For 1990-2009 cars

## Engine Coolant Temperature Gage Inaccurate or Inoperative Pontiac

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Instrument Cluster System Check? | -- | Go to Step 2 | Go to Instrument Cluster System Check
2 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the engine coolant temperature (ECT) sensor connector.
3. Connect 1 red clip lead of the J 33431-C tester to the ECT sensor connector terminal C.
4. Connect 1 red clip lead of the J 33431-C tester to ground.
5. Turn the ignition switch to the RUN position.
6. Adjust the J 33431-C resistance dials to 40 ohms.
7. Adjust the J 33431-C resistance dials to 85 ohms.
8. Adjust the J 33431-C resistance dials to 1300 ohms.

Does the coolant temperature gauge indicate maximum, midscale, and minimum temperature?

--

Go to Step 6

Go to Step 3

3 | Inspect 1 of the following circuits for an open or a short to ground:

1. For U5O and U2F, inspect CKT 135 (DK GRN) and CKT 36 (LT GRN).
2. For UB3, inspect CKT 36 (LT GRN).

Was a poor connection found?

--

Go to Step 12

Go to Step 7

4 | Inspect the ECT sensor ground for an open. Repair as necessary. Is the ground OK? | -- | Go to Step 6 | --
5 | Inspect the following terminals for proper terminal contact:

1. Connector C101 terminal B3
2. Connector C200 terminal A8
3. The instrument cluster connector terminal A9 (UB3 only)
4. The instrument cluster connector terminal A11 (U5O/U2F only)

Was a poor connection found?

--

Go to Step 7

--

6 | Inspect the ECT sensor connector for proper terminal contact. Is the contact OK? | -- | Go to Step 10 | Go to Step 13
7 | Inspect connector C101 cavity B3 for proper terminal contact. Was a poor connection found? | -- | Go to Step 14 | Go to Step 8
8 | Inspect connector C200 cavity A8 for proper terminal contact. Was a poor connection found? | -- | Go to Step 15 | Go to Step 9
9 | Inspect 1 of the following terminals for proper terminal contact:

• | The instrument cluster connector terminal cavity A9 (UB3 only)

• | The instrument cluster connector terminal cavity A11 (U50/U2F only)

Was a poor connection found?

--

Go to Step 16

Go to Step 11

10 | Inspect the ECT sensor connector for proper terminal contact. Was a poor connection found? | -- | Go to Step 13 | --
11 | Replace the instrument cluster. Refer to IP Cluster Replacement in Instrument Panel, Gauges, and Console. Did you complete the repair? | -- | Go to Instrument Cluster System Check | --
12 | Repair the open or the short to ground in 1 of the following circuits:

1. For U5O and U2F, repair CKT 135 (DK GRN) and CKT 36 (LT GRN).
2. For UB3, repair CKT 36 (LT GRN).

Did you complete the repair?

--

Go to Instrument Cluster System Check

--

13 | Replace the engine coolant temperature sensor. Refer to Engine Coolant Temperature Sensor Replacement in Engine Controls. Did you complete the repair? | -- | Go to Instrument Cluster System Check | --
14 | Repair connector C101 cavity B3. Refer to Terminal Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Instrument Cluster System Check | --
15 | Repair connector C200 cavity A8. Refer to Terminal Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Instrument Cluster System Check | --
16 | Repair the instrument cluster connector terminal cavity A9 (UB3 only) or cavity A11 (U50/U2F only). Refer to Terminal Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Instrument Cluster System Check | --

## Engine Coolant Temperature Gage Inaccurate or Inoperative Buick

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Instrument Cluster System Check? | -- | Go to Step 2 | Go to Instrument Cluster System Check
2 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the engine coolant temperature (ECT) sensor connector.
3. Connect 1 red clip lead of the J 33431-C tester to the ECT sensor connector terminal C.
4. Connect 1 red clip lead of the J 33431-C tester to ground.
5. Turn the ignition switch to the RUN position.
6. Adjust the J 33431-C resistance dials to 40 ohms.
7. Adjust the J 33431-C resistance dials to 85 ohms.
8. Adjust the J 33431-C resistance dials to 1300 ohms.

Does the coolant temperature gauge indicate maximum, midscale, and minimum temperature?

--

Go to Step 4

Go to Step 3

3 | Inspect CKT 36 (LT GRN) for an open or short to ground. Was there a problem with CKT 36? | -- | Go to Step 10 | Go to Step 5
4 | Inspect the ECT sensor connector for proper terminal contact. Was a poor connection found? | -- | Go to Step 12 | Go to Step 8
5 | Inspect connector C101 cavity B3 for proper terminal contact. Was a poor connection found? | -- | Go to Step 11 | Go to Step 6
6 | Inspect connector C200 cavity A8 for proper terminal contact. Was a poor connection found? | -- | Go to Step 11 | Go to Step 7
7 | Inspect the instrument cluster connector terminal cavity B11 for proper terminal contact. Was a poor connection found? | -- | Go to Step 11 | Go to Step 9
8 | Replace the engine coolant temperature sensor. Refer to Engine Coolant Temperature Sensor Replacement in Engine Cooling. Is the replacement complete? | -- | Go to Instrument Cluster System Check | --
9 | Replace the instrument cluster. Refer to IP Cluster Replacement in Instrument Panel, Gauges, and Console. Is the replacement complete? | -- | Go to Instrument Cluster System Check | --
10 | Repair the open or short to ground in CKT 36 (LT GRN). Refer to Repairing Damaged Wire Insulation in Wiring Systems. Is the repair complete? | -- | Go to Instrument Cluster System Check | --
11 | Replace the instrument cluster connector terminal cavity B11. Refer to Terminal Repairs in Wiring Systems. Is the repair complete? | -- | Go to Instrument Cluster System Check | --
12 | Repair poor connection. Is the repair complete? | -- | Go to Instrument Cluster System Check | --