Troubleshooting the DFI System
Pull each connector [A] apart and inspect it for corrosion,
dirt, and damage.
If the connector is corroded or dirty, clean it carefully. If it
is damaged, replace it. Connect the connectors securely.
Check the wiring for continuity.
Use the wiring diagram to find the ends of the lead which
is suspected of being a problem.
Connect the hand tester between the ends of the leads.
Special Tool - Hand Tester: 57001-1394
Set the tester to the × 1 Ω range, and read the tester.
If the tester does not read 0 Ω, the lead is defective. Re-
place the lead or the main harness or the subharness.
If both ends of a harness [A] are far apart, ground [B] the
one end [C], using a jumper lead [D] and check the con-
tinuity between the end [E] and the ground [F]. This en-
ables to check a long harness for continuity. If the harness
is open, repair or replace the harness.
When checking a harness [A] for short circuit, open one
end [B] and check the continuity between the other end
[C] and ground [D]. If there is continuity, the harness has
a short circuit to ground, and it must be repaired or re-
Narrow down suspicious locations by repeating the con-
tinuity tests from the ECU connectors.
If no abnormality is found in the wiring or connectors, the
DFI parts are the next likely suspects. Check the part,
starting with input and output voltages. However, there is
no way to check the ECU itself.
If an abnormality is found, replace the affected DFI part.
If no abnormality is found in the wiring, connectors, and
DFI parts, replace the ECU.
FUEL SYSTEM (DFI) 3-25