GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The fuel temperature sensor is a thermistor. The engine control module (ECM) supplies the fuel temperature sensor a reference voltage of 5 volts on the signal circuit and also provides a ground circuit to the sensor. When the fuel temperature sensor is cold, the resistance is high. The fuel temperature sensor signal voltage remains near the supplied voltage cold and decreases the signal voltage as the sensor warms. The control module monitors the fuel temperature sensor signal circuit in order to calculate the temperature of the fuel entering the engine. If the ECM detects an excessively high fuel temperature sensor voltage, a low temperature indication, this DTC will set.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0183 Fuel Temperature Sensor High Voltage

Conditions for Running the DTC

The vehicle has been driven for more than 8 minutes.

Conditions for Setting the DTC

The fuel temperature sensor is less than -30°C (-22°F) for 2 seconds.

Action Taken When the DTC Sets

    • The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
    • The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

Conditions for Clearing the MIL/DTC

    • The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
    • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
    • Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

    • If a short to a separate 5-volt source occurs, this DTC may set. If this is the condition, a continuity test to all other ECM circuits will be necessary in order to diagnose the specific circuit.
    • After starting a cold engine, the fuel temperature sensor should be within a few degrees of the intake air temperature (IAT) reading.
    • Use the Temperature vs. Resistance table to test the fuel temperature sensor at various temperature levels and to evaluate the possibility of a skewed sensor.
    • If the condition is suspected of being intermittent, refer to Intermittent Conditions .

Test Description

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

  1. If DTC P0183 can only be repeated by duplicating the Failure Records, refer to the Temperature vs Resistance table. The table may be used to test the fuel temperature sensor at various temperatures to evaluate the possibility of a shifted sensor that may be shorted above or below a certain temperature. If this is the case, replace the fuel temperature sensor. If the fuel temperature sensor appears to be OK, the malfunction is intermittent. Refer to Diagnostic Aids.

  2. 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

Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check - Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

  1. Turn ON the ignition, with the engine OFF.
  2. Observe the Fuel Temperature Sensor parameter with a scan tool.

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

-30°C (-22°F)

Go to Step 4

Go to Step 3

3

  1. Observe the Freeze Frame/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 or as closely as possible to the Freeze Frame/Failure Records conditions.

Does the DTC reset?

--

Go to Step 4

Go to Diagnostic Aids

4

  1. Turn OFF the ignition.
  2. Disconnect the fuel temperature sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the signal circuit of the fuel temperature sensor to a good ground with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Is the voltage more than the specified value?

5.2 V

Go to Step 5

Go to Step 6

5

Important: If a short to battery voltage occurs, the fuel temperature sensor may be damaged.

Test the fuel temperature sensor signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 12

6

  1. Connect a 3-amp fused jumper between the signal circuit of the fuel temperature sensor and the low reference circuit. Refer to Using Fused Jumper Wires in Wiring Systems.
  2. Observe the Fuel Temperature Sensor parameter with the scan tool.

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

138°C (280°F)

Go to Step 10

Go to Step 7

7

  1. Turn OFF the ignition.
  2. Connect a 3-amp fused jumper between the signal circuit of the fuel temperature sensor and a 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?

138°C (280°F)

Go to Step 9

Go to Step 8

8

Test the fuel temperature sensor signal circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 12

9

Test the low reference circuit of the fuel temperature sensor for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 12

10

Test the signal circuit of the fuel temperature sensor for a short to any other 5-volt reference circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 11

11

Test for an intermittent and for a poor connection at the fuel temperature sensor. 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 15

Go to Step 13

12

Test for an intermittent and for a poor connection at the engine control module (ECM). 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 15

Go to Step 14

13

Replace the fuel temperature sensor. Refer to Fuel Temperature Sensor Replacement .

Did you complete the replacement?

--

Go to Step 15

--

14

Replace the ECM. Refer to Engine Control Module Replacement .

Did you complete the replacement?

--

Go to Step 15

--

15

  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 16

16

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK