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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1996 🢒 Chevy G Van 🢒 Engine 🢒 Engine Controls - 6.5L 🢒 DTC P0231 Fuel Pump Feedback Circuit Low Voltage

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Fuel Pump Controls


Object Number: 50164 Size: FS
Engine Controls Components
Fuel Lift Pump Electrical Circuit
Fuel Controls
Glow Plug Controls
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The status of the lift pump is monitored by the PCM. This signal is also used in order to store a DTC if the fuel pump relay is defective or if the fuel pump voltage is lost while the engine is running. There should be about 12 volts on circuit 120 during the glow plug cycle. This is a type B DTC.

Conditions for Setting the DTC
    • The fuel lift pump is commanded ON.
    • The difference between the ignition voltage and the fuel pump voltage is greater than 4 volts.
    • The condition was met for 2 seconds.

Action Taken When the DTC Sets

No action taken.

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 after forty consecutive warm-up cycles during which the diagnostic does not fail (the coolant temperature has risen 5°C (40°F) from start up coolant temperature and the engine coolant temperature exceeds 71°C (160°F) of that same ignition cycle).
    • Use of a Scan Tool will clear the DTC codes.

Diagnostic Aids

This DTC will not check the fuel pump for operation.

Test Description

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

  1. This fuel pump can also be felt for a pulsing which will also determine if the fuel pump is working.

  1. This Step checks the fuel lift pump circuit.

  1. This Step checks if the PCM is sending a signal to turn the fuel pump ON. The scan tool display Lift Pump Voltage will indicate if the feed back voltage is being sent back to the PCM.

Step

Action

Value(s)

Yes

No

1

Important: Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and the failure Records for reference, as the data will be lost when the 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. Install the scan tool.
  2. Turn the ignition ON.
  3. Use the Scan Tool in order to command the fuel pump ON.

Does the Scan Tool indicate the fuel pump is operating?

--

Go to Diagnostic Aids

Go to Step 3

3
  1. Turn the ignition OFF.
  2. With a J 39200 connected to ground, backprobe the fuel lift pump signal circuit at the PCM.
  3. Probe the fuel pump test terminal with a fused jumper to B+.

Is the voltage at the specified value?

B+

Go to Step 8

Go to Step 4

4
  1. Remove the fuel pump relay.
  2. Verify the J 39200 is still connected.
  3. From underneath the U/H relay center, probe the A3 terminal with a fused jumper to B+.

Is the voltage at the specified value?

B+

Go to Step 5

Go to Step 6

5
  1. Check for a poor connection at the fuel pump relay center.
  2. If a problem is found, repair the problem as necessary.

Was a problem found?

--

Go to Step 17

--

6
  1. Check for an open or short to ground on the fuel pump signal circuit.
  2. If a problem is found, repair the problem as necessary.

Was a problem found?

--

Go to Step 18

Go to Step 7

7
  1. Check for poor connections at the PCM and at the relay center.
  2. If a problem is found, repair the problem as necessary.

Was a problem found?

--

Go to Step 18

Go to Step 15

8
  1. Remove the fuel pump relay.
  2. Turn the ignition ON.
  3. Connect a test light to ground.
  4. Probe the fuel pump relay harness connector terminal B1.

Is the test light ON?

--

Go to Step 10

Go to Step 9

9

Repair the open in the battery feed circuit to the fuel pump relay.

Is the action complete?

--

Go to Step 18

--

10

Connect a test light between terminal number B1 and terminal number A1 of the fuel pump relay harness connector.

Is the test light ON?

--

Go to Step 12

Go to Step 11

11

Repair the open fuel pump relay ground circuit.

Is the action complete?

--

Go to Step 18

--

12
  1. Turn the ignition OFF.
  2. Connect a test light between terminal number B3 of the fuel pump relay harness connector and ground.
  3. Monitor the test light.
  4. Turn the ignition ON.

Does the test light come ON during the glow plug cycle and then go OFF after the glow plug cycle is complete?

--

Go to Step 16

Go to Step 13

13

Check for an open in the circuit from the fuel pump relay harness connector terminal number B3 and the PCM.

Was a problem found?

--

Go to Step 14

Go to Step 15

14

Repair the open in the fuel pump relay control circuit.

Is the action complete?

--

Go to Step 18

--

15

Replace the PCM.

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

Is the action complete?

--

Go to Step 18

--

16

Check for a malfunctioning connection at the fuel pump relay connector terminal number B3.

Was a problem found?

--

Go to Step 18

Go to Step 17

17

Replace the fuel pump relay. Refer to Fuel Pump Relay Replacement .

Is the action complete?

--

Go to Step 18

--

18
  1. Use the Scan Tool Clear Info function in order to diagnosis the vehicle.
  2. Road test the vehicle.
  3. Check for DTCs, either Current or history.
  4. Review the test status information. If last test Failed or is not present and no DTCs are present, this will indicate that the repair is complete. If the status test(s) Failed or DTCs are present, begin the diagnosis on that DTC.

Are the repairs complete?

--

Go to Step 19

--

19

Use the Scan Tool in order to select Capture Info, Review Info.

Are there any DTCs displayed that have not been diagnosed?

--

Go to the Applicable DTC Table

System OK