The throttle position sensor (TPS) on your 1.5L Honda Civic is probably one of the easiest components of the fuel injection system to test. You can easily find out if it's bad or not in 2 simple multimeter tests. The cool thing is that you don't need a scan tool to do it.
In this tutorial I will show you how in a step-by-step way. Moreover, you don't need to remove the TPS assembly from the throttle body to test it.
Contents of this tutorial:
You can find this tutorial in Spanish here: Cómo Probar El Sensor TPS (1.5L Honda Civic) (at: autotecnico-online.com).
Symptoms Of A Bad Throttle Position Sensor
As I'm sure you're already aware, the throttle plate opens and closes as you step on or off the accelerator pedal. Its the TP sensor's job to report this throttle plate angle to your Civic's fuel injection computer.
This throttle plate angle signal is a voltage signal that increases from about 0.4 Volts DC to about 4.5 Volts DC at the throttle plate's wide open throttle (WOT) position.
Since the TPS is a critical sensor for the engine management, when it fails you'll see the following trouble code lighting up the check engine light on your 1.5L Civic's instrument cluster:
- Code 7: Throttle Position Sensor.
The TPS has 3 wire sticking out of its connector. 2 of those 3 wires supply it with power and Ground. The 3rd wire is the one that carries the throttle plate position signal back to the fuel injection computer. In the table below are the wire descriptions we need to know to be able to successfully test the TPS.
|TPS Circuits (1992, 1993, 1994, 1995 1.5L Honda Civic)|
|2||RED/BLU||Throttle Position Signal|
Where To Buy The TPS And Save
If you find, after testing the Civic's throttle position sensor, that it's fried; take a look at the links below. I think they'll save you some bucks:
NOTE: If you're not sure if the above TPS fit your particular 1.5L Civic don't worry. Once you get to the site, they'll make sure the sensor is the right one, if not, they'll find you the right one.
TEST 1: Testing The TPS Voltage Signal
OK, the first test is to verify that the TPS, on your 1.5L Civic, is producing a throttle plate position voltage signal that increases as you open the throttle plate and decreases as you close it.
If your Honda Civic's TP sensor is defective then its throttle plate voltage signal will stay fixed at a single voltage value.
To be a bit more specific, the voltage value your multimeter reports WILL NOT increase to about 4.5 Volts as you open the throttle plate NOR will it decrease to about 0.4 Volts as you release it.
If you don't have a multimeter and need to buy one, check out my recommendations here: Buying A Digital Multimeter For Automotive Diagnostic Testing (at: easyautodiagnostics.com).
IMPORTANT: You don't need to remove the TPS to bench test it, since it can be easily tested while it's still bolted in place on the throttle body. Also, you'll need to use a wire-piercing probe or a back-probe to measure the TP signal voltage. To see what a wire-piercing probe looks like, go here: Wire Piercing Probe.
You can see this test step performed in this YouTube video here: How To Test The TPS (1997, 1998, 1999, 2000, 2001 2.0L Honda CR-V) (NOTE: Although this video applies to the 1997-2001 2.0L Honda CR-V, the test procedure itself is the same for the 1993-2005 1.6L Honda Civic).
Here are the steps:
Set your multimeter to Volts DC mode.
Connect the red multimeter test lead to the middle wire of the sensor's connector. The middle wire connects to pin #2 in the illustration above and is the red with blue stripe (RED/BLU) wire.
Connect the black multimeter test lead on the battery negative (-) terminal.
Have your helper turn the key to the ON position, but don't start the engine (this will power up the TP sensor).
Your multimeter should report a voltage between 0.2 to 0.9 Volts DC.
If your multimeter doesn't, don't worry about it just yet, continue with the other steps.
Now, slowly open the throttle plate (by hand and from the engine compartment) while you observe the change in voltage numbers on your multimeter.
For this test result to be accurate, you need to open the throttle by hand and not from inside the vehicle.
As the throttle plate opens, the voltage numbers will increase.
This increase in voltage should be smooth and without any gaps or skips. Once the throttle is wide open, your multimeter should read somewhere between 3.5 to 4.5 Volts DC.
Now, slowly close the throttle plate.
As the throttle is closing, you should see the voltage decrease smoothly and without any gaps or skips, to the exact same voltage you noticed in step 4.
Have your helper lightly tap on the throttle position sensor with the handle of a screw-driver (or something similar, and I want to emphasize the words ‘lightly tap’) as you slowly open and close the throttle and observe the multimeter.
If the TPS is bad, the tapping will cause the voltage numbers to skip or go blank.
If the TPS is OK, the tapping will have no effect on the voltage numbers.
Repeat step 9 several times to make sure of your multimeter test results.
Let's take a look at your test results:
CASE 1: The throttle angle voltage increased and decreased as you opened and closed the throttle plate. This test result confirms that the TP sensor is OK and not defective.
CASE 2: The throttle angle voltage DID NOT increase (and/or decrease) as you opened and closed the throttle plate. This test result confirms the throttle position sensor trouble code lighting up the check engine light on your 1.5L Honda Civic.
If I where in your shoes and to be sure that the TPS has truly failed, I would still make sure that the TP sensor is getting both power and Ground. To check for power on the LT GRN wire, go to: TEST 2: Verifying Throttle Position Sensor Has 5 Volts And Ground.
CASE 3: The multimeter DID NOT register any voltage. This test result doesn't condemn the TP sensor as defective just yet. Why? Because the TP sensor may be missing either power or Ground.
So the next step is to check that the TP sensor is getting power and Ground, go to: TEST 2: Verifying Throttle Position Sensor Has 5 Volts And Ground.