Many malfunctions in the electrical system are caused by poor harness(s) and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
Check the following conditions:
Check for damaged harness and terminals: contact resistance, oxidation, bent or broken terminals.
Check for poor connection between ECM and component: backed out terminal, improper mating, broken locks or poor terminal to wire connection
Use a suitable male pin to ensure that contact in sockets is good. The pin should remain in position when pulled gently.
Has a problem been found?
YES
Repair as necessary and go to "Verification of Vehicle Repair" procedure
NO
Go to "Power Circuit Inspection" procedure
Remove the fuel pump relay.
Ignition "ON" & Engine "OFF".
Measure the voltage between terminal 6 of the fuel pump relay harness connector(Fuel pump relay) and chassis ground.
Measure the voltage between terminal 18 of the fuel pump relay harness connector(Fuel pump relay) and chassis ground.
Specification : Approx. B+
Is voltage display near the specified value?
YES
Go to "Control Circuit Inspection"
NO
Check for an open or short to ground in the power supply circuit. Repair as necessary and go to "Verification of Vehicle Repair" procedure.
Ignition "OFF" & Relay connector : Disconnected
Measure resistance between terminal 20 of the relay harness connector(Fuel pump relay) and chassis ground
Specification : Infinite
Is resistance within specification?
YES
Go to next step.
NO
Repair as necessary and go to "Verification of Vehicle Repair" procedure.
With Ignition "OFF", disconnect relay and ECM connectors
Ignition "ON" and Engine "OFF"
Measure voltage between terminal 20 of the relay harness connector(Fuel pump relay) and chassis ground
Specification : Approx 0V
Is voltage within specification?
YES
Go to next step.
NO
Repair as necessary and go to "Verification of Vehicle Repair" procedure.
With Ignition "OFF", disconnect relay and ECM connectors
Measure resistance between terminals 20 of the relay harness connector(Fuel pump relay) and ECM(10/C23-4)
Specification : Approx 0Ω
Is resistance within specification?
YES
Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure
NO
Repair as necessary and go to "Verification of Vehicle Repair" procedure.
