Circuit Description
The status of the fuel lift pump is monitored by the powertrain control module (PCM). This signal is also used in order to store a diagnostic trouble code (DTC) if the fuel pump relay is defective or if the fuel lift pump voltage is lost while the engine is running. There should be approximately 12 volts on circuit 120 during the glow plug cycle.
Conditions for Running the DTC
The fuel lift pump is commanded ON.
Conditions for Setting the DTC
| • | The difference between the ignition voltage and the fuel lift pump voltage is more than 4 volts. |
| • | The condition was met for 2 seconds. |
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | 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 emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Diagnostic Aids
This DTC will not check the fuel lift pump for operation.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 |
Important: Before clearing the DTCs, use the scan tool Capture Info to save the Freeze Frame/Failure Records for reference. The data in the control module is deleted once the Clear Info function is used. Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
Does the scan tool indicate the fuel lift pump voltage is near the specified value? | B+ | Go to Diagnostic Aids | Go to Step 3 | |
3 |
Does the scan tool display voltage at the specified value? | B+ | Go to Step 4 | Go to Step 5 |
4 |
Does the test lamp illuminate? | -- | Go to Step 6 | Go to Step 8 |
5 |
Did you perform a repair? | -- | Go to Step 17 | Go to Step 13 |
6 | Connect the J 35616-200 between terminal number B1 and terminal number A1 of the fuel pump relay harness connector. Does the test lamp illuminate? | -- | Go to Step 9 | Go to Step 7 |
7 | Repair the open fuel pump relay ground circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 17 | -- |
8 | Repair the open in the battery feed circuit to the fuel pump relay. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 17 | -- |
Does the J 35616-200 come ON during the glow plug cycle and then go OFF after the glow plug cycle is complete? | -- | Go to Step 10 | Go to Step 11 | |
10 |
Does the J 35616-200 come ON during the glow plug cycle and then go OFF after the glow plug cycle is complete? | -- | Go to Step 14 | Go to Step 15 |
11 | Check for an open or short to ground in the control circuit from the fuel pump relay harness connector terminal number B3 and the PCM. Was a problem found? | -- | Go to Step 12 | Go to Step 13 |
12 | Repair the open or short to ground in the fuel pump relay control circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 17 | -- |
13 |
Did you perform a repair? | -- | Go to Step 17 | Go to Step 14 |
14 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 17 | -- |
15 | Check for faulty connections at the fuel pump relay connector. Repair as necessary. Refer to Wiring Repairs in Wiring Systems. Did you perform a repair? | -- | Go to Step 17 | Go to Step 16 |
16 | Replace the fuel pump relay. Did you complete the replacement? | -- | Go to Step 17 | -- |
17 |
Does the scan tool indicate the diagnostic passed? | -- | Go to Step 18 | Go to Step 2 |
18 | Does the scan tool display any additional undiagnosed DTCs? | -- | System OK | |
