Inspection Procedure 3

Fuel Gauge does not Work.

Fuel Gauge Circuit:

Connectors:

CIRCUIT OPERATION
- The ignition switch (IG1) circuit is the power source for the fuel gauge.
- The resistance value fluctuates causing the circuit current to fluctuate when the fuel gauge unit the float moves up and down.
- The fuel gauge moves the needle by the circuit current.

TECHNICAL DESCRIPTION (COMMENT)
If the ignition switch (IG1) circuit is open, the gauge needle will not move at all. If the ground circuit is open, the gauge needle will move up to its extreme position.

TROUBLESHOOTING
- Malfunction of the fuel gauge unit.
- Malfunction of the combination meter (printed- circuit board or fuel gauge assembly)

DIAGNOSIS

Required Special Tool:
- MB991223: Harness Set

STEP 1. Check the speedometer operation.

Q: Does the speedometer work normally?

YES: Go to Step 2.

NO: Refer to Inspection Procedure 1.




STEP 2. Check the fuel gauge unit signal circuit at the fuel gauge unit connector E-30.
1. Disconnect the fuel gauge unit connector E-30.
2. Turn the ignition switch to "ON" position.
3. Measure the voltage between terminal 2 and ground.

Q: Is the voltage approximately 5 volts or more?

YES: Go to Step 5.

NO: Go to Step 3.







STEP 3. Check the fuel gauge unit connector E-30 and combination meter connector C-02 for damage.

Q: Are fuel gauge unit connector E-30 and combination meter connector C-02 in good condition?

YES: Go to Step 4.

NO: Repair or replace it. Refer to Harness Connector Inspection. The fuel gauge should work normally.







STEP 4. Check the harness wires between fuel gauge unit connector E-30 and combination meter connector C-02.

NOTE: After checking intermediate connector E-44, check the wire. If intermediate connector E-44 is damaged, repair or replace it. Refer to Harness Connector Inspection.

Q: Are the harness wires between fuel gauge unit connector E-30 and combination meter connector C-02 in good condition?

YES: Repair or replace the combination meter (printed- circuit board or fuel gauge assembly). The fuel gauge should work normally.

NO: Repair them. The fuel gauge should work normally.




STEP 5. Check the fuel gauge unit ground circuit at the fuel gauge unit connector E-30.
1. Disconnect the fuel gauge unit connector E-30.
2. Measure the resistance between terminal 3 and ground.

Q: Is the resistance less than two Ohms?

YES: Go to Step 8.

NO: Go to Step 6.




STEP 6. Check the fuel gauge unit connector E-30 for damage.

Q: Is fuel gauge unit connector E-30 in good condition?

YES: Go to Step 7.

NO: Repair or replace it. Refer to Harness Connector Inspection. The fuel gauge should work normally.




STEP 7. Check the harness wire between fuel gauge unit connector E-30 and ground.

Q: Is the harness wire between fuel gauge unit connector E-30 and ground in good condition?

YES: There is no action to be taken.

NO: Repair them. The fuel gauge should work normally.




STEP 8. Check the fuel gauge unit.
1. Remove the fuel gauge unit from the fuel tank.
2. Check resistance value between terminals 2 and 3 is at standard value when the fuel gauge unit float is at point "F" (highest) and point "E" (lowest).
3. Check that the resistance value changes smoothly when the float moves slowly between point "F" (highest) and "E" (lowest).

Q: Is the resistance 1 - 5 Ohms (at point "F") and 103 - 117 Ohms (at point "E")?

YES: Repair or replace the combination meter (printed- circuit board or fuel gauge assembly). The fuel gauge should work normally.

NO: Replace the fuel gauge unit. The fuel gauge should work normally.