P1668

DTC P1668: Engine Coolant Temperature (ECT) Signal Output

Wiring Diagram:

Circuit Description
The engine coolant temperature gauge is directly controlled by the Engine Control Module (ECM) based on information received from the Engine Coolant Temperature (ECT) sensor. When the key is ON, the ECM receives battery voltage from the Instrument Panel Cluster (IPC) and senses if the circuit contains a fault by using a diagnostic feedback signal.

Conditions for Setting the DTC
- Ignition ON.
- An open, a short to ground, or a short to battery condition in the engine coolant temperature output circuit exists.

Action Taken When the DTCs Sets
- The Malfunction Indicator Lamp (MIL) will not illuminate.
- The ECM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers.
- A history DTC is stored.

Conditions for Clearing the MIL/DTC
- The MIL will turn OFF at the end of a consecutive validation cycle in which the diagnostic runs without a fault.
- A history DTC will clear after 40 consecutive warm up cycles without a fault.
- DTC(s) can be cleared by using the scan tool.

Diagnostic Aids
An Intermittent problem may be caused by a poor connection, rubbed through wire insulation, or wire that is broken inside the insulation. Any circuitry, that is suspected as causing the complaint, should be thoroughly checked for the following conditions.
- Backed-out terminals
- Improper mating
- Broken locks
- Improperly formed
- Damaged terminals
- Poor terminals to wire connection
- Physical damage to the wiring harness

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DTC Troubleshooting