GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2002 🢒 Grand Prix 🢒 Body and Accessories 🢒 Body Control System 🢒 DTC P1673

Circuit Description

Ignition 1 voltage is supplied from the fuse block to the instrument cluster (IPC) by the ignition 1 voltage circuit. The powertrain control module (PCM) controls the hot coolant indicator by grounding the hot coolant indicator control circuit through the underhood accessory wiring junction block. The PCM has an internal solid state device called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line which is monitored by the PCM. When the PCM is commanding a component ON, the voltage potential of the control circuit should be low, near 0 volts. When the PCM is commanding the control circuit to a component OFF, the voltage potential of the circuit should be high, near battery voltage. If the fault detection circuit senses a voltage other than what is expected, the DTC will set. The PCM will monitor the control circuit for the following:

    • A short to ground
    • A short to voltage
    • An open circuit

Conditions for Running the DTC
    • The ignition is ON.
    • The system voltage is between 9 and 18 volts.

Conditions for Setting the DTC
    • An improper voltage level has been detected on the hot coolant indicator control circuit.
    • The condition is present for at least 30 seconds.

Action Taken When the DTC Sets
    • The PCM will not illuminate the malfunction indicator lamp (MIL).
    • The PCM will store conditions which were present when the DTC set as Failure Records data only. This information will not be stored as Freeze Frame data.

Conditions for Clearing the MIL/DTC
    • A History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
    • The DTC can be cleared by using a scan tool.

Diagnostic Aids

If the condition is not present, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

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

  1. Tests for voltage at the ignition 1 voltage circuit of the hot coolant indicator. The Instrument Cluster fuse supplies ignition 1 voltage to the hot coolant indicator.

    2.

  2. Verifies that the PCM is providing ground to the hot coolant indicator.

    3.

  3. Tests if ground is constantly being applied to the hot coolant indicator.

    4.

  4. The replacement PCM must be programmed.

Step

Action

Yes

No

Schematic Reference: Engine Cooling Schematics

Connector End View Reference: Cooling System Connector End Views

1

Did you perform the Engine Cooling Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Engine Cooling

2
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, command the Engine Hot Lamp ON and OFF.

Does the hot coolant indicator turn ON and OFF with each command?

Go to Diagnostic Aids

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the IPC.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the ignition 1 voltage circuit of the hot coolant indicator with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 4

Go to Step 10

4

  1. Connect a test lamp between the control circuit of the hot coolant indicator and the ignition 1 voltage circuit of the hot coolant indicator.
  2. With a scan tool, command the Engine Hot Lamp ON and OFF .

Does the test lamp turn ON and OFF with each command?

Go to Step 8

Go to Step 5

5

Does the test lamp remain illuminated with each command?

Go to Step 7

Go to Step 6

6

Test the control circuit of the hot coolant indicator for a short to voltage or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 9

7

Test the control circuit of the hot coolant indicator for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 9

8

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

Did you find and correct the condition?

Go to Step 13

Go to Step 11

9

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

Did you find and correct the condition?

Go to Step 13

Go to Step 12

10

Repair the ignition 1 voltage circuit of the hot coolant indicator. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 13

--

11

Replace the hot coolant indicator lamp. Refer to Instrument Cluster Indicator Lamp Replacement in Instrument Panel, Gages, and Console.

Did you complete the replacement?

Go to Step 13

--

12

Important: Perform the programming procedure for the PCM.

Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 3.1L (LG8) or Powertrain Control Module Replacement in Engine Controls - 3.8L.

Did you complete the replacement?

Go to Step 13

--

13
  1. Use the scan tool in order to clear the DTCs .
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK