GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value

Yes

No

1

  1. Disconnect the idle control switch connector.
  2. Measure the voltage at the power supply side terminal of the idle control switch.

Does the voltage measure more than the specified value?

8 V

Go to Step 2

Go to Step 3

2

Inspect the voltage between the idle control switch output terminal and the pin number 10, 29 of the ECM.

Does the voltage vary when the idle control switch turns the idle up and down, but stay above the specified value?

8 V

Go to Step 3

Go to Step 4

3

Repair the wiring harness to the power source.

Did you complete the repair?

--

Go to Step 7

--

4

Replace the idle control switch and/or repair the wiring harness between the idle control switch and the ECM.

Did you complete the action?

--

Go to Step 7

--

5

Inspect the voltage between the idle control switch output terminal and pin number 10, 29 of the ECM.

Does the voltage vary when the idle control switch turns idle up and idle down, but stay above the specified value?

8 V

System OK

Go to Step 6

6

Replace the ECM.

Did you complete the replacement?

--

Go to Step 7

--

7

Does the idle speed operate normally?

--

System OK

Go to Step 1