The manifold absolute pressure (MAP) sensor can be accurately tested with a multimeter and a vacuum pump and in this article I'll show you how.
When the MAP sensor goes BAD, you'll usually see one of the following diagnostic trouble codes stored in your Dodge's computer's memory: P0106, P0107, or P0108. If this is the case, this is the article for you.
NOTE: This tutorial only covers the MAP sensor test on 1997 thru' 2003 Ram pickups/vans. For the MAP sensor test on 1994 thru' 1996 Ram pickups/vans, see the following tutorial:
This article is broken up into several different parts and so to help you navigate it a little easier, here are its contents at a quick glance:
The following wiring diagram article may come in handy:
You can find this tutorial in Spanish here: Cómo Probar el Sensor MAP (Dodge 3.9L, 5.2L, 5.9L) (at: autotecnico-online.com).
When the manifold absolute pressure (MAP) sensor fails, the check engine light (CEL) will turn on and you'll see one of the following diagnostic trouble codes:
Besides the diagnostic trouble codes, your Dodge pickup, van or SUV will experience one or several of the following symptoms:
It's rare for the MAP sensor to go BAD but it doesn't mean they don't. What usually happens is that some other condition (affecting engine performance) fools the PCM (Powertrain Control Module = fuel injection computer) into thinking that the MAP sensor is BAD... so it's always a good idea to test it before replacing it.
In my experience, the absolute best way to test the MAP sensor is to bench test it (and this is how I'm gonna' show you how to tested in this article). By bench testing it, you can eliminate the other possibles that may be fooling the MAP sensor into sending a BAD signal to the PCM.
If after doing the MAP sensor test and the MAP sensor is good, then take a look at the section: MAP Sensor Code Won't Go Away.
The fuel system on your 3.9L, 5.2L, 5.9L is a ‘Speed Density’ type... which in lay man's terms means that it doesn't use a mass air flow (MAF) sensor to determine the amount of air that enters the engine.
In a ‘Speed Density’ fuel system, the PCM relies heavily on MAP sensor and engine RPM input to find out how much air the engine is breathing. Once it has calculated the amount of incoming air, it can then calculate the correct amount of fuel to inject (among several things).
OK, in a nutshell, cause I know you're probably itching to get testing, when you turn the key and crank the engine:
Since the MAP sensor plays such a critical role in the performance and efficient operation of the engine in your pickup (van, SUV)... when it goes BAD, your vehicle is gonna' be in a world of hurt.
“When I was born I was so ugly the doctor slapped my mother.”