How to test MAP sensor?

[DBuchheit]

Can anyone tell me the proper procedure for testing a MAP sensor in a 2001 CTD?



Thanks

 

[Alan Reagan]

It's almost impossible if not impossible to test this across the range. I don't have a service manual with me but believe that the voltage is around 4. 5 at sea level and goes to 2. 5 at 10,000 feet. I may be backwards in the voltages but my point it that you can only check it across the range with a hyperbaric (sp?) chamber to simulate air pressure at altitude. The only fault you would get is a code set to indicate voltage too high or voltage too low using a scan tool. One indicates the sensor is open and the other indicates it has shorted. The voltages at high/low altitude are given in the service manual if anyone has one handy.

 

[Little Bill]

There are some threads from a year ago that discuss the changes with the '01 map sensors. The outputs are different from pre-'01 units.



Unscrew sensor from manifold and connect to a regulated air supply. There are three electrical connections on the sensor; 5 volt supply, ground and 0-5 volt output signal. You can use a standalone power supply. I just inserted a pickup wire into the output connector and plugged back into the truck. The results are below and were verified by CannonBall.



You may set a code when you switch the ignition on to identify which pins do what. You will set an overboost code if you go much over 2. 5 volts



lbs volts

0 1. 068

5 1. 402

10 1. 732

15 2. 061

20 2. 391

25 2. 720

30 3. 050

 

[Alan Reagan]

Be careful not to come unplugged at any time from the connector or you'll set a code for "voltage too low".