Refer to Engine Controls Schematics .
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.
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
| • | The PCM illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive drive trip the diagnostic runs and fails. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the Failure Records store this information. If the diagnostic reports a failure on the second consecutive drive trip, the Freeze Frame records the operating conditions at the time of failure and updates the Failure Records. |
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 22°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.
-
This fuel pump can also be felt for a pulsing which will also determine if the fuel pump is working.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 |
Important: Before clearing any DTCs, use the Scan Tool Capture Info to save freeze frame and failure records for reference, as the Scan Tool loses data when using the Clear Info function. Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||
Does the Scan Tool indicate the fuel pump is operating? | -- | Go to Diagnostic Aids | ||
Is the voltage at the specified value? | B+ | |||
4 |
Is the voltage at the specified value? | B+ | ||
5 |
Was a problem found? | -- | ||
6 |
Was a problem found? | -- | ||
7 |
Was a problem found? | -- | ||
8 |
Is the test light ON? | -- | ||
9 | Repair the open in the battery feed circuit to the fuel pump relay. Is the action complete? | -- | -- | |
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? | -- | ||
11 | Repair the open fuel pump relay ground circuit. Is the action complete? | -- | -- | |
12 |
Does the test light come ON during the glow plug cycle and then go OFF after the glow plug cycle is complete? | -- | ||
13 |
Does the test light come ON during the glow plug cycle and then go OFF after the glow plug cycle is complete? | -- | ||
Check for an open or short to ground in the circuit from the fuel pump relay harness connector terminal number B3 and the PCM. Was a problem found? | -- | |||
15 | Repair the open or short to ground in the fuel pump relay control circuit. Is the action complete? | -- | -- | |
16 | Replace the PCM. Important: The new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | |
17 | Check for poor connections at the fuel pump relay connector. Was a problem found? | -- | ||
18 | Replace the fuel pump relay. Refer to Fuel Pump Relay Replacement . Is the action complete? | -- | -- | |
19 |
Does the Scan Tool indicate the diagnostic Passed? | -- | ||
20 | Does the Scan Tool display any additional undiagnosed DTCs? | -- | Go to the Applicable DTC Table | System OK |
