TEST 2: Verifying Throttle Position Sensor Has Power
The throttle position sensor on your 3.0L Montero needs power (and Ground) to function. So, in this test step we'll check that the wire that connects to TPS connector pin #4 has 5 Volts DC with the Key in the On position.
Alright, these are the test steps:
Place your multimeter's dial in Volts DC mode and turn the key on but don't start the engine.
This will power up the TP sensor's connector.
Check the TPS connector terminal that corresponds to pin #4, of the TPS connector, with the red multimeter test lead.
IMPORTANT Be careful when probing the metal terminal of the TPS connector. Damaging the terminal will require that you replace the connector. Use a back probe or a wire piercing probe instead of probing the front of the connector.
Connect the black multimeter test lead to the negative (-) battery terminal.
When you've set up the test, have a helper turn the key on, but don't crank or start the engine.
Your multimeter should display 4.5 to 5 Volts on its screen.
Let's examine your multimeter test result:
CASE 1: Your multimeter registered 4.5 to 5 Volts. So far so good since this tells you that the throttle position sensor (TPS) is getting power from the powertrain control module (PCM).
The next and last test, is to make sure that the throttle position sensor is getting Ground (from the PCM too). For this test, go to: TEST 3: Verifying Throttle Position Sensor Has Ground.
CASE 2: Your multimeter DID NOT register 4.5 to 5 Volts. Double check all of your connections and repeat the test.
If your multimeter still doesn't register the 4.5 to 5 Volts DC, then this test result tells you that the TPS itself is not at fault (and thus not causing the TPS trouble code). Without power, the TPS can't create a throttle angle voltage signal. Although beyond the scope of this tutorial, your next step is to diagnose and restore this missing power.
TEST 3: Verifying Throttle Position Sensor Has Ground
So far, you have confirmed that the TPS is not creating the correct throttle angle voltage signal (based on throttle plate angle) and that it's being fed with 5 Volts DC.
In this last test step we're gonna' see if the TPS is being fed with Ground. If Ground is present, then based on your previous test results, you can conclude that the TPS itself is bad.
IMPORTANT: The TPS is fed Ground directly/internally by your Montero's PCM. Be careful and don't short this wire to battery voltage or you'll fry your Montero's PCM.
OK, here are the test steps:
Set your multimeter to Volts DC mode.
Probe the TPS connector wire that connects to the TP sensor's pin #1 with the black multimeter test lead. The wire that connects to pin #1 of the connector is the BLK wire.
Be careful not to damage the terminal if you probe it on the front of the connector. If possible, you should use a back probe or a wire-piercing probe to check this circuit.
Now, with the red multimeter test lead, probe the battery positive (+) terminal.
Turn the Key to its ON position but don't start the engine. This will power up the PCM.
Your multimeter will display 10 to 12 Volts if the BLK wire is feeding the TPS with Ground.
Let's examine your multimeter test result:
CASE 1: The multimeter showed 10 to 12 Volts. This is the correct test result and this tells you that the throttle position sensor, on your Mitsubishi, is being fed with Ground from the PCM.
All three test have confirmed that:
- The TP sensor is not providing a varying voltage signal when manually opening the throttle plate.
- The TP sensor is being fed 5 Volts DC.
- The TP sensor is being fed Ground.
Therefore, you can conclude that the throttle position sensor is bad and needs to be replaced (and that this will solve the TP sensor code lighting up the check engine light).
CASE 2: The multimeter DID NOT show 10 to 12 Volts. Double check that you're testing the correct TP sensor harness terminal wire and repeat the test.
If your multimeter still doesn't show the indicated voltage, then we can conclude that there's an open in the wire between the TP sensor harness connector and the PCM's harness connector. In the extreme of cases, the PCM has an internal problem (although this is very rare).
Although testing these two conditions are beyond the scope of this article, you have now eliminated the throttle position sensor (TPS) on your 3.0L Mitsubishi as being the cause of the problem and/or the TP sensor diagnostic trouble code (DTC) lighting up the check engine light (CEL).
Where To Buy Your TP Sensor And Save
Where can you buy the TP sensor for your 3.0L Mitsubishi Montero? You can buy it at your local auto parts store, but it's gonna' cost a whole lot more. I suggest taking a look at the price of the TP sensor in the following links and compare:
Not sure if the above TP sensor fits your particular 3.0L Mitsubishi? Don't worry, once you get to the site, they'll make sure it fits by asking you the particulars of your vehicle. If it doesn't fit, they'll find you the right one.
If this info really saved the day, buy me a beer!