The fastest and the most accurate way to test the manifold absolute pressure (MAP) sensor on your 3.0L equipped Chrysler is to bench-test it with a multimeter.
In this tutorial I'll show you how in a step-by-step way so that you can find out if the MAP sensor is bad (or not).
This tutorial will also help you diagnose OBD I trouble code: Code 14: MAP Sensor Voltage High/Low.
Contents of this tutorial:
MAP Sensor Diagnostic Essentials
What are the symptoms of a bad MAP sensor? Since the MAP sensor is a critical component of the engine management system in your car or mini-van when it fails, the most obvious symptom is the check engine light (CEL) shining nice and bright on your instrument cluster and the following trouble code registered in the PCM's memory:
- Code 14: Manifold Absolute Pressure (MAP) Circuit Low Voltage.
- Code 14: Manifold Absolute Pressure (MAP) Circuit High Voltage.
You'll also see one or more of the following:
- Bad gas mileage.
- Won't pass the emissions test.
- Black smoke coming out the tail pipe when the engine in your 3.0L Chrysler car or mini-van is running.
- Your car or mini-van will crank but not start.
- Longer than normal cranking time before the engine starts.
- Engine idles very rough and may stall.
What tools do I need? The most important tool that you'll need is a multimeter.
The following tools are not a must to test the MAP sensor, but do come in handy:
- A vacuum pump.
- The vacuum pump is not an absolute must, since you can use the good ole lungs to apply vacuum to the sensor in TEST 1 of this tutorial.
- If you don't have one and/or need to buy one, this is the one that I recommend and you can buy it here: MV8000 Automotive Tune-up and Brake Bleeding Kit.
- Wire piercing probe.
- Although this tool is not an absolute must, if you do buy one, you'll realize just how easy it makes testing the voltages inside the wires.
- If you need to see what this tool looks like, you can see it here: Wire Piercing Probe.
What does the MAP sensor do? The MAP sensor's job is to continually measure the pressure (vacuum) inside the intake manifold as the engine in your Chrysler runs and send this info the your car or mini-van's fuel injection computer.
The fuel injection computer then uses the MAP sensor input, along with the inputs of the crank sensor, throttle position sensor (TPS) and intake air temp sensor to calculate the amount of air entering the engine, which it then uses to calculate the correct amount of fuel to inject into the engine (among several things).
The MAP sensor needs 3 inputs to be able to measure the amount of vacuum inside the intake manifold:
- 5 Volts (power).
As you already know, the MAP sensor's harness connector has 3 wires coming out of it. Each one provides a specific signal type. Here's a brief description of what each wire does:
|3.0L Chrysler MAP Circuits
(1991, 1992, 1993, 1994, 1995)
|1||BLK/LT BLU||Sensor Ground|
|2||DK GRN/RED||MAP Voltage Signal|
|3||VIO/WHT (or VIO)||5 Volts|
Diagnosing The 3.0L Chrysler MAP Sensor
Testing the MAP sensor on your 3.0L equipped Chrysler car or mini-van involves 3 specific tests, these are:
- The first test is to see if the MAP sensor is creating a signal as you manually apply vacuum with a vacuum pump (or the good ole lungs).
- The second test is to make sure that the MAP sensor is getting fed power (5 Volts) on the .
- The third test and last test involves checking that the MAP sensor is getting Ground.