Testing Map Or Bp/Map Sensors With Frequency Output - Fluke 88 V User Manual

Model 88 V
Users Manual
Testing MAP or BP/MAP Sensors with
Frequency Output
To use the Frequency function to check barometric
pressure/ manifold absolute pressure (BP/MAP) sensors:
1. Insert the test leads in the input terminals as shown
in Figure 10.
2. Set the rotary switch to
3. Connect the test lead clips to the circuit according to
the manufacturer's wiring diagrams.
Press G once to select frequency. Hz appears on
4.
the display. Press C repeatedly to step to the 6 V
range. "6" should appear at the right side of the
display. Use E to change trigger slope.
5. With the ignition KEY ON but the ENGINE OFF
(KOEO), pump the vacuum up.
6. Watch the frequency change on the display.
Compare the frequency at various vacuum readings
with the specifications in the vehicle's service
manual. At 0 inches of mercury, the frequency should
match specification for your altitude.
38
L
.
Note
Frequency measurements can be made on
voltage (V dc, V ac, or mV dc) or current inputs
(mA/A ac or dc). In automotive applications,
however, most Frequency measurements will be
made using the volts ac function.