65708

Description

First of all check damage of harness and terminals : Check terminals for contact resistance, corrosion and deformation.When battery power is NOT supplied to fuel filter heater although fuel filter heater circuit is normal, Inspect the fuel filter heater relay.

Diagnostic Procedure

Fuel filter heater relay coil resistance inspection

IG S/W 'OFF', ENGINE 'OFF'

Remove the fuel filter relay.

Before measuring resistance, you must calibrate(0Ω) the tester.

note

Refer to 'Multimeter calibration' of detail inspections (Equipment settings).

Measure the resistance between terminal '3' and terminal '5'.

■ Specification : 87Ω ± 10% ( 20℃ )

Fuel filter heater relay contacts inspection

Measure the resistance between terminal '1' and terminal '2'.

■ Specification : Discontinuity (Infinite Ω)

Actuate the Fuel filter heater relay after supplying power and ground to Fuel filter heater relay component terminal '3' and '5'.

■ Inspect operating sound in the Fuel filter heater relay when power is supplied.

Measure the resistance between Fuel filter heater relay component terminal '1' and '2'.

■ Specification : Continuity (below 1.0Ω)

Fuel filter relay visual inspection

※ If trouble symptom occurs intermittently although relay is operated well as above, Inspect the inside of the relay.

☞ Make sure of damage of the relay cover.

☞ Contact : Inspect contact connection and carbon deposit by spark.

☞ Coil : Inspect partial damage by coil short and enamel coating damage.

Symptom		Inspection procedure
Case1	● Relay coil resistance is high. (Open)	● Engine hard starting occurs or engine starting is impossible at cold starting because battery power is not supplied to fuel filter heater coil. (Diesel fuel is frozen) ● Replace the fuel filter heater relay.
Case2	● Relay coil resistance is low. (Short)	● Engine hard starting occurs or engine starting is impossible at cold starting because battery power is not supplied to fuel filter heater coil. (Diesel fuel is frozen) ● System is supplied by fuse is NOT operated because fuse is blown. (The fuse supplies battery power to fuel filter heater relay coil) ● Replace the fuel filter heater relay.
Case3	● Relay coil is normal. (Intermittent poor contact connection)	● Engine hard starting occurs or engine starting is impossible intermittently at cold starting because battery power is not supplied to fuel filter heater coil. (Diesel fuel is frozen) ● Replace the fuel filter heater relay.