GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2001 🢒 GMC C-Series Medium Duty Truck B7 🢒 Body and Accessories 🢒 Instrument Panel, Gauges, and Console 🢒 Engine Coolant Temperature Gage Inaccurate or Inoperative

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 ECT parameter in the PCM Engine Data 1 data list.

Does the ECT parameter match the engine coolant temperature gauge display?

--

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3
  1. Turn the ignition OFF.
  2. Disconnect the engine coolant temperature (ECT) gauge sensor.
  3. Turn the ignition ON, with the engine OFF.

Does the ECT gauge display at or below the specified value?

37°C (100°F)

Go to Step 4

Go to Step 6

4
  1. Turn the ignition OFF.
  2. Connect the J 33431-C Signal Generator and Instrument Panel Tester between the signal circuit of the engine coolant temperature gauge 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 ECT gauge display at or above the specified value?

138°C (280°F)

Go to Step 7

Go to Step 5

5

Test the ECT gauge sensor signal circuit 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 12

Go to Step 9

6

Test the ECT gauge sensor signal circuit 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 12

Go to Step 9

7

Test the ECT gauge ground circuit for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 8

8

Inspect for poor connections at the harness connector of the ECT gauge 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 12

Go to Step 10

9

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 12

Go to Step 11

10

Replace the ECT gauge sensor. Refer to Engine Coolant Temperature Sensor Replacement in Engine Controls - 8.1 L or to Cat® Medium Duty Diesel Engine Manual - LG5.

Did you complete the replacement?

--

Go to Step 12

--

11

Replace the IPC. Refer to Instrument Cluster Replacement .

Did you complete the replacement?

--

Go to Step 12

--

12
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2