Inspection Procedure 3

Fuel gauge does not work.

Fuel Gauge Circuit:

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 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)

DIAGNOSIS

Required Special Tool:
MB991223: Harness Set

STEP 1. Check the fuel gauge by observing the other meter.
Check to see that the speedometer, tachometer and water thermometer operate normally.

Q: Do all other meters operate?

YES : Go to Step 2.
NO : Refer to Inspection Procedure 1.

STEP 2. Check the fuel pump module signal circuit at fuel
pump module connector D-17 by backprobing.




1. Do not disconnect fuel pump module connector D-17.
2. Turn the ignition switch to ON position.




3. Measure the voltage between terminal 2 and ground by backprobing.

Q: Is the voltage approximately 5 volts or more?

YES: Go to Step 5.
NO: Go to Step 3.







STEP 3. Check fuel pump module connector D-17 and combination meter connector C-102 for damage.

Q: Are fuel pump module connector D-17 and combination meter connector C-102 in good condition?

YES: Go to Step 4.
NO: Repair or replace the connector(s). Refer to Harness Connector Inspection. The fuel gauge should work normally.







STEP 4. Check the wiring harnesses between fuel pump module connector D-17 (terminal 2) and combination meter connector C-102 (terminal 43).

NOTE: Also check intermediate connector C-210. If intermediate connector C-210 is damaged, repair or replace the connector as described in Harness Connector Inspection.




Q: Are the wiring harnesses between fuel pump module connector D-17 (terminal 2) and combination meter connector C-102 (terminal 43) 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 the wiring harness(es). The fuel gauge should work normally.

STEP 5. Check the fuel pump module ground circuit at the fuel pump module connector D-17 by backprobing.




1. Do not disconnect the fuel gauge unit connector D-17.




2. Measure the resistance value between terminal 1 and ground.
- The measured value should be 2 ohms or less.

Q: Does the measured resistance value correspond with this range?

YES: Go to Step 8.
NO: Go to Step 6.




STEP 6. Check fuel pump module connector D-17 for damage.

Q: Is fuel gauge unit connector D-17 in good condition?

YES: Go to Step 7.
NO: Repair or replace the connector. Refer to Harness Connector Inspection. The fuel gauge should work normally.




STEP 7. Check the wiring harness between fuel pump module connector D-17 and ground.

Q: Is the wiring harness between fuel pump module connector D-17 and ground in good condition?

YES: There is no action to be taken.
NO: Repair the wiring harness. The fuel gauge should work normally.




STEP 8. Check the fuel gauge unit.
1. Remove the fuel pump module from the fuel tank (Refer to 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).

Standard value:
- Point "F": 3 - 5 ohms
- Point E: 110 - 112 ohms

3. Check that the resistance value changes smoothly when the float moves slowly between point F (highest) and E (lowest).

Q: Is the resistance 3 - 5 ohms (at point "F") and 110 - 112 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.