GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Saturn 🢒 2006 🢒 VUE - FWD 🢒 Vehicle Control Systems 🢒 Vehicle DTC Information 🢒 DTC P0629
Table 1: Relay Cavity Identification

Circuit Description

The DTC P0629 Fuel Pump Relay Control Circuit High Voltage diagnostic detects an incorrect voltage on the coil control circuit. The fuel pump relay, is controlled by the powertrain control module (PCM). The PCM energizes the relay coil for 2 seconds when the ignition switch is first turned ON and when ignition system reference pulses are detected. The fuel pump relay supplies ignition positive voltage to the fuel pump.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0629 Fuel Pump Relay Control Circuit High Voltage

Conditions for Running the DTC
    • Battery voltage is 10.5 volts or more.
    • DTC P0629 runs continuously with the above condition met.

Conditions for Setting the DTC
    • The PCM detects a higher than expected voltage on the coil control circuit .
    • The above condition is present for at least 1 second.

Action Taken When the DTC Sets
    • The control module stores the DTC information into memory when the diagnostic runs and fails.
    • The MIL will not illuminate.

Conditions for Clearing the MIL/DTC
    • A last test failed, or current DTC, clears when the diagnostic runs and passes.
    • Perform the scan tool Clear DTC Information function.

Diagnostic Aids

Check for any of the following conditions:

    • Check the resistance of the relay. The resistance across the coil terminals is 70-95 ohms at 20°C (68°F). The resistance across the switched terminals is infinite.
    • The relay electrical contacts may be pitted or sticking. Replace the relay if tapping gently on the relay or wiggling the relay causes a change in the relays operation.
    • The performance of the relay may be affected by temperature. Test the relay after sitting outside overnight and after running the engine 30 minutes.

An intermittent malfunction may be caused by a fault in the relay electrical circuit. Inspect the wiring harness and components for an intermittent condition. Refer to Intermittent Conditions .

Use the following relay cavity table in order to locate the correct cavities to probe during diagnosis. The table layout corresponds to the cavity layout of the relay block.

Relay Cavity Identification

Front of Vehicle

Switch Load

Battery Power Coil

Coil Control

Battery Power Load

Test Description

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

  1. This step verifies that the control module is providing voltage to the fuel pump relay.

    2.

  2. This step tests for an open in the ground circuit to the fuel pump relay.

Step

Action

Yes

No

Schematic Reference: Engine Controls Schematics

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

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2
  1. Turn ON the ignition, with the engine OFF.
  2. Command the fuel pump ON and OFF with a scan tool.

Does the fuel pump relay turn ON and OFF with each command?

Go to Step 3

Go to Step 4

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. 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 4

Go to Diagnostic Aids

4

  1. Turn OFF the ignition.
  2. Disconnect the fuel pump relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the control circuit of the fuel pump relay with a test lamp connected to a good ground.
  5. Command the fuel pump ON and OFF with a scan tool.

Does the test lamp turn ON and OFF when commanded?

Go to Step 5

Go to Step 6

5

  1. Connect a test lamp between the control circuit of the fuel pump relay and the ground circuit of the fuel pump relay.
  2. Command the fuel pump ON and OFF with a scan tool.

Does the test lamp turn ON and OFF when commanded?

Go to Step 7

Go to Step 9

6

Test the control circuit of the fuel pump relay for a short to voltage or an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 12

Go to Step 8

7

Test for shorted terminals and for poor connections at the fuel pump relay. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 12

Go to Step 10

8

Test for shorted terminals and for poor connections at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 12

Go to Step 11

9

Repair the open ground circuit of the fuel pump relay. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 12

--

10

Replace the fuel pump relay.

Did you complete the replacement?

Go to Step 12

--

11
  1. Replace the powertrain control module (PCM). Refer to Control Module References for replacement, setup, and programming.
  2. Perform the idle learn procedure. Refer to Idle Learn .

Did you complete the replacement?

Go to Step 12

--

12
  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 13

13

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