JP4123979B2 - Tire pressure monitoring system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tire pressure monitoring system, and more particularly to a tire pressure monitoring system that individually identifies a plurality of tires and monitors their air pressures.
[0002]
[Prior art]
[Patent Document 1]
JP, 2000-103209, A The pressure switch which detects tire air pressure, and the electromagnetic resonance circuit which changes with this pressure switch are provided in the tire side, and the resonance state of this resonance circuit is detected by the device provided in the body side A tire pressure detecting device is conventionally known. Then, by registering the individual ID (identification code) of the transmitter attached to each tire in the receiver installed in the vehicle, the monitoring result of the tire pressure for each individual tire, the state of the pressure switch to decide.
[0003]
[Problems to be solved by the invention]
For example, Patent Document 1 discloses an ID registration method for a conventional tire pressure monitoring system.
In this example, the ID registration switch of the device provided on the vehicle body side is turned on, and the operator operates the air valve of the tire to be registered to change the pressure inside the tire, so that it is attached to the tire. ID is registered by causing the transmitter to detect the internal pressure change of the tire and forcibly transmitting the ID signal and the air pressure data signal from the transmitter.
[0004]
However, in this method, the operator registers the ID by forcibly transmitting the ID by changing the internal pressure of each tire to be registered in the order of the left front wheel, the left rear wheel, the right front wheel, and the right rear wheel, for example. It is necessary to operate the tire air valve one by one.
[0005]
Furthermore, since the ID of the transmitter to be registered corresponds to the tire position of the left front wheel, left rear wheel, right front wheel, and right rear wheel in the memory ID storage position, the tire at the specific wheel position is selected. In the case of replacement with a new one or replacement of a wheel position of a tire, an operator has to confirm the correspondence between the ID of the transmitter and the ID storage position of the memory.
Therefore, it is a complicated procedure in which the operator checks the ID storage position of the memory with the display device at the driver's seat and operates the tire air valve.
[0006]
In order to solve the above-mentioned problems, the present invention does not require complicated procedures such as an operator operating a tire air valve or confirming a tire mounting wheel position and an ID storage position of a memory, and ID registration is not required. An object is to provide a possible tire pressure monitoring system.
[0007]
[Means for Solving the Problems]
For this reason, the present invention includes a first communication device that transmits detected air pressure data for each tire of each wheel, receives a signal of air pressure data by a second communication device installed on the vehicle body side, In the monitoring device that determines whether or not there is an abnormality and displays the result, the first communication device includes first receiving means for receiving a control signal from the second communication device, and air pressure data in accordance with the control signal. The first communication unit has a first transmission means for transmitting a signal or a signal of a unique identification code for each first communication device, and the second communication device is connected to the first communication device through a transmission antenna installed near each wheel. Second transmitting means for transmitting a control signal, second receiving means for receiving a pneumatic data signal and an identification code signal from the first communication device, storage means for storing the identification code, and vehicle speed detecting means It has the door, and second transmitting means The second receiving means is shared with the keyless system, the transmitting antenna of the second transmission means are installed in each door of the vehicle.
Furthermore, the second communication device has control means for controlling transmission start and transmission stop of the first transmission means via the second transmission means, and when the vehicle speed is less than a predetermined value, the first communication The transmission from the device was stopped.
[0008]
【The invention's effect】
According to the present invention, the control means of the second communication device installed on the vehicle body side selects one wheel position and selects it via the transmission antenna of the second transmission means installed near the selected wheel position. It is possible to send a control signal only to the first communication device of the tire at the wheel position and transmit the signal from the first communication device.
[0009]
As a result, the second communication device can receive transmission data including an identification code from only the first communication device at one wheel position, and can recognize the wheel position. Therefore, the identification code of the first communication device of the tire at each wheel position can be easily associated with the wheel position and registered in the storage means.
In addition, since the transmission from the first communication device is stopped when the vehicle speed is less than the predetermined value, it is possible to suppress the power consumption of the first communication device. The second communication device can be easily realized only by changing the programming of the microcomputer in the keyless system. As a result, an inexpensive tire pressure monitoring system can be realized in terms of cost .
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a block diagram of a tire pressure monitoring system integrated with a smart-keyless system. FIG. 2 is a block diagram of a pneumatic data transmission device mounted on a tire.
The feature of the present embodiment is that, as will be described in detail below, the smart keyless system uses a low-frequency transmitter and a high-frequency receiver mounted as vehicle body side devices, and a pneumatic data transmission device for each tire It is in the place where the body side equipment of the smart keyless system is also used for communication.
[0011]
As shown in FIG. 1A, the pneumatic data transmitter (TP: transponder) 2 (2a, 2b) is provided on the tire air valves of the front wheels 21 (21R, 21L) and the rear wheels 22 (22R, 22L). 2c, 2d).
As shown in FIG. 1A, the vehicle body side device includes a switch 6 provided in each of the control unit 1, the front doors 23R and 23L, the rear doors 24R and 24L, and the trunk 25 installed in the passenger compartment. It consists of.
[0012]
The control unit 1 includes a low frequency transmitter (LF) 9, a high frequency receiver (RF) 10, a microcomputer (CPU) 11, a memory 12, and a display device 3.
The low-frequency transmitter 9 has a transmission antenna near each wheel position. Specifically, the low-frequency transmitter antenna 7 is arranged at the front doors 23R and 23L and the rear doors 24R and 24L. In addition, each of the passenger compartment and the trunk 25 has low-frequency transmitter antennas 5 and 7. The low-frequency transmitter 9 can choose to transmit from all these antennas at the same time or from only certain antennas.
[0013]
The high frequency receiver 10 has a high frequency receiver antenna 8.
The low frequency transmitter 9, the high frequency receiver 10 and the memory 12 are connected to the microcomputer 11. Further, each switch 6 is connected to the microcomputer 11.
A card 30 held by a passenger of the smart keyless system shown in FIG. 1B incorporates a low frequency receiver (LF receiver) 31 and a high frequency transmitter (RF transmitter) 32.
[0014]
As shown in FIG. 2, the air pressure data transmitting device 2 has a built-in air pressure sensor 16 that measures tire air pressure and a high-frequency transmitter (RF transmitter) 14 that transmits air pressure data with radio waves having a frequency of about several hundred MHz. .
The pneumatic data transmission device 2 includes a low-frequency receiver (LF receiver) 15 that receives a radio wave of a control signal having a frequency of about several hundred kHz transmitted from the outside, and a high-frequency transmitter 14 according to the control signal. Is incorporated.
The high frequency transmitter 14, the low frequency receiver 15 and the air pressure sensor 16 are connected to a microcomputer 17.
[0015]
The air pressure data transmission device 2 incorporates a battery (not shown) as a power source for the low-frequency receiver 15, the high-frequency transmitter 14, and the microcomputer 17 described above.
The microcomputer 17 sets a signal obtained by digitizing the signal of the air pressure sensor 16 and an ID (identification code) unique to each air pressure data transmission device 2 in accordance with the control signal received by the low frequency receiver 15 to set the high frequency Transmission is performed via the transmitter 14, only ID is transmitted, or transmission is stopped.
The transmission of the set of air pressure data and ID is performed in a normal transmission mode at regular intervals. When a change in air pressure of a predetermined value or more is detected, the air pressure data and the ID are transmitted at that time.
[0016]
The microcomputer 11 of the control unit 1 transmits a transmission start command or a transmission stop command to the air pressure data transmission device 2 via a low frequency transmitter 9 with a radio wave of about several hundred kHz.
Further, the microcomputer 11 receives the ID signal and the air pressure data signal from the air pressure data transmitting device 2 via the high frequency receiver 10 and determines whether the received signal is from the air pressure data transmitting device 2 of the own vehicle. In the case of a vehicle signal, it is determined whether or not there is an abnormality in the air pressure of each tire.
[0017]
Furthermore, in the registration or confirmation mode of the ID of the air pressure data transmission device 2 of the own vehicle, it is determined whether or not the ID of each tire is stored in the memory 12, that is, whether or not it is registered. The ID is stored in the memory 12.
The memory 12 is a nonvolatile memory, for example, an EEPROM.
In the normal tire pressure monitoring mode, the microcomputer 11 displays the tire pressure of each wheel on the display device 3. If there is an abnormality in the tire air pressure or if there is an abnormality in the ID registration confirmation result, the content of the abnormality is displayed on the display device 3 together with the wheel position.
[0018]
When functioning as a smart keyless system, when the occupant operates the switch 6 of any door or trunk, the microcomputer 11 detects the location of the operated switch 6 and detects the location of the low switch provided in the door or trunk. A card ID transmission request signal is transmitted from the frequency transmitter antenna 7 to the card 30. On the other hand, the card 30 receives the ID transmission request signal by the low frequency receiver 31 and transmits the card ID information from the high frequency transmitter 32 by radio waves of about several hundred MHz.
[0019]
The high frequency receiver 10 receives the radio wave of the card ID signal from the card 30 and inputs the ID to the microcomputer 11. The microcomputer 11 determines whether or not the card ID matches the passenger's card ID registered in advance in the vehicle and stored in the memory 12. If they match, an unlock signal is output to the front doors 23R, 23L, the rear doors 24R, 24L, or the lock device of the trunk 25 to unlock them.
[0020]
FIG. 3 is a flowchart showing the overall flow of registration or confirmation of the ID of the pneumatic data transmission device, and FIG. 4 is a detailed flowchart showing the flow of registration or confirmation of the ID of the pneumatic data transmission device of each tire. .
Here, a general passenger car will be taken as an example, and the discussion will proceed assuming that the initial registration of the ID of the air pressure data transmission device 2 of each tire has already been completed at the factory shipment stage.
In the flowchart, the pneumatic data transmission device 2 is abbreviated as TP (transponder).
[0021]
When the passenger gets on and turns on the ignition switch, the ID registration or confirmation mode starts.
In step 101, the microcomputer 11 resets the registration / confirmation processing repetition counter N to zero as initialization of ID registration or confirmation processing of the pneumatic data transmission device (TP) 2.
In step 102, the microcomputer 11 resets the ID registration or the confirmed flag FLAG (M) of each wheel position M (M = 1 to 4) to zero as initialization at each registration / confirmation processing repetition.
[0022]
In step 103, the microcomputer 11 registers or confirms the ID of the pneumatic data transmission device 2a for the right front wheel (M = 1). When the ID of the tire pressure data transmitting device 2 corresponding to the wheel position M can be registered or confirmed, FLAG (M) = 1.
In step 104, registration or confirmation of the ID of the pneumatic data transmission device 2b for the left front wheel (M = 2) is performed.
[0023]
Similarly, in steps 105 and 106, registration or confirmation of the IDs of the pneumatic data transmission devices 2c and 2d for the right rear wheel (M = 3) and the left rear wheel (M = 4) is performed.
In step 107, 1 is added to the registration / confirmation repetition counter N.
In step 108, it is checked whether or not the IDs of the pneumatic data transmitting devices 2 at the four wheel positions have been confirmed.
[0024]
That is, if FLAG (M) = 1 for each of M = 1 to 4, and all the stored IDs are different, it is determined that four IDs have been confirmed.
If the ID cannot be confirmed even with the tire pressure data transmission device 2 at one wheel position, the routine proceeds to step 109. If the IDs of the air pressure data transmission devices 2 for all wheel positions have been confirmed, the process proceeds to step 111.
[0025]
In step 109, it is determined whether the registration / confirmation repetition counter N has exceeded a predetermined upper limit value NL. If exceeded, the process proceeds to step 110, and ID registration or confirmation work is terminated. If not, return to step 102 and repeat.
Note that the upper limit of the registration / confirmation repetition count N may be about 2. This repetition is a slight communication trouble between the pneumatic data transmitter 2 and the control unit 1, and the ID of one of the pneumatic data transmitters 2 can be confirmed. Even in the absence of the ID, the ID is surely completed.
[0026]
In step 110, as an error process, it is displayed on the display device 3 that the ID of the tire pressure data transmitting device 2 at the wheel position M cannot be confirmed.
After step 110, the process proceeds to step 111.
In step 111, the registration / confirmation repetition counter N is reset to zero.
In step 112, the air pressure data transmission device 2 for all the wheels is requested to start transmission, the mode is shifted to the normal air pressure monitoring mode, and the ID registration or confirmation processing of the air pressure data transmission device 2 is ended.
Thereafter, the air pressure data transmission device 2 that has been instructed to stop transmission during the ID registration or confirmation work described later also starts transmission for normal tire pressure monitoring.
[0027]
Next, details of the registration or confirmation work of the ID of the tire pressure data transmitting device in each of steps 103 to 106 will be described with reference to the flowchart of FIG.
Here, it is assumed that the ID of the tire air pressure data transmission device 2c at the position of the right rear wheel 22R (M = 3) is to be registered or confirmed.
In step 201, the microcomputer 11 transmits a signal for stopping transmission of air pressure data and ID from the low frequency transmitter 9 to the air pressure data transmitting device 2 at all wheel positions via all the low frequency transmitter antennas 7.
[0028]
This is because all the radio waves transmitted from each air pressure data transmitting device 2 are received by the high frequency receiver antenna 8, so that each air pressure data transmitting device 2 has a one-to-one correspondence with the wheel position when in the transmitting state. This is because it cannot be removed.
In step 202, the microcomputer 11 controls the low frequency transmitter 9 to transmit the air pressure data and the ID from the low frequency transmitter antenna 7 of the right rear door 24R close to the right rear wheel 22R to the air pressure data transmitting device 2c. A transmission start signal is transmitted.
As a result, only the air pressure data transmitting device 2c starts transmitting air pressure data and ID in a normal procedure. The high frequency receiver 10 receives the air pressure data signal and the ID signal from the air pressure data transmitting device 2 c and inputs the signals to the microcomputer 11.
[0029]
In step 203, the microcomputer 11 determines whether the ID transmitted together with the air pressure data from the air pressure data transmitting device 2c matches the ID corresponding to the wheel position M = 3 registered and stored in the past. To check.
If they coincide with each other, the process proceeds to step 212, where FLAG (3) = 1 is set, and the registration or confirmation processing of the ID of the pneumatic pressure data transmission device 2c at this wheel position (M = 3) is terminated.
If not, the process proceeds to step 204.
[0030]
In step 204, a transmission stop signal for stopping transmission of air pressure data and ID is transmitted from all the low frequency transmitter antennas 7 of the low frequency transmitter 9 to the air pressure data transmitting device 2 of all the wheels. Here, only a transmission stop request to the air pressure data transmission device 2c is required, but a transmission stop request is made to the air pressure data transmission device 2 for all the wheels just in case.
In step 205, an ID transmission request signal is transmitted from the low frequency transmitter antenna 7 of the right rear door 22R to the pneumatic data transmitting device 2c.
[0031]
In step 206, the timer starts counting. This timer is used to register or confirm the ID of the pneumatic data transmitting device 2 at the next wheel position by determining whether or not the reception of the ID is completed within a predetermined time Tmax, for example, within 2 to 3 seconds. .
In response to the ID transmission request, only the pneumatic data transmission device 2 c transmits the ID, receives it by the high frequency receiver 10, and inputs it to the microcomputer 11. After step 206, the process proceeds to step 207.
[0032]
In step 207, it is checked whether or not an ID is received from the air pressure data transmission device 2c. If the ID can be received, the process proceeds to step 209.
If the ID cannot be received, the process proceeds to step 208. If the timer is within the predetermined time Tmax, the process returns to step 207. If the timer is equal to or longer than the predetermined time Tmax, the process proceeds to step 211.
[0033]
In step 209, the ID of the received air pressure data transmission device 2c matches the ID corresponding to the wheel position M (= 3) stored in the memory 12, and the wheel position of M = 3 in the memory 12 regardless of whether or not they match. Store and register correspondingly.
In step 210, FLAG (3) = 1 is set. After step 210, the process proceeds to step 211.
In step 211, the timer is reset and the registration or confirmation process of the ID of the air pressure data transmitting device 2 at the wheel position M (= 3) is ended.
[0034]
When the time limit Tmax of the timer is reached without receiving the ID of the air pressure data transmitting device 2c, FLAG (3) = 0 remains, and in step 108 of the flowchart of FIG. 3, the air pressure at the wheel position M = 3 is maintained. It is detected that the ID of the data transmission device 2c has not been confirmed, and ID registration / confirmation is repeated.
[0035]
In the flowchart of FIG. 4, when the ID stored in the memory 12 corresponding to the wheel position matches the received ID in step 203, the received ID is overwritten so as to correspond to the wheel position M. After storing and setting FLAG (M) = 1, the registration or confirmation process may be terminated.
[0036]
In the above description, it has been described that the initial registration of the pneumatic pressure data transmission device 2 of the tire at each wheel position has already been completed at the factory shipment stage, but the ID of the pneumatic data transmission device 2 at the new vehicle shipment stage at the factory. If you are registering for the first time, you may use a different procedure.
For example, the display device 3 is provided with a selection switch for “initial ID registration” at the new vehicle shipment stage and “ID registration / confirmation” after purchase.
[0037]
Then, at the time of initial ID registration, “initial ID registration” is selected, and steps 201, 202, 203, 204 and step 212 of FIG. 4 are deleted from the flowcharts of FIGS. 3 and 4 described above. By causing the microcomputer 11 to execute this separate procedure, the IDs of the pneumatic data transmission devices 2 at all the four wheel positions are registered in a short time when the initial ID is registered.
When the purchaser registers or confirms the ID of the air pressure data transmission device 2 after exchanging the tire, “ID registration / confirmation” is selected and the microcomputer 11 is caused to execute it according to the flowcharts shown in FIGS.
[0038]
Furthermore, the control for extending the life of the internal battery of the pneumatic data transmission device in the normal pneumatic data transmission mode in the embodiment will be described based on the flowchart of FIG.
A vehicle speed sensor 33 is connected to the microcomputer 11 of the control unit 1 as shown in FIG.
The microcomputer 11 completes the ID registration or confirmation work of the pneumatic data transmitting device 2 of all the wheels by turning on the ignition switch as shown in the flowchart of FIG. The air pressure data transmitting device 2 is requested to start transmission so as to transmit in the normal air pressure monitoring mode.
[0039]
Step 301 corresponds to step 112 described above.
In step 302, the microcomputer 11 determines whether the set of the received ID signal and air pressure data signal is that of the own vehicle or which wheel position is the identification code, and the air pressure data transmitting device 2 of the own vehicle. It is determined whether or not the air pressure of the signal from is within a predetermined setting range.
When it deviates from the predetermined setting range, the wheel position and the air pressure abnormality are displayed on the display device 3.
In step 303, if the vehicle speed signal from the vehicle speed sensor is less than the predetermined speed VA, for example, if the vehicle speed is less than 5 km / h, the process proceeds to step 304. Otherwise, the process returns to step 302.
[0040]
In step 304, the transmission of the air pressure data and the ID from the low frequency transmitter 9 to the air pressure data transmitting device 2 for all the wheels is stopped.
As a result, it is possible to suppress the consumption of the battery built in the pneumatic data transmission device 2 during idling and when the ignition switch is in the OFF state.
In step 305, when the vehicle speed exceeds VB, for example, exceeds 15 km / h, the process returns to step 301 and a transmission start request is sent to the air pressure data transmitting device 2 for all the wheels in the normal air pressure monitoring mode. To do.
[0041]
Thereby, after the normal air pressure monitoring is stopped in the idling state, the air pressure monitoring is resumed when the traveling is resumed.
Further, before the vehicle is stopped and the ignition switch is turned off, the transmission of the air pressure data transmission device 2 for all the wheels is automatically stopped.
[0042]
The air pressure data transmission device 2 of the present embodiment constitutes the first communication device of the present invention, and the control unit 1 constitutes the second communication device.
In particular, the high-frequency transmitter 14 is the first transmitter of the present invention, the low-frequency receiver 15 is the first receiver, the low-frequency transmitter 9 is the second transmitter, and the high-frequency receiver 10 is the second transmitter. Receiving means, the memory 12 constitutes storage means, and the vehicle speed sensor 33 constitutes vehicle speed detection means.
Further, steps 101 to 112, steps 201 to 212, and steps 301 to 305 in the flowchart constitute the control means of the present invention.
[0043]
As described above, according to the present embodiment, both the initial ID registration of the pneumatic data transmission device 2 at the time of shipment of a new vehicle and the case of ID registration or confirmation of the pneumatic data transmission device 2 at the time of tire replacement after purchase of the vehicle are performed. Since each tire pressure data transmission device 2 is requested to transmit IDs individually through the low-frequency transmitter antenna 7 with a built-in door close to the wheel position, and ID registration or confirmation is performed, ID registration is performed for each wheel position. Or confirmation can be made easily.
At this time, since the ID is transmitted for each wheel position according to a predetermined sequence, it can be automatically stored in the memory so that the wheel position corresponds to the ID of the tire air pressure data transmission device 2, and the operator confirms the wheel position. Such a complicated procedure is not necessary.
[0044]
Further, since the control unit 1 can start or stop the transmission of the air pressure data from the air pressure data transmitting device 2 depending on the vehicle speed, it is possible to suppress the consumption of the battery built in the air pressure data transmitting device 2.
[0045]
Further, in the present embodiment, the control unit 1 that controls the air pressure data transmission device 2 uses a vehicle body side device that is used in the smart keyless system, and in particular, transmits a low frequency at a position close to the tire of each wheel. Since the built-in low frequency transmitter antenna 7 is used for each door of the smart keyless system as the machine antenna 7, it can be easily realized only by changing the programming of the microcomputer 11. As a result, an inexpensive tire pressure monitoring system can be realized in terms of cost.
[0046]
The low-frequency transmitter antenna 7 for transmitting a control signal to the pneumatic data transmission device 2 of the present embodiment is built in each door used in the smart keyless system. A separate low-frequency transmitter antenna 7 may be provided at a position close to.
As a result, the intensity of the radio wave transmitted to the air pressure data transmitting device 2 is made as weak as possible, and the ID signal is transmitted only from the air pressure data transmitting device 2 attached to the desired tire, so that the air pressure data of tires at other wheel positions The transmission apparatus 2 can be surely controlled so as not to transmit.
[Brief description of the drawings]
FIG. 1 is a diagram showing a block configuration of a tire pressure monitoring system according to an embodiment of the present invention.
FIG. 2 is a block diagram of a pneumatic data transmission device.
FIG. 3 is a flowchart illustrating a control flow of the tire pressure monitoring system.
FIG. 4 is a flowchart for explaining in detail the flow of ID registration or confirmation.
FIG. 5 is a flowchart for explaining a control flow of transmission start / stop according to the vehicle speed of the air pressure data transmission device;
[Explanation of symbols]
1 Control unit 2a, 2b, 2c, 2d Pneumatic data transmitter 3 Display device 5, 7 Low frequency transmitter antenna 6 Switch 8 High frequency receiver antenna 9 Low frequency transmitter 10 High frequency receiver 11 Microcomputer 12 Memory 14, 32 High frequency transmitter 15, 31 Low frequency receiver 16 Air pressure sensor 17 Microcomputer 21L Left front wheel 21R Right front wheel 22L Left rear wheel 22R Right rear wheel 23L, 23R Front door 24L, 24R Rear door 25 Trunk 30 Card 33 Vehicle speed sensor

Claims (3)

A first communication device that transmits the detected air pressure data is provided for each tire of each wheel, and the second communication device installed on the vehicle body side receives the air pressure data signal to determine whether there is an abnormality in air pressure. In the monitoring device that displays the results,
The first communication device has a first receiving means for receiving a control signal from the second communication device, and is specific to each of the air pressure data signal or the first communication device according to the control signal. First transmitting means for transmitting a signal of the identification code of
The second communication device includes second transmission means for transmitting the control signal to the first communication device through a transmission antenna installed near each wheel, and a signal of air pressure data from the first communication device. And a second receiving means for receiving the identification code signal, a storage means for storing the identification code, and a vehicle speed detecting means, and the second transmitting means and the second receiving means are shared with the keyless system. The transmitting antenna of the second transmitting means is installed at each door of the vehicle,
Furthermore, the second communication device includes a control unit that controls transmission start and transmission stop of the first transmission unit via the second transmission unit,
The tire pressure monitoring system, wherein transmission from the first communication device is stopped when the vehicle speed is less than a predetermined value.   The second communication device transmits a control signal individually from the transmission antenna of the second transmission means, and causes the first communication device of the tire at a wheel position close to the transmission antenna to start transmission, The tire pressure monitoring system according to claim 1, wherein the identification code is received and stored in the storage means in correspondence with a wheel position.   The second communication device compares the received identification code with the identification code stored in the storage unit in correspondence with the wheel position. If the identification code is different from the stored identification code, the second communication device again identifies the identification code. The tire pressure monitoring system according to claim 2, wherein the code is re-received and stored in the storage means in association with the wheel position.

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