GM Service Manual Online
For 1990-2009 cars only

Object Number: 29557  Size: LF
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice
Engine Controls Components
Crankshaft Position, Optical/Fuel Temperature Sensor, and Injection Timing Stepper Motor
OBD II Symbol Description Notice

Circuit Description

The fuel temperature sensor is a thermistor that controls signal voltage to the PCM. When the fuel is cold, the sensor resistance is high, therefore the PCM will see high signal voltage. As fuel warms, sensor resistance becomes less and voltage drops. The fuel temperature sensor is integrated with the optical sensor. This is a type B DTC.

Conditions for Setting the DTC

    • Engine operating for 8 minutes.
    • Fuel temperature less than or equal to 17°C (63°F).
    • Conditions met for 2 seconds.

Action Taken When the DTC Sets

Poor idle quality during hot conditions.

Conditions for Clearing the MIL/DTC

    • The PCM will turn the MIL off after three consecutive trips without a fault condition.
    • A History DTC will clear when forty consecutive warm-up cycles that the diagnostic does not fail (coolant temperature has risen 5°C (40°F) from start up coolant temperature and engine coolant temperature exceeds 71°C (160°F) that same ignition cycle.
    • Use of a Scan Tool

Diagnostic Aids

A scan tool reads fuel temperature in degrees centigrade. After engine is started, the temperature should rise steadily. A faulty connection, or an open in the signal circuit.

Test Description

Number(s) below refer to the Step number(s) on the Diagnostic Table.

  1. This Step determines if DTC P0183 is a hard failure or an intermittent condition.

  2. This test simulates a DTC P0182. If the PCM recognizes the low signal voltage (high temp) the PCM and wiring are OK.

  3. This test will determine if signal circuit is open. There should be 5 volts at sensor connector if measured with J 39200-DVM. This will determine if there is a wiring problem or a faulty PCM.

Step

Action

Value(s)

Yes

No

1

Important: Before clearing DTC(s) use the Scan Tool Capture Info to record freeze frame and failure records for reference, as data will be lost when Clear Info function is used.

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

  1. Scan Tool connected.
  2. Start and idle engine.
  3. Monitor the Fuel Temp display on Scan Tool.

Is Fuel Temp less than or equal to the specified value?

17°C (63°F)

Go to Step 3

Go to Step 5

3

  1. Engine OFF.
  2. Ignition ON.
  3. Disconnect the Optical/Fuel Temperature sensor connector.
  4. Jumper the Fuel Temperature harness terminals together.

Does the Scan Tool display fuel temperature greater than the specified value?

105°C (221°F)

Go to Step 6

Go to Step 4

4

Jumper the Fuel Temperature sensor signal circuit to a known good ground.

Does the Scan Tool display a Fuel Temp greater than the specified value?

105°C (221°F)

Go to Step 7

Go to Step 8

5

DTC is intermittent. If no other DTC(s) are stored, refer to Diagnostic Aids. If additional DTCs are stored, refer to those table(s) first.

Are any other DTCs stored?

--

Go to the Applicable DTC Table

Go to Diagnostic Aids

6

Inspect the sensor connector and PCM connector for proper connection.

Was a problem found?

--

Go to Step 9

Go to Step 10

7

Check the Fuel Temperature sensor ground circuit for an open between the Fuel Temp sensor and the PCM.

Was a problem found?

--

Go to Step 9

Go to Step 11

8

Check the Fuel Sensor signal circuit for an open between the Fuel Temp sensor and the PCM.

Was a problem found?

--

Go to Step 9

Go to Step 11

9

Repair the circuit as necessary.

Is the action complete?

--

Go to Step 12

--

10

Replace the injection pump. Refer to Fuel Injection Pump Replacement

Is the action complete?

--

Go to Step 12

--

11

Replace the faulty PCM.

Important: If the PCM is faulty, the new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming

Is the action complete?

--

Go to Step 12

--

12

  1. Using the Scan Tool select DTC, Clear Info.
  2. Start engine and idle at normal operating temperature.
  3. Select DTC, Specific then enter the DTC number which was set.
  4. Operate vehicle within the conditions for this DTC as specified in the supporting text.

Does the Scan Tool indicate that this diagnostic Ran and Passed?

__

Go to Step 13

Go to Step 2

13

Using the Scan Tool, select Capture Info, Review Info.

Are there any DTCs displayed that have not been diagnosed?

__

Go to the Applicable DTC Table

System OK