Circuit Description
When you turn the ignition switch to the on position, the PCM activates the in-tank fuel pump. The fuel pump remains on as long as the PCM receives reference pulses from the electronic ignition system. If there are no reference pulses, the PCM turns the fuel pump off after about 2-3 seconds. The PCM controls the fuel pump relay by applying B+ to the control circuit via an internal switch called a driver. The primary function of the driver is to supply a voltage to the fuel pump relay. The driver has a fault line which the PCM monitors. When the PCM commands the fuel pump on, the voltage of the control circuit should be high (near battery voltage). When the PCM commands the control circuit to the fuel pump OFF, the voltage potential of the circuit should be low (near 0 volts). This DTC sets when the PCM detects the fuel pump control circuit is shorted to ground.
Conditions for Setting the DTC
| • | Engine speed greater than 600 RPM |
| • | System voltage is between 6.0 volts and 16 volts |
| • | The PCM detects that the commanded state of the driver and the actual state of the control circuit do not match |
| • | All the above conditions present for a minimum of 10 seconds. |
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Freeze Frame and/or Failure Records. |
Conditions for Clearing the MIL/DTC
| • | A last test failed, or the current DTC, clears when the diagnostic runs and does not fail. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if failures are not reported by this or any other emission related diagnostic. |
| • | Use a scan tool in order to clear the MIL/DTC. |
Diagnostic Aids
Fuel Pump Relay Underhood Electrical Center Terminal Identification | |||
|---|---|---|---|
Front of Vehicle | |||
Left Side of Vehicle | Ground | Ignition | Right Side of Vehicle |
Load | Control | ||
| • | The following may cause an intermittent: |
| - | Poor connections: Check for adequate terminal tension. Refer to Body and Accessories/Wiring Systems for proper procedure. |
| - | Corrosion |
| - | Mis-routed harness |
| - | Rubbed through wire insulation |
| - | Broken wire inside the insulation |
| • | This DTC will not report a pass. The scan tool status for this DTC will never report a pass so it will appear that the diagnostic never runs. This will cause the MIL to remain ON until a DTC clear command or battery disconnect occurs. |
| • | Using the Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also help determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This will isolate when the DTC failed. For an intermittent condition, refer to Symptoms . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Listen for an audible click when the relay operates. Command both the ON and the OFF states. Repeat the commands as necessary.
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This check can detect a partially shorted coil which would cause excessive current flow. Leaving the circuit energized for 2 minutes allows the coil to warm up. When warm, the coil may short (goes above 0.75 Amp).
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Identify and test the relay coil terminals in order to avoid improper diagnosis.
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If you do not find any trouble in the control circuit or the connection at the PCM, the PCM may be malfunctioning. However, this is an extremely unlikely failure. Before replacing the PCM, inspect for poor connections at the PCM harness connectors.
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This DTC will not report a pass. The scan tool status for this DTC will never report a pass. The scan tool will only display when the diagnostic fails. The repair is not complete if the scan tool indicates that the diagnostic ran and failed.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
Does the fuel pump relay turn ON and OFF when commanded? | -- | |||
Does the current draw measure less than the specified value shown (but not 0)? | 0.75A | Go to Diagnostic Aids | ||
4 |
Does the DMM display infinite resistance? | -- | ||
Does the test lamp turn ON and OFF when commanded? | -- | |||
6 | Check the resistance from the fuel pump relay ground circuit at the underhood electrical center to the battery ground using the DMM J 39200 . Is the resistance within the specified range? | 0-5ohms | ||
7 |
Does the relay operate? | -- | ||
8 | Check the connections at the relay. Did you find and correct the condition? | -- | ||
9 | Repair the open fuel pump relay ground circuit. Is the action complete? | -- | -- | |
10 | Repair the fuel pump relay control circuit. Is the action complete? | -- | -- | |
11 | Replace the relay. Is the action complete? | -- | -- | |
|
Important:: Program the replacement PCM. Refer to Powertrain Control Module/Throttle Actuator Control Module Replacement . Replace the PCM. Is the action complete? | -- | -- | ||
Does the scan tool indicate that this test failed? | -- | |||
14 | Select the Capture Info option and the Review Info option using the scan tool. Are any DTCs displayed that you have not diagnosed? | -- | Go to the applicable DTC table | System OK |
