Circuit Description
The engine control module (ECM) provides ignition 1 voltage to the coil side of the fuel pump relay. When you turn ON the ignition switch, the ECM energizes the fuel pump relay, which applies power to the fuel pump. The ECM applies a low current signal of approximately 7 volts to the fuel pump relay control circuit with the key ON and the engine OFF. The ECM uses this signal to detect the integrity of the fuel pump relay control circuit. The ECM enables the fuel pump relay as long as the engine is cranking or running, and crankshaft reference pulses are received. If no crankshaft reference pulses are received, the ECM de-energizes the fuel pump relay after 2 seconds. The ECM monitors the voltage on the fuel pump relay control circuit. If the ECM detects a low voltage condition on the fuel pump relay control circuit a fuel pump relay control DTC sets.
Conditions for Running the DTC
| • | The engine speed is more than 40 RPM. |
| • | The system voltage is between 8-18 volts. |
Conditions for Setting the DTC
| • | The ECM detects an incorrect voltage on the control circuit of the fuel pump relay . |
| • | The condition exists for less than 1 second. |
Action Taken When the DTC Sets
| • | The control module stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records. |
| • | The driver information center, if equipped, may display a message. |
Conditions for Clearing the DTC
| • | A current DTC Last Test Failed clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
| • | Clear the DTC with a scan tool. |
Diagnostic Aids
Fuel Relay Right Rear Bussed Electrical Center Terminal Identification | |||
|---|---|---|---|
Front of vehicle | |||
Left side of vehicle | Control | Fuel pump supply | Right side of vehicle |
-- | Ignition 1 voltage | Ground | -- |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step verifies that the ECM is providing voltage to the fuel pump relay.
-
This step tests for a short to ground in the control circuit to the fuel pump relay.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views | |||
1 | Did you perform the Diagnostic System Check-Engine Controls? | Go to Step 2 | |
2 |
Important: An audible click should be heard. Does the fuel pump relay turn ON and OFF with each command? | Go to Step 3 | Go to Step 4 |
3 |
Did the DTC fail this ignition? | Go to Step 4 | Go to Intermittent Conditions |
Does the test lamp turn ON and OFF with each command? | Go to Step 6 | Go to Step 5 | |
Test the control circuit of the fuel pump relay 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 8 | Go to Step 7 | |
6 | Replace the fuel pump relay. Did you complete the replacement? | Go to Step 8 | -- |
7 | Replace the engine control module (ECM). Refer to Engine Control Module Replacement . Did you complete the replacement? | Go to Step 8 | -- |
8 |
Did the DTC fail this ignition? | Go to Step 2 | Go to Step 9 |
9 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | System OK | |
