MAP Sensor testing.
Thread Starter
|
Junior User
Joined: Sep 2007
Posts: 81
Likes: 0
MAP Sensor testing.
Does any one know what the voltage or frequency should be for the return signal for the MAP sensor. I have my 5v reference, and my map sensor frequecy from the middle pin, but I have almost no voltage on the last pin(signal return). Any ideas would be helpful and greatly appreciated.
Lead Driver
Joined: Nov 2002
Posts: 9,557
Likes: 44
From: Concord, NC
Signal return is nothing more than the computer's own ground circuit. There should be little to no voltage between this wire and ground. The signal return line should be your zero volt reference point when testing sensors instead of using battery ground.
Post Fiend
Joined: Oct 2003
Posts: 6,214
Likes: 13
From: New Jersey
Fleet Owner
Joined: Aug 2005
Posts: 23,667
Likes: 301
From: Easton,Ks
On Ford applications, a multimeter that can read
frequency is normally required to check the sensor’s
output. But you can also use an ordinary tachometer
because a tach can display a frequency signal.
Here’s the procedure:
1 Set the tachometer to the four-cylinder scale
(regardless of how many cylinders the engine has).
2 Connect one tachometer lead to the middle terminal
on the MAP sensor and the other tachometer test
lead to ground.
Connect the two jumper cables the same as before,
attaching each end terminal on the sensor to its
respective wire in the wiring connector.
4 If you want to measure engine vacuum so you can
correlate it to a specific frequency reading, connect
a vacuum gauge to a source of manifold vacuum
on the engine, or tee the gauge into the MAP
sensor hose.
5 Turn the ignition ON and note the initial reading.
The reading on the tachometer should be about
454 to 464 at sea level, which corresponds to a
frequency output of 152 to 155 Hz.
6 Start the engine and check the reading again.
If the MAP sensor is functioning properly, the
reading should drop to about 290 to 330 on the
tachometer, which corresponds to a frequency
output of about 93 to 98 Hz. No change would
indicate a defective sensor or leaky or plugged
vacuum hose.
frequency is normally required to check the sensor’s
output. But you can also use an ordinary tachometer
because a tach can display a frequency signal.
Here’s the procedure:
1 Set the tachometer to the four-cylinder scale
(regardless of how many cylinders the engine has).
2 Connect one tachometer lead to the middle terminal
on the MAP sensor and the other tachometer test
lead to ground.
Connect the two jumper cables the same as before,
attaching each end terminal on the sensor to its
respective wire in the wiring connector.
4 If you want to measure engine vacuum so you can
correlate it to a specific frequency reading, connect
a vacuum gauge to a source of manifold vacuum
on the engine, or tee the gauge into the MAP
sensor hose.
5 Turn the ignition ON and note the initial reading.
The reading on the tachometer should be about
454 to 464 at sea level, which corresponds to a
frequency output of 152 to 155 Hz.
6 Start the engine and check the reading again.
If the MAP sensor is functioning properly, the
reading should drop to about 290 to 330 on the
tachometer, which corresponds to a frequency
output of about 93 to 98 Hz. No change would
indicate a defective sensor or leaky or plugged
vacuum hose.
Last edited by subford; Nov 14, 2007 at 07:06 AM.
Lead Driver
Joined: Nov 2002
Posts: 9,557
Likes: 44
From: Concord, NC
He's got the frequency on the middle pin (sensor output) already...
The signal return is not supposed to have any voltage or frequency by itself, since it is the sensor ground or zero volt circuit.
The signal return is not supposed to have any voltage or frequency by itself, since it is the sensor ground or zero volt circuit.
Last edited by EPNCSU2006; Nov 14, 2007 at 05:25 PM.
Thread
Thread Starter
Forum
Replies
Last Post
Mountain54
1987 - 1996 F150 & Larger F-Series Trucks
6
Mar 7, 2017 04:38 PM
