TEST 2: Making Sure The TPS Is Getting 5 Volts
The throttle position sensor receives 5 Volts from the violet with white stripe (VIO/WHT) wire of the sensor's 3-wire connector.
In the photo above, the terminal labeled with the number 1 is the terminal that connects to the VIO/WHT wire.
To make sure that these 5 Volts are present in the VIO/WHT wire, we'll do a simple multimeter voltage test.
NOTE: Avoid probing the front of the female terminal with your multimeter test lead. Use a back probe or a wire piercing probe instead. If you do probe the front of the terminal, do it very gently so that it won't get damaged.
Let's get testing:
- 1
Place your multimeter in Volts DC mode.
- 2
Disconnect the TPS from its electrical connector.
- 3
With the red multimeter test lead and an appropriate tool probe the VIO/WHT wire of the sensor's 3-wire connector.
- 4
Connect the black multimeter test lead to the negative (-) battery terminal.
- 5
Turn the key to its ON position but don't start the engine.
- 6
The multimeter should display 4.5 to 5 Volts.
Let's analyze your test result:
CASE 1: The VIO/WHT wire is supplying 4.5 to 5 Volts DC. This is the correct test result and confirms that the throttle position sensor is receiving 5 Volts DC from your mini-van's fuel injection computer.
Now, you need to make sure that Ground is present in the black with light blue stripe (BLK/LT BLU) wire. For this test go to: TEST 3: Making Sure The TPS Is Getting Ground.
CASE 2: The VIO/WHT wire IS NOT supplying 4.5 to 5 Volts DC. Without these 5 Volts, the throttle position sensor will not function.
The most likely reasons for these missing 5 Volts are:
- The VIO/WHT wire has open-circuit problem between the throttle position sensor's 3-wire connector and the fuel injection computer's connector.
- The MAP sensor has an internal short-circuit problem.
- The fuel injection computer may be fried (although a very rare thing to happen).
Altho' it's beyond the scope of this tutorial to test these conditions, you have now eliminated the throttle position sensor (TPS) on your 3.3L V6 Dodge Grand Caravan or 3.3L V6 Plymouth Grand Voyager as bad.
TEST 3: Making Sure The TPS Is Getting Ground
If you've reached this point, the previous 2 tests have confirmed that:
- The TPS signal voltage does not increase/decrease when you open/close the throttle plate.
- The VIO/WHT wire is supplying 5 Volts DC to the TPS sensor.
Now you need to confirm that Ground is being supplied to the TPS sensor by the black with light blue stripe (BLK/LT BLU) wire of the connector.
In the photo above, this BLK/LT BLU wire connects to the female terminal that's labeled with the number 3.
IMPORTANT: The fuel injection computer is the one that provides this Ground internally, so be careful and don't accidentally or intentionally apply battery power (12 Volts) to this wire or you'll fry the fuel injection computer. The voltage test, that's done with a multimeter and that I'm suggesting below, is a safe way to test for the presence of Ground in the wire.
OK, here are the test steps:
- 1
Place your multimeter in Volts DC mode.
- 2
Disconnect the TPS from its electrical connector.
- 3
With the black multimeter test lead and an appropriate tool probe the BLK/LT BLU wire.
- 4
Connect the red multimeter test lead to the positive (+) battery terminal.
- 5
Turn the key to its ON position but don't start the engine.
- 6
The multimeter should display 10 to 12 Volts.
Let's take a look at your test results:
CASE 1: The multimeter registered 10 to 12 Volts. This is the correct test result and confirms that the BLK/LT BLU wire is supplying Ground to the throttle position sensor.
You can conclude that the TPS sensor is bad and needs to be replaced only if you have:
- Confirmed that when you opened/closed the throttle plate, the TPS signal voltage did not increase/decrease (TEST 1).
- Confirmed that 5 Volts are being supplied to the TPS sensor (TEST 2).
- Confirmed that Ground is being supplied to the TPS sensor.
If you'd like to save some bucks on the TP sensor, consult my recommendations here: Where To Buy The TPS And Save.
CASE 2: The multimeter DID NOT register 10 to 12 Volts. This test result confirms that the BLK/LT BLU is not feeding the TPS sensor with Ground. Without Ground the throttle position sensor will not create its TPS signal.
The most likely reasons for this missing Ground are:
- The BLK/LT BLU wire has open-circuit problem between the TPS sensor's connector and the fuel injection computer's connector.
- The fuel injection computer may be fried (although a very rare thing to happen).
Altho' it's beyond the scope of this tutorial to test these conditions, you have now eliminated the throttle position sensor (TPS) on your 3.3L V6 Dodge Grand Caravan or 3.3L V6 Plymouth Grand Voyager as bad.
