TEST 2: Verifying The MAP Is Getting Power
If in TEST 1 the MAP sensor DID NOT produce a decrease/increase in the MAP signal (as you applied/released vacuum), then there's a good chance that power or Ground is not being fed to the sensor.
In this test section, we're gonna' check that power is available to the MAP sensor by doing a simple multimeter voltage test.
The MAP terminal labeled with the number 1, in the illustration above, is the one that gets power from the MAP sensor connector's violet with white stripe (VIO/WHT) wire (on 2000 4.7L Durango) or the orange (ORG) wire on all others.
Alright, this is what you'll need to do:
Place your multimeter in Volts DC mode turn the ignition key to its On position. but don't crank or start the engine.
Probe the MAP sensor connector's VIO/WHT (or ORG) wire with the red multimeter test lead. The VIO/WHT (or ORG) wire is the one that connects to the MAP terminal labeled with the number 1, in the illustration above.
You can test for these 5 Volts with the MAP sensor's electrical connector connected to the MAP sensor or not, just avoid probing the front of the connector.
Ground the black multimeter test lead on the battery's negative (-) post.
Your multimeter should show you 4.5 to 5 Volts DC if the VIO/WHT wire is feeding the MAP sensor with power.
OK, now that the testing part is done, let's take a look at what your results mean:
CASE 1: Terminal #1, of the MAP sensor connector, is getting 5 Volts DC. This is the correct result and it's starting to look like the MAP sensor is bad but you still need to check that the MAP sensor is getting Ground. For the Ground test, go to: TEST 3: Verifying The MAP Is Getting Ground.
CASE 2: Terminal #1, of the MAP sensor, IS NOT getting 5 Volts DC. This results lets you know that the MAP sensor is not bad, since without these 5 Volts DC, the MAP sensor can not function.
Although it's beyond the scope of this article to troubleshoot the cause of these missing 5 Volts, you have now eliminated the MAP sensor as bad. Resolving the issue that is keeping these 5 Volts from being supplied will solve the MAP sensor issue on your 4.7L Dakota pick up or 4.7L Durango SUV.
TEST 3: Verifying The MAP Is Getting Ground
So far, you have confirmed that on your 4.7L Dodge Durango (4.7L Dakota):
- A MAP sensor trouble code lighting up the check engine light (P0107 or P0108).
- The MAP sensor is not creating a decreasing/increasing MAP voltage signal (TEST 1).
- The MAP sensor is getting power (TEST 2).
For our last test, we need to make sure that the MAP sensor has a good path to Ground. To verify this Ground... we'll do another simple multimeter voltage test.
IMPORTANT: The BLK/LT BLU wire, that feeds the MAP sensor with ground, connects directly to the PCM. Be very careful and don't short this wire to battery power (12 Volts), or you WILL FRY the PCM.
Alright, this is what you'll need to do:
Place your multimeter in Volts DC mode and turn the ignition key to its On position but don't crank or start the engine.
Probe the MAP sensor connector's BLK/LT BLU wire with the black multimeter test lead.
It doesn't matter if you probe this circuit (wire) with the connector connected to the MAP sensor or not, but do not probe the front of the connector (if you decide to unplug the connector to test for this path to Ground).
Connect your multimeter's RED test lead to the battery's positive (+) post.
Your multimeter should show you 10 to 12 Volts DC if the BLK/LT BLU wire is feeding the MAP sensor with ground.
OK, let's take a look at what your results mean:
CASE 1: The multimeter registered 12 Volts. This is the normal result and it means that the MAP sensor is fried and needs to be replaced.
Here's why: In MAP TEST 1 and 2, you verified that the MAP sensor is not producing the correct values (when you applied vacuum) and that it does have power. Since in this test step you have confirmed that the MAP sensor does have a solid path to Ground, these results, interpreted together, indicate that the MAP sensor is bad.
If you'd like to buy the original AC Delco MAP sensor and save, take a look at the section: Where To Buy The MAP Sensor And Save.
CASE 2: The multimeter DID NOT register 12 Volts. Double check your multimeter connections and repeat the test... if your multimeter results still do not indicate 12 Volts, then the MAP is not fried and not the cause of the MAP diagnostic trouble code (DTC) issue.
Here's why: Without a good path to Ground, that the PCM provides internally, the MAP sensor will not work. With this test result, you have eliminated the MAP sensor as bad.