How To Test The Throttle Valve (TV) Switch (2.6L Isuzu)

The throttle position sensor (TPS) is called the Wide Open Throttle Switch or the Throttle Valve Switch by the Isuzu service literature and in this tutorial, I'll show you how to test it.

You can find this tutorial in Spanish here: Cómo Probar El Sensor TPS (2.6L Isuzu Amigo, Pick Up, Rodeo) (at: autotecnico-online.com).

Symptoms Of Bad Throttle Valve Switch

Since the Isuzu's covered by this tutorial are OBD I equipped, a failed throttle position sensor (throttle valve switch) will set a diagnostic trouble code (DTC) and light up the check engine light on your 2.6L Isuzu Rodeo (Pick Up, Amigo).

Depending on the type of failure of the throttle valve switch, you'll see:

• Trouble codes:
  • Trouble Code 21: Throttle Valve Switch (Idle and WOT).
  • Trouble Code 43: Throttle Valve Switch (Idle Position).
  • Trouble Code 65: Throttle Valve Switch (Full Throttle).
• High idle.
• Rough idle.

Testing the throttle valve switch and/or adjusting it is a pretty easy affair. I'll explain how in the next sub-headings and pages.

Where To Buy The Throttle Valve Switch And Save

Check out the following links and comparison shop the throttle valve switch on your 2.6L Isuzu Amigo, Rodeo or Pick up (Honda Passport):

Not sure if the above throttle valve switch fits your particular 2.6L Isuzu Pick Up (Amigo, Rodeo)? Don't worry, once you click on the links and arrive on the site, they'll make sure it fits! If it doesn't, they'll find you the right one.

TEST 1: Making Sure The WOT Switch Is Getting Power

The first order of business, is to check the basics. So, we'll check/confirm that the throttle valve switch is getting power.

This power is in the form of battery voltage (10 to 12 Volts DC) and is provided by the middle wire of the throttle valve switch.

The illustration above is a representation of the front view of the throttle valve switch's connector. To be a bit more specific, the front view is the view that shows the metal terminals of the connector.

We'll use a multimeter for the test:

Alright, here are the steps:

1. 1

   Disconnect the throttle valve switch from its engine wiring harness connector and set your multimeter to Volts DC mode.

2. 2

   With the red multimeter test lead, probe the middle wire's terminal.
   
   NOTE: Probe the terminal gently and without a lot of pressure/force or you'll damage the terminal.

3. 3

   Ground the multimeter's black test lead on the battery's negative post or a clean/rust free spot on the engine.

4. 4

   The multimeter should register 10-12 Volts DC with the key in the ON position.

Let's take a look at what your test results mean:

CASE 1: The throttle valve switch is being fed power. So far so good. This test result confirms that the throttle valve switch is getting power.

Your next test is to check the continuity of the idle circuit and the wide open throttle circuit (inside the throttle valve switch). For the first of these two tests, go to: TEST 2: Testing The Continuity Of The Idle Circuit.

CASE 2: The throttle valve switch IS NOT being fed power. Double check your multimeter connections and retest. If still no voltage then you've found the problem causing the TV switch trouble code.

Finding and repairing the cause of this missing voltage will get the throttle valve switch back to work and solve the trouble code.

TEST 2: Testing The Continuity Of The Idle Circuit

Continuity should exist between two specific pins of the throttle valve (TV) switch when the throttle plate is closed (and if the throttle valve switch is working correctly and adjusted correctly).

Once the throttle plate opens (like when you step on the accelerator pedal), this circuit opens and loses continuity.

When this doesn't happen (either because the TV switch is bad or misadjusted), the fuel injection computer, on your 2.6L Isuzu Rodeo (Amigo, Pick Up), will usually set a trouble code 43: Throttle Valve Switch (Idle Position).

So, in this second test, we're gonna' check this 'idle' circuit with a multimeter in Ohms mode.

OK, these are the test steps:

1. 1

   Disconnect the throttle valve switch from its connector.
   
   NOTE: Use the illustration above to identify the correct pins to test on the throttle valve switch itself.

2. 2

   Set your multimeter to Ohms (Ω) mode and make sure that the throttle plate, in the throttle boy, is in the closed position.

3. 3

   With the throttle plate closed, measure the resistance across pin #1 and pin #2 of the throttle valve (TV) switch as shown in the illustration above.
   
   Your multimeter should show continuity (usually 5 Ohms or less).

4. 4

   Open the throttle plate to its fully open position and measure the resistance of pins #1 and pin #2 again.
   
   Your multimeter SHOULD NOT register continuity (it should register OL).

5. 5

   Repeat steps 3 through 4 several times just to make sure of your test results.

Let's find out what your specific multimeter test results mean:

CASE 1: Your multimeter registered the indicated continuity test results. This confirms that the 'idle' circuit of the throttle switch is OK.

Your next step is to check the 'Wide Open Throttle (WOT)' circuit of the throttle valve switch. Go to: TEST 3: Testing The Continuity Of The WOT Circuit.

CASE 2: Your multimeter DID NOT register the indicated continuity test results. This tells you that the 'idle' switch part of the throttle valve switch is defective. Replace the throttle valve switch

Before replacing the throttle valve switch, I suggest that you make sure that its not misadjusted. For this procedure, go to: Adjusting the Throttle Valve Switch.