GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The fuel temperature sensor is a variable resistor. The fuel temperature sensor has a signal circuit and a low reference circuit. The fuel temperature sensor measures the fuel temperature of the fuel. The engine control module (ECM) supplies 5 volts to the fuel temperature signal circuit and a ground for the fuel temperature low reference circuit. When the fuel temperature sensor is cold, the sensor resistance is high. When the fuel temperature increases, the sensor resistance decreases. With high sensor resistance, the ECM detects a high voltage on the fuel temperature signal circuit. With lower sensor resistance, the ECM detects a lower voltage on the fuel temperature signal circuit. If the ECM detects an excessively high fuel temperature signal voltage indicating a low temperature, this DTC will set.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0183 Fuel Temperature Sensor Circuit High Voltage

Conditions for Running the DTC

    • The ignition switch is ON.
    • The battery voltage is between 10-16 volts.

Conditions for Setting the DTC

The ECM detects that the fuel temperature signal voltage is more than 4.8 volts.

Action Taken When the DTC Sets

    • The ECM illuminates the malfunction indicator lamp (MIL) and Reduced Engine Power indicator lamp, if fitted, when the diagnostic runs and fails.
    • The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Failure Records.
    • The ECM uses fuel temperature -29°C (-20.2°F) condition for starting the engine.
    • The ECM uses fuel temperature 90°C (194°F) condition for the engine running.
    • The ECM limits the fuel injection quantity for fail-safe operation.
    • The ECM closes the exhaust gas recirculation (EGR) valve and holds the EGR valve to a closed position.
    • The ECM inhibits cruise control.

Condition for Clearing the DTC

    • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
    • Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

    • Before starting a cold engine, the fuel temperature sensor and the intake air temperature (IAT) sensor temperature should be relatively close to each other.
    • Use the Temperature vs. Resistance table to test the fuel temperature sensor at various temperature levels to evaluate the possibility of a skewed sensor. A skewed sensor could result in poor driveability concerns. Refer to Temperature Versus Resistance .
    • If an intermittent condition is suspected, the following may cause an intermittent:
       - Poor connections
       - A misrouted harness
       - Rubbed through wire insulation
       - Broken wire inside the insulation
    • Inspect for the following conditions:
       - Poor connection at ECM--Inspect the harness connectors for the following conditions:
   • Backed-out terminals
   • Improper mating
   • Broken locks
   • Improperly formed or damaged terminals
   • Poor terminal to wire connection
       - Damaged harness--Inspect the wiring harness for damage. If the harness appears to be OK, observe the Engine Coolant Temperature display on the scan tool while moving the connectors and the wiring harness related to the sensor. A change in the display will indicate the location of the fault.

Test Description

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

  1. This step tests for the proper operation of the circuit in the low voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to voltage.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Observe the Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 3

Go to Diagnostic Aids

3

  1. Turn OFF the ignition.
  2. Disconnect the fuel temperature sensor connector.
  3. Connect a DMM between the signal circuit and the low reference circuit of the fuel temperature sensor harness.
  4. Turn ON the ignition, with the engine OFF.

Is the DMM voltage more than the specified range?

4.5-5.5 V

Go to Step 4

Go to Step 5

4

Important: The fuel temperature sensor may be damaged if the circuit is shorted to a voltage source.

  1. Test the signal circuit for a short to voltage circuit.
  2. Repair the circuits, as necessary.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 12

5

  1. Turn OFF the ignition.
  2. Disconnect the fuel temperature sensor.
  3. Connect a 3-amp fused jumper wire between the signal circuit of the fuel temperature sensor and the low reference circuit at the fuel temperatures sensor.
  4. Turn ON the ignition, with the engine OFF.
  5. Observe the Fuel Temperature Sensor parameter with a scan tool.

Is the Fuel Temperature Sensor parameter more than the specified value?

135°C (275°F)

Go to Step 9

Go to Step 6

6

  1. Turn OFF the ignition.
  2. Connect a 3-amp fused jumper wire between the signal circuit of the fuel temperature sensor and a known good ground.
  3. Turn ON the ignition, with the engine OFF.
  4. Observe the Fuel Temperature Sensor parameter with a scan tool.

Is the Fuel Temperature Sensor parameter more than the specified value?

-44.7°C (-48.4°F)

Go to Step 8

Go to Step 7

7

  1. Test the signal circuit between the engine control module (ECM) and the fuel temperature sensor for the following conditions:
  2. • An open circuit
    • High resistance
  3. Repair the circuits, as necessary.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 10

8

  1. Test the low reference circuit between the ECM and the fuel temperature sensor for the following conditions:
  2. • An open circuit
    • High resistance
  3. Repair the circuits, as necessary.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 11

9

  1. Turn OFF the ignition.
  2. Disconnect the fuel temperature sensor.
  3. Inspect for connections at the harness connector of the fuel temperature sensor.
  4. Repair the connections, as necessary.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 10

10

Important: The fuel temperature sensor may be damaged if the circuit is shorted to a voltage source.

  1. Test the signal circuit for a short to voltage circuit.
  2. Repair the circuit, as necessary.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 12

11

  1. Turn OFF the ignition.
  2. Disconnect the fuel ECM.
  3. Inspect for poor connections at the harness connector of the ECM.
  4. Repair the connections, as necessary.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 13

12

Replace the fuel temperature sensor. Refer to Fuel Injection Pump Replacement .

Did you complete the replacement?

--

Go to Step 14

--

13

Important: The new ECM must be programmed.

Replace the ECM. Refer to Engine Control Module Programming and Setup , Engine Control Module Replacement/Restore Fuel Rate Data , and Fuel Injector Flow Rate Programming .

Did you complete the replacement?

--

Go to Step 14

--

14

  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 2

Go to Step 15

15

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

 

Go to Diagnostic Trouble Code (DTC) List - Vehicle

System OK