DTC P1673 Engine Coolant Temperature Lamp Control Circuit. Pontiac Grand Prix 1999

For 1990-2009 cars only

Makes 🢒 Pontiac 🢒 1999 🢒 Grand Prix 🢒 Engine 🢒 Engine Controls - 3.1L 🢒 DTC P1673 Engine Coolant Temperature Lamp Control Circuit

Cell 20: Power, Ground, MIL, and DLC
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

Output Driver Modules (ODMs) are used by the PCM to turn on many of the current-driven devices that are needed to control various engine and Transaxle functions. Each ODM is capable of controlling up to 7 separate outputs by applying ground to the device which the PCM is commanding ON. DTC P1673 set indicates an improper voltage level on the output circuit that controls the engine hot lamp.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

•	An improper voltage level has been detected on the engine hot lamp control circuit.

•	The above conditions are present for at least 30 seconds.

Action Taken When the DTC Sets

The PCM stores conditions which were present when the DTC set as Failure Records only. This information will not be stored as Freeze Frame Records.

Conditions for Clearing the MIL/DTC

•	The DTC becomes history when the conditions for setting the DTC are no longer present.

•	The history DTC clears after 40 malfunction free warm-up cycles.

•	The PCM receives a clear code command from the scan tool.

Diagnostic Aids

Check for the following conditions:

Important: : Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.

•	Poor terminal connection.

Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Use a corresponding mating terminal to test for proper tension. Refer to Intermittents and Poor Connections Diagnosis , and Connector Repairs Wiring Systems.

•	Damaged harness.

Inspect the wiring harness for damage. If the harness appears to be OK, observe the sensor display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the sensor display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems.

•	Inspect the PCM and the engine grounds for clean and secure connections.

If the DTC is determined to be intermittent, reviewing the Fail Records can be useful in determining when the DTC was last set.

Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table:

Normally, ignition feed voltage should be present on the control circuit with the PCM disconnected and the ignition turned on.

Checks for a shorted component or a short to battery positive voltage on the control circuit. Either condition would result in a measured current of over 500 milliamps. Also checks for a component that is causing an open circuit while being operated, resulting in a measured current of 0 milliamps.

Checks for a short to voltage on the control circuit.

This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming .

DTC P1673 - Engine Hot Lamp Control Circuit

Step	Action	Value(s)	Yes	No
1	Was the Powertrain OBD System Check performed?	--	Go to Step 2	Go to the Powertrain On Board Diagnostic (OBD) System Check
2	Turn off the ignition switch. Disconnect the PCM. Turn on the ignition switch. Using a J 39200 DMM, measure voltage between the engine hot lamp control circuit at the PCM harness connector and ground. Is the voltage near the specified value?	B+	Go to Step 3	Go to Step 6
3	Connect the J 39200 DMM to measure current between the engine hot lamp control circuit at the PCM harness connector and ground. Monitor the current reading on the J 39200 DMM for at least 2 minutes. Does the current reading remain between the specified values?	0.05-0.5 Amps (50-500 mA)	Go to Step 11	Go to Step 4
4	Turn off the ignition switch. Disconnect the instrument panel (leave the PCM disconnected). Turn on the ignition switch. Using a J 39200 DMM, measure voltage between the engine hot lamp control circuit and ground. Is the voltage at the specified value?	0.0V	Go to Step 10	Go to Step 5
5	Locate and repair short to voltage in the engine hot lamp control circuit. Refer to Wiring Repairs . Is the action complete?	--	Go to Step 15	--
6	Check the ignition feed fuse for the instrument panel indicators. Is the fuse blown?	--	Go to Step 7	Go to Step 8
7	Locate and repair short to ground in ignition feed circuit for the instrument panel indicators. Refer to Wiring Repairs . Replace the fuse. Is the action complete?	--	Go to Step 15	--
8	Disconnect the instrument cluster. Turn on the ignition switch. Measure voltage between the ignition feed circuit for the instrument cluster indicators and ground. Is voltage near the specified value?	B+	Go to Step 9	Go to Step 13
9	Check the engine hot lamp control circuit for an open or a short to ground. If a problem is found, repair the engine hot lamp control circuit. Refer to Wiring Repairs . Was a problem found?	--	Go to Step 15	Go to Step 10
10	Check the engine hot lamp control circuit and the instrument panel indicators ignition feed circuit for a poor connection at the instrument panel and at the PCM. If a problem is found, replace faulty terminal(s). Refer to Testing for Continuity Intermittents and Poor Connections Diagnosis Repairing Connector Terminals and Connector Repairs . Was a problem found?	--	Go to Step 15	Go to Instrument Cluster System Check
11	Turn off the ignition switch. Reconnect the PCM. Disconnect the instrument cluster. Turn on the ignition switch. Connect a J 35616-200 test lamp between the engine hot lamp control circuit and the ignition feed circuit at the instrument panel harness connector. Using the scan tool outputs test function, cycle the engine hot lamp on and off. Does the J 35616-200 test lamp flash on and off?	--	Go to Diagnostic Aids	Go to Step 12
12	Check the engine hot lamp control circuit for a poor connection at the PCM. If a problem is found, replace faulty terminal. Refer to Testing for Continuity , Intermittents and Poor Connections Diagnosis , Repairing Connector Terminals and Connector Repairs . Was a problem found?	--	Go to Step 15	Go to Step 14
13	Locate and repair open in the ignition feed circuit to the I/P indicators. Refer to Wiring Repairs . Is the action complete?	--	Go to Step 15	--
14	Important: : The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Is the action complete?	--	Go to Step 15	--
15	Review and record scan tool Fail Records data. Clear DTCs. Operate the vehicle within Fail Records conditions. Using a scan tool, monitor Specific DTC info for DTC P1673 until the DTC P1673 test runs. Does the scan tool indicate DTC P1673 failed this ignition?	--	Go to Step 2	System OK