DTC P2066. Cadillac STS 2005

For 1990-2009 cars only

Makes 🢒 Cadillac 🢒 2005 🢒 STS 🢒 Accessories 🢒 Navigation Systems 🢒 DTC P2066

DTC P2066 4.6L LH2

DTC Descriptor

DTC P2066: Fuel Level Sensor 2 Performance

Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Fuel Level Sensor Reference Voltage Circuit	P2067	--	--	P2066
Fuel Level Sensor Signal Secondary Circuit	P2067	P2068	P2068	P2066
Fuel Level Sensor Low Reference Circuit	--	P2068	P2068	P2066

The primary fuel level sender and the secondary fuel level sender changes resistance based on fuel level. The engine control module (ECM) monitors the signal circuits of the primary fuel level sender and the secondary fuel level sender in order to determine the fuel level. When the fuel tank is full, the resistances of both fuel level senders are high and the ECM senses a high signal voltage on both the signal circuits of the primary fuel level sender and the secondary fuel level sender. When the fuel tanks are empty, the resistances of the fuel level senders are low and the ECM senses a low signal voltage. The ECM uses the signal circuits of the primary fuel level sender and the secondary fuel level sender in order to calculate the percentage of remaining fuel in the tank. The ECM sends the fuel level percentage via serial data circuit to the instrument cluster in order to control the fuel gage.

Conditions for Running the DTC

The ignition is ON, with the engine running.

Conditions for Setting the DTC

The ECM does not detect a change in the secondary tank fuel level of at least 3 L (0.79 gal) over a distance of 320 km (200 miles)

Action Taken When the DTC Sets

•	The fuel gage defaults to empty.

•	The driver information center (DIC) displays the FUEL LEVEL LOW message.

•	The ECM records the operating conditions at the time that the diagnostic test fails. The ECM displays the failure information in the Failure Records on the scan tool.

Conditions for Clearing the 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.

Diagnostic Aids

A partially filled fuel tank and filling the fuel tank with the ignition ON or engine RUNNING may cause an inaccurate or erratic fuel gage. This condition may cause a fuel system DTC to set and the fuel gage to default to empty. Refer to Fuel Gage Description and Operation

Reference Information

Schematic Reference

•	Instrument Cluster Schematics

•	Engine Controls Schematics for the 4.6L engine

Connector End View Reference

•	Instrument Panel, Gages, and Console Connector End Views

•	Engine Control Module Connector End Views for the 4.6L engine

Description and Operation

Fuel Gage Description and Operation

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

Scan Tool Reference

Scan Tool Data List

Circuit/System Testing

Ignition OFF, remove the secondary fuel level sender and verify that there are no obstructions interfering with the fuel level sender.

⇒	If any interference is present, remove the obstruction.

If no interference is present, perform the fuel level sensor component test before replacing the secondary fuel level sensor.

Component Testing

Ignition OFF, disconnect the harness connector at the secondary fuel level sensor.
While sweeping the secondary fuel level sensor through its full range of motion, test for a minimum value less than 41 ohms and a maximum value greater than 119 ohms of resistance between signal terminal A and the low reference terminal D.

⇒	If not within the specified range, replace the secondary fuel level sensor.

Repair Instructions

•	Secondary Fuel Tank Module Replacement for the 4.6L engine

•	Control Module References for the ECM replacement, setup, and programming

DTC P2066 3.6L LY7