Procedure 3 - Fuel Gauge Inoperative

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 pump module (fuel gauge unit)
- Malfunction of the combination meter (printed-circuit board or fuel gauge assembly)
- Damaged harness wires or connectors

DIAGNOSIS
Required Special Tool:
MB991223: Harness Set

STEP 1. Check the speedometer operation.
If the speedometer does not work normally, refer to Inspection Procedure 1.
If the speedometer works normally, go to Step 2.




STEP 2. Check the fuel pump module signal circuit at the fuel pump module connector D-17.
1. Disconnect the fuel pump module connector D-17 and measure at the harness side.
2. Turn the ignition switch to "ON" position.
3. Voltage between terminal 2 and ground.
- Voltage should be approximately 5 volts or more.
If less than approximately 5 volts, go to Step 3.
If approximately 5 volts or more, go to Step 5.







STEP 3. Check the fuel pump module connector D-17 and combination meter connector C-41 for damage.
If the fuel pump module connector D-17 and combination meter connector C-41 are damaged, repair or replace it. Refer to Harness Connector Inspection.
The fuel gauge should work normally.
If the connectors are in good condition, go to Step 4.










STEP 4. Check the harness wires between fuel pump module connector D-17 and combination meter connector C-41.

NOTE: After checking intermediate connector C-92, check the wire. If intermediate connector C-92 is damaged, repair or replace it. Refer to Harness Connector Inspection.

If the harness wires between fuel pump module connector D-17 and combination meter connector C-41 are damaged, repair them.
The fuel gauge should work normally.

If the harness wires are in good condition, repair or replace the combination meter (printed-circuit board or fuel gauge assembly).
The fuel gauge should work normally.




STEP 5. Check the fuel pump module ground circuit at the fuel pump module connector D-17.
1. Disconnect the fuel pump module connector D-17 and measure at the harness side.
2. Resistance between terminal 1 and ground.
- Should be less than 2 Ohms.
If open circuit, go to Step 6.
If less than 2 Ohms, go to Step 8.




STEP 6. Check the fuel pump module connector D-17 for damage.
If the fuel pump module connector D-17 is damaged, repair or replace it. Refer to Harness Connector Inspection.
The fuel gauge should work normally.
If the connector is in good condition, go to Step 7.




STEP 7. Check the harness wire between fuel pump module connector D-17 and ground.
If the harness wire between fuel pump module connector D-17 and ground is damaged, repair them.
The fuel gauge should work normally.




STEP 8. Check the fuel gauge unit.
1. Remove the fuel pump module from the fuel tank.
2. Check resistance value between terminals 2 and 1 is at standard value when the fuel gauge unit float is at point "F (highest) and point "E" (lowest).
- Resistance (point "F") should be 3 - 5 Ohms.
- Resistance (point "E") should be 110 - 112 Ohms.

3. Check that the resistance value changes smoothly when the float moves slowly between point "F" (highest) and "E" (lowest).
If resistance readings are not within specifications. Replace the fuel gauge unit.
The fuel gauge should work normally.

If normal, repair or replace the combination meter (printed-circuit board or fuel gauge assembly).
The fuel gauge should work normally.