TEST 1: Making Sure The TPS Is Getting 5 Volts
The first thing that we're gonna' do is to make sure that the TPS is getting 5 Volts DC from the fuel injection computer.
If 5 Volts are present, then the next step is to make sure that the TPS is getting Ground (TEST 2).
Although all of the TPS tests are done with the engine off, it's important that your Ford Escape or Mazda Tribute's engine be at normal operating temperature for the tests.
These are the test steps:
- 1
Once you have warmed up the engine, turn it off and remove any plastic covers that may be hiding the TPS from view and access.
- 2
If necessary, remove the air duct that connects the throttle body to the mass air flow sensor assembly.
- 3
Put your multimeter in Volts DC mode.
If you don't have a digital multimeter and need to buy one, see my recommendations here: Buying A Digital Multimeter For Automotive Diagnostic Testing. - 4
Disconnect the TPS from its electrical connector.
- 5
With the red multimeter test lead, and an appropriate tool, probe the wire labeled with the number 3 in the photo above.
- 6
Connect the black multimeter test lead to the negative (-) battery terminal.
- 7
Turn the key to its ON position but do not start the engine.
Your multimeter should read 4.5 to 5 Volts.
Let's take a look at what your test results mean:
CASE 1: The multimeter registered 4.5 to 5 Volts. This is the correct test result.
So far so good, since this confirms that the PCM is providing the correct voltage to the TPS. The next step is to test the Signal Return Circuit. For this test go to: TEST 2: Making Sure The TPS Is Getting Ground.
CASE 2: The multimeter DID NOT register 4.5 to 5 Volts. This test result lets you know that the fuel injection computer is NOT providing the voltage that the TPS needs to operate.
This missing voltage could be the result of an open-circuit problem in the wire or the PCM may be fried.
Altho' testing these two conditions are beyond the scope of this article, you have now eliminated the throttle position sensor (TPS) on your Ford vehicle as being the cause of the problem and/or the TPS diagnostic trouble code (DTC) lighting up the check engine light (CEL).
TEST 2: Making Sure The TPS Is Getting Ground
In this test step, you're gonna' verify that the PCM is or is not providing a Ground for the 5 Volts you verified that the TPS is receiving in TEST 1.
The wire that supplies Ground to the TPS, of your 2001-2007 3.0L Ford Escape (Mazda Tribute), is the one labeled with the number 1 in the photo above.
NOTE: The fuel injection computer is the one that supplies Ground to the TPS. Be careful and don't short the Ground wire to battery 12 Volts or you'll damage the computer. The multimeter voltage test suggested in the test steps is a safe way to test for the presence of Ground in the wire.
OK, let's start:
- 1
Place your multimeter in Volts DC mode.
- 2
Disconnect the TPS from its electrical connector.
- 3
Probe the wire labeled with the number 1 in the photo above, with the black multimeter test lead and the appropriate tool.
- 4
Connect the red multimeter test lead to the battery positive (+) terminal.
- 5
Turn the key to its ON position but don't start the engine.
The multimeter should display 10 to 12 Volts if Ground is present.
Let's take a look at what your test results mean:
CASE 1: The multimeter displayed 10 to 12 Volts. This is the correct test result and lets you know that the PCM is feeding a good Ground to the TP sensor.
The next step is to verify that the TP sensor is creating a good throttle position signal the PCM can use, go to: TEST 3: Testing The TP Signal.
CASE 2: The multimeter DID NOT display 10 to 12 Volts. Then the PCM is NOT supplying a Ground either because of an internal fault/problem or there's an open-circuit problem in the wire between the TPS and the PCM itself.
Altho' testing these two conditions are beyond the scope of this article, you have now eliminated the throttle position sensor (TPS) on your Ford vehicle as being the cause of the problem and/or the TPS diagnostic trouble code (DTC) lighting up the check engine light (CEL).