E020 Part 1 of 3

Code E020:

Fuel Pump Circuit:

DESCRIPTION:

The fuel pump receives power from CKT 120 through either the fuel pump relay or the oil pressure switch. The PCM/ECM energizes the fuel pump relay for 2 seconds at key on to provide fuel pressure for starting. After the 2 second fuel pump prime, the PCM/ECM will not power the fuel pump relay until distributor reference pulses are received indicating that the engine is turning (crank or run). The oil pressure switch is provided as a back up to the fuel pump relay. Normal operating engine oil pressure will close the normally open switch contacts in the oil pressure sensor, providing a connection between CKT 239 and 120. If a relay fault occurs, the engine will continue to run as the oil pressure switch powers the fuel pump. A vehicle with the relay inoperative will crank until oil pressure builds (oil telltale off) then start and run as the switch provides power to the fuel pump. The PCM/ECM monitors voltage on the fuel pump power CKT 120 to detect fuel pump voltage supply faults. Code E020 will set when the PCM/ECM sees the fuel pump not energized (0 volts on the feedback) with the engine cranking or running. The code is designed to detect a fuel pump relay fault; relay not powering the fuel pump.

TEST CONDITIONS:

1. Engine speed greater than or equal to 24 RPM.

FAILURE CONDITIONS:

Fuel pump feedback voltage 2 volts or less for 1 second.

ACTION TAKEN:

1. PCM/ECM turns on "SERVICE ENGINE SOON" telltale.

NOTES ON FAULT TREE:

1. Checking for engine to start with fuel pump powered through the fuel pump relay. If car does not start, go to code E020 part 2 of 3.

2. 0 volts with engine running indicates an open from the fuel pump power circuit to PCM/ECM - the fuel pump relay is not at fault.

NOTE ON INTERMITTENTS:

If code E20 is stored as history, unplug the oil pressure switch, start the engine, and allow to idle. Manipulate affected wiring, check the relay for proper installation into socket. If the fault is induced, the engine will stall, code E020 will set. If code E020 sets without an engine stall, the cause is an intermittent open CKT 120 between PCM/ECM pin E13 and splice to the fuel pump relay.