Electronic Throttle Body Tests (2005-2006 2.2L Chevrolet Cobalt)

TEST 4: TPS 2 Resistance Test (Part 2 Of 2)

The last test for TPS 2 is to make sure that the resistance value between terminal D and terminal H decreases as you open the throttle plate.

This resistance value should increase as you slowly close the throttle plate.

If TPS 2 is bad, then its resistance value will not decrease/increase as you open/close the throttle plate. Or its resistance reading will have gaps as you open and close the throttle plate.

These are the test steps:

1. 1

   Disconnect the throttle body from its electrical connector.

2. 2

   Place your multimeter in Ohms mode.

3. 3

   Connect one multimeter test lead to terminal D and the other to terminal H.
   
   NOTE: All connection are done on the male terminals of the connector of the throttle body itself.
   
   At this point I generally get a reading of about 2.4 K Ohms from a good TPS 2.

4. 4

   Slowly open the throttle plate by hand till it reaches its wide open throttle (WOT) position.
   
   The resistance value should decrease smoothly and without any gaps as you open the throttle plate. At this point I usually get a reading of about 1.1 K Ohms from a good TPS 2.
   
   If TPS 2 is defective, you'll see gaps in the resistance reading or the Ohms reading will stay stuck in one value.

5. 5

   Slowly close the throttle plate by hand and push the throttle plate so that it completely closes.
   
   The resistance value should increase smoothly and without any gaps as you close the throttle plate.
   
   At this point (the throttle plate pushed down and completely closed) I usually see a reading of about 3 K Ohms from a good TPS 2.

Let's examine your test results:

CASE 1: The resistance decreased/increased without any gaps. This is the correct test result.

If TPS 2 has passed TEST 2 and TEST 3, then you can conclude that it's not defective.

Your last test is to test the throttle actuator motor. Go to: TEST 5: Testing The TAC Motor.

CASE 2: The multimeter DID NOT register the indicated resistance values. This lets you know that TPS 2 is bad. You'll need to replace the throttle actuator assembly.

TEST 5: Testing The TAC Motor

For our last electronic throttle body test, we're gonna make sure that the throttle actuator motor is OK.

To be a bit more specific, we want to make sure that the motor has not suffered an internal short-circuit or open-circuit.

If the throttle actuator motor has an internal short-circuit problem, then you'll see a resistance reading below 1 Ohm.

If the throttle actuator motor has an internal open-circuit problem, you'll see a resistance reading in the thousands (K) of Ohms or the letters OL (if you're using a digital multimeter).

These are the test steps:

1. 1

   Disconnect the throttle body from its electrical connector.

2. 2

   Place your multimeter in Ohms mode.

3. 3

   Connect one multimeter test lead to terminal E and the other to terminal F.

4. 4

   Your multimeter should read continuity.
   
   If the resistance reading is below 1 Ohm, then the motor has an internal short-circuit problem.
   
   If the resistance reading is in the K Ohms range or your multimeter reads OL, then the motor has an internal open-circuit problem.
   
   The resistance reading I've gotten from good throttle actuator motors has been between 2 and 12 Ohms.

Let's examine your test results:

CASE 1: The multimeter registered continuity between terminal E and F. This is the correct test result.

If your 2005-2006 2.2L Chevy Cobalt's electronic throttle body passed TEST 1 and TEST 2, then you can conclude that the electronic throttle body is OK and not defective.

CASE 2: The multimeter DID NOT register continuity. This lets you know that the TAC motor is defective. You'll need to replace the throttle actuator assembly.