinder RPM X 10 position for
Frequency type MAP sensors.
12.View reading on display.
DC Volts Type Sensor:
• Verify hand held vacuum pump is at 0 in.
of vacuum.
• Display reading should be approximately
3V or 5V depending on MAP sensor
manufacturer.
Frequency Type Sensor:
• Verify hand held vacuum pump is at 0 in.
of vacuum.
• Display reading should be approximately
4770RPM ± 5% for Ford MAP sensors
only.
• For other frequency type MAP sensors
refer to vehicle service manual for MAP
sensor specifications.
• It is O.K. if last two display digits change
slightly while vacuum is held constant.
• Remember to multiply display reading by
10 to get actual RPM.
• To convert RPM to Frequency or vice
versa, use the following equation:
Frequency =
RPM
30
{Equation Only Valid for Multimeter in 4
Cylinder RPM X 10 Position}
13.Operate Sensor.
• Slowly apply vacuum to MAP sensor -
Never exceed 20 in. of vacuum because
damage to MAP sensor may result.
• Display reading should decrease in
voltage or RPM as vacuum to MAP
sensor is increased.
• Refer to vehicle service manual for
charts relating voltage and frequency
drop to increasing engine vacuum.
• Use equation above for Frequency and
RPM conversions.
14.Test Results.
Good Sensor:
• Sensor output voltage or
frequency(RPM) are within manufactur-
ers specifications at 0 in. of vacuum.
• Sensor output voltage or
frequency(RPM) decrease with increas-
ing vacuum.
Bad Sensor:
• Sensor output voltage or
frequency(RPM) are not within
manufacturers specifications at 0 in. of
vacuum.
• Sensor output voltage or
frequency(RPM) do not change with
increasing vacuum.