Lexus RX (RX 350L, RX450h) 2016-2024 Repair Manual: Precaution

PRECAUTION

PRECAUTION FOR DISCONNECTING CABLE FROM NEGATIVE BATTERY TERMINAL

NOTICE:

When disconnecting the cable from the negative (-) battery terminal, initialize the following systems after the cable is reconnected.

PRECAUTION FOR REPLACING COMBINATION METER ASSEMBLY

When replacing the combination meter assembly, always replace it with a new one. If a combination meter assembly which was installed to another vehicle is used, the information stored in it will not match the information from the vehicle and a DTC may be stored.

FUEL RECEIVER GAUGE OPERATION

(a) OPERATION

The combination meter assembly uses the fuel sender gauge assembly to detect the amount of fuel remaining in the fuel tank assembly. There are 2 types of fuel sender gauge assembly available. One type detects the amount of fuel remaining using a variable resistor and other type detects the amount of fuel remaining using a Hall IC.

(1) Variable resistor type:

The fuel sender gauge assembly has a variable resistor whose resistance changes according to the amount of fuel remaining. The fuel sender gauge assembly receives voltage from the combination meter assembly and changes the voltage based on the resistance that changes according to the amount of fuel remaining in the fuel tank assembly. The combination meter assembly detects the voltage between the variable resistor and the resistor in the combination meter assembly and operates the fuel receiver gauge.

(2) Hall IC type:

The Hall IC built into the fuel sender gauge assembly changes the output voltage according to the amount of fuel remaining. The combination meter assembly detects the voltage output from the fuel sender gauge assembly and operates the fuel receiver gauge.

(b) FUEL RECEIVER GAUGE READING

(1) During normal driving:

As the fuel level in the fuel tank assembly changes when driving on a hill or applying the brakes, the fuel receiver gauge reading is updated according to the fuel injection volume during normal driving. However, as the fuel injection volume measurement has a margin of error, the value is indicated after correction by input values from the fuel sender gauge assembly.

(2) During refueling:

The fuel level in the fuel tank assembly rises rapidly when fuel is added. If the averaging process that is used during normal driving is used in this case, the fuel receiver gauge reading cannot be updated promptly. Therefore, when it is judged that fuel is being added to the vehicle based on the shift lever position and changes in the fuel level, output values from the fuel sender gauge assembly is immediately reflected in the fuel receiver gauge reading. This control is called refueling judgment.

(c) REFUELING JUDGMENT CONDITIONS

NOTICE:

Add fuel with the engine switch off to ensure safety and to enable refueling judgment so that an appropriate fuel receiver gauge reading is obtained. If it is necessary to add fuel with the engine switch on (IG), move the shift lever to P or N.

(1) Normal judgment condition (When normal refueling method is used)

With the engine switch off, the fuel sender gauge assembly detects a change of 5.0 liters (5.3 US qts, 4.4 Imp. qts) or more in the fuel level.

(2) Other judgment conditions (When other refueling method is used)

Any of the following conditions is met:

(d) PRECAUTION FOR REFUELING

The fuel sender gauge assembly cannot detect changes in the fuel level within certain ranges (around points E and F). Therefore, even if 5.0 liters (5.3 US qts, 4.4 Imp. qts) or more of fuel is added, refueling judgment may not be performed and the fuel receiver gauge reading may not change when fuel level is within such ranges.

(e) FORCED RESET OF FUEL RECEIVER GAUGE

When driving at 1.8 km/h (1 mph) or more, if the output values from the fuel sender gauge assembly is different from the fuel receiver gauge reading by 15.0 liters (15.9 US qts, 13.2 Imp. qts) or more for approximately 2 minutes, output values from both gauge assemblies are immediately reflected in the fuel receiver gauge reading to compensate for a situation when refueling judgment cannot be made.