GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2001 🢒 Catera 🢒 Body and Accessories 🢒 Instrument Panel, Gauges, and Console 🢒 Engine Coolant Temperature Gage Inaccurate or Inoperative

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step tests for a short to ground in the signal circuit.

    2.

  2. This step tests for an open, for a high resistance, or for a short to voltage in the signal circuit.

    3.

  3. DTCs will set in the IPC when you perform this diagnostic table.

Step

Action

Value(s)

Yes

No

Schematic Reference: Instrument Cluster Schematics

1

Did you perform the Instrument Cluster Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - Instrument Cluster

2
  1. Install a scan tool.
  2. Turn the ignition ON, with the engine OFF.
  3. With the scan tool, observe the Coolant Temp parameter in the IPC data list.

Does the Coolant Temp parameter match the gage display?

--

Go to Step 3

Go to Step 4

3

With a scan tool, observe the ECT Sensor parameter in the PCM data list.

Does the Coolant Temp parameter match the ECT Sensor parameter?

--

Go to Engine Overheating in Engine Cooling

Go to Step 4

4

  1. Turn the ignition OFF.
  2. Disconnect C105.
  3. Turn the ignition ON, with the engine OFF.

Does the engine coolant temperature gage display at the specified value or below the specified value?

37°C (100°F)

Go to Step 5

Go to Step 7

5

  1. Turn the ignition OFF.
  2. Connect the J 33431-C Signal Generator and Instrument Panel Tester between the signal circuit of the coolant temperature sensor and a good ground.

    3. Important: Verify the J 33431-C resistance setting with a DMM.

  3. Set the resistance on the J 33431-C to 44 ohms.
  4. Turn the ignition ON, with the engine OFF.

Does the engine coolant temperature gage display at or above the specified value?

138°C (280°F)

Go to Step 8

Go to Step 6

6

Test the signal circuit of the coolant temperature sensor for an open, for a high resistance, or for a short to voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 11

7

Test the signal circuit of the coolant temperature sensor for a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 11

8

Test the signal circuit of the coolant temperature sensor for an open, for a high resistance, for a short to ground, or for a short to battery voltage between C105 and the ECT sensor. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 9

9

Inspect for a high resistance or for a poor connection at the case ground of the ECT sensor.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 10

10

Inspect for poor connections at the harness connector of the ECT sensor. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 12

11

Inspect for poor connections at the harness connector of the IPC. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 13

12

Replace the ECT sensor. Refer to Engine Coolant Gauge Sensor Replacement in Engine Cooling.

Did you complete the replacement?

--

Go to Step 14

--

13

Replace the IPC. Refer to Instrument Cluster Replacement .

Did you complete the replacement?

--

Go to Step 14

--

14

  1. Use the scan tool in order to clear the IPC DTCs.
  2. Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2