TEST 2: Making Sure The TPS Has 5 Volts
Like any other electrical component, the throttle position sensor needs power (voltage) to function.
In this test section, we're gonna' make sure that the grey (GRY) wire, of the TPS connector, is providing 5 Volts DC.
In the photo above, the GRY wire connects to the terminal labeled with the letter A.
These are the test steps:
- 1
Place your multimeter in Volts DC mode.
- 2
Disconnect the TPS from its electrical connector.
- 3
Turn the key on but don't start the engine.
- 4
With the red multimeter test lead (using the appropriate tool), gently probe the terminal labeled with the letter A.
Terminal A connects to the GRY wire of the connector. - 5
Connect the black multimeter test lead to the negative (-) battery terminal.
- 6
Your multimeter should read 4.5 to 5 Volts DC.
Let's analyze your test results:
CASE 1: The GRY wire is feeding the TPS with 5 Volts. This is the correct test result.
Now that you have confirmed that your Chevrolet Silverado or GMC Sierra's TPS is getting 5 Volts, the next step is to make sure it's getting Ground. Go to: TEST 3: Making Sure The TPS Has Ground.
CASE 2: The GRY wire IS NOT feeding the TPS with 5 Volts. Without these 5 Volts the TPS, on your Chevrolet Silverado or GMC Sierra, will not function.
These missing 5 Volts are usually the result of an open-circuit problem in the GRY wire between the TPS sensor's connector and the fuel injection computer's connector.
TEST 3: Making Sure The TPS Has Ground
So far your test results have confirmed 2 important things:
- The TPS is not producing a voltage signal that increases/decreases as you open/close the throttle plate (TEST 1).
- The TPS is getting 5 Volts on the GRY wire (TEST 2).
In this last test section, we're gonna' make sure that the black (BLK) wire, of the TPS connector, is providing the sensor with Ground.
NOTE: Ground is provided by the fuel injection computer of your Chevrolet Silverado (GMC Sierra). Be careful and don't connect this wire to battery 12 Volts or you'll fry the fuel injection computer. The multimeter voltage test I'm suggesting below is a safe way to test for the presence of Ground in the wire.
Let's get started:
- 1
Place your multimeter in Volts DC mode.
- 2
Disconnect the TPS from its electrical connector.
- 3
Turn the key on but don't start the engine.
- 4
With the black multimeter test lead (using the appropriate tool), gently probe the terminal labeled with the letter B.
Terminal B connects to the BLK wire of the connector. - 5
Connect the red multimeter test lead to the positive (+) battery terminal.
- 6
Your multimeter should read 10 to 12 Volts DC.
Let's analyze your test results:
CASE 1: The BLK wire is feeding Ground to the TPS. This is the correct test result.
You can correctly conclude that the TPS is defective if you have:
- Confirmed that the TPS voltage signal does not increase/decrease as you opened/closed the throttle plate (TEST 1).
- Confirmed that the TPS is getting 5 Volts (TEST 2).
- Confirmed, in this test section, that the TPS is getting Ground.
CASE 2: The BLK wire IS NOT feeding Ground to the TPS. Without Ground the TPS will not function.
This missing Ground is usually caused by an open-circuit problem in the BLK wire between the throttle position sensor's connector and the fuel injection computer's connector.
More Silverado, Sierra, Suburban, Tahoe, And Yukon Tutorials
You can find a complete list of V8 Silverado, Sierra, Suburban, Tahoe, and Yukon tutorials in this index:
Here's a small sample of the tutorials you'll find in the index:
- Resistance Specifications Of The TAC Electronic Throttle Body.
- How To Test The GM Accelerator Pedal Position (APP) Sensor 2.
- How To Test The MAF Sensor (GM 4.8L, 5.3L, 6.0L, 8.1L).
- Blown Head Gasket Test (GM 4.8L, 5.3L, 6.0L).
If this info saved the day, buy me a beer!
