GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The primary fuel level sender and the secondary fuel level sender changes resistance based on fuel level. The powertrain control module (PCM) 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 resistance of both fuel level senders are low and the PCM senses a low 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 resistance of the fuel level senders are high and the PCM senses a high signal voltage. The PCM 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 PCM sends the fuel level percentage via the class 2 serial data circuit to the instrument cluster in order to control the fuel gage. The fuel level information is also used for misfire and evaporative emission (EVAP) diagnostics.

This diagnostic tests for a lower than normal secondary fuel level sender signal.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P2067 Fuel Level Sensor 2 Circuit Low Voltage

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

    • The secondary sender output is less than 0.39 volts.
    • The above condition is present for greater than 30 seconds.

Action Taken When the DTC Sets

    • The fuel gage defaults to empty.
    • The low fuel indicator illuminates.
    • The PCM records the operating conditions at the time the diagnostic fails. The PCM 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.
    • The PCM receives the clear code command from the scan tool.

Diagnostic Aids

Use the Freeze Frame and/or Failure Records data in order to locate an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data may aid in determining the number of miles since the DTC set. The Fail Counter and Pass Counter can also aid in determining the number of ignition cycles that the diagnostic reported a pass and/or fail. Operate the vehicle within the same freeze frame conditions (RPM, engine load, vehicle speed, temperature, etc.). This will isolate when the DTC failed.

Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

The number below refers to the step number on the diagnostic table.

  1. Tests for the proper operation of the circuit in the high voltage range.

Step

Action

Values

Yes

No

Schematic Reference: Instrument Cluster Schematics

Connector End View Reference: Master Electrical Component List in Wiring Systems

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Install the scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With the scan tool, observe the Fuel Tank Level Remaining % parameter in the powertrain control module (PCM) Enhanced evaporative emission (EVAP) Data list.

Does the scan tool indicate that the Fuel Tank Level Remaining % parameter is greater than the specified value?

98%

Go to Step 3

Go to Diagnostic Aids

3

  1. Turn OFF the ignition.
  2. Disconnect C152.
  3. Turn ON the ignition, with the engine OFF.
  4. With the scan tool, observe the Fuel Tank Level Remaining % parameter.

Does the scan tool indicate that the Fuel Tank Level Remaining % parameter is less than the specified value?

4%

Go to Step 5

Go to Step 4

4

Test the signal circuit of the fuel level sender for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 7

5

Test the signal circuit of the fuel level sender for a short to ground between C152 and the fuel level sender. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 6

6

Inspect for poor connections at the harness connector of the fuel level sender. 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 10

Go to Step 8

7

Inspect for poor connections at the harness connector of the PCM. 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 10

Go to Step 9

8

Replace the fuel level sender. Refer to the following procedures:

    •  Fuel Level Sensor Replacement in Engine Controls - 4.8L, 5.3L and 6.0L
    •  Fuel Level Sensor Replacement in Engine Controls - 8.1L

Did you complete the replacement?

--

Go to Step 10

--

9

Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 10

--

10

  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK