GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

  1. Disconnect the engine coolant temperature switch.
  2. Observe the lamp.

Does the indicator lamp turn off?

--

Go to Step 2

Go to Step 3

2

Replace the engine coolant temperature switch.

Does the indicator lamp turn off?

--

System OK

--

3

  1. Disconnect the engine oil pressure indicator switch.
  2. Observe the lamp.

Does the indicator lamp turn off?

--

Go to Step 4

Go to Step 5

4

Replace the engine oil pressure indicator switch.

Does the indicator lamp turn off?

--

System OK

--

5

  1. Disconnect the multifunction alarm module.
  2. Observe the lamp.

Does the indicator lamp turn off?

--

Go to Step 6

Go to Step 7

6

Connect a test lamp from the engine oil pressure indicator switch harness connector to B+.

Did the test lamp light?

--

Go to Step 8

Go to Step 9

7

Repair the short to ground in CKT 1377 (LT BLU) between the instrument cluster and the multifunction alarm module.

Does the indicator lamp turn off?

--

System OK

--

8

Repair the short to ground in CKT 231 (TAN/BLK) between the engine coolant temperature switch and the multifunction alarm mode.

Does the indicator lamp turn off?

--

System OK

--

9

Connect a test lamp from the engine coolant temperature switch harness to B+.

Did the test lamp light?

--

Go to Step 10

Go to Step 11

10

Repair the short to ground in CKT 1675 (BRN) between the engine coolant temperature switch and the multifunction alarm module.

Does the indicator lamp turn off?

--

System OK

--

11

Replace the multifunction alarm module.

Does the indicator lamp turn off?

--

System OK

--