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nissan maxima speedometer not working
First of all, analyze the working principle of the speedometer of the nissan maxima car. The ABS wheel speed sensor of the vehicle sends a wheel speed signal to the ABS control unit, and provides a vehicle speed signal to the integrated instrument and A/C amplifier through the CAN communication line. After receiving the vehicle speed signal, the integrated instrument and the knife C amplifier will convert the signal into an 8-pulse signal and provide the 8-pulse signal to the vehicle speed odometer in the instrument. Test run, found that the fault phenomenon really exists. Then perform the instrument self-diagnosis according to the following steps.
(1) Turn the ignition switch to ON and switch the speedometer switch to "Trip A" or "Trip B".
(2) Turn the ignition switch to OFF.
(3) While pressing the speedometer switch, turn the ignition switch to ON again.
(4) Confirm that "0000.0" is displayed on the speedometer.
(5) Press the speedometer switch at least 3 times within 7s after the ignition switch is turned on.
(6) All fields of the speedometer and the A/T indicator will illuminate, and the low fuel warning lamp indicator will also illuminate. At this time, the integrated instrument control unit will switch to the diagnostic mode.
(7) Press the speedometer switch, then all instruments will display, the engine tachometer pointer is at about 2500R/min, the speedometer pointer is at about 55km/h, the fuel gauge pointer is at nearly half of the position, and the low fuel warning lamp is off, the low coolant warning lamp and the high coolant temperature warning lamp are on.
After the self-diagnosis of the integrated instrument, confirm that the vehicle's speedometer is in good condition and free of fault. Connect the fault detector to enter the ABS and integrated instrument system, and there is no fault code stored; Connect the fault detector and carry out a road test on the vehicle. From the data flow, it is found that the signal values of each wheel speed sensor are normal. The ABS wheel speed sensor, ABS control unit and other related circuits and connectors are also normal.Remove the CD player, take out the integrated instrument and A/C amplifier, start the engine, and drive the vehicle at a speed of about 40km/h. Use a multimeter to check the voltage between the terminal 26 of connector M42 on the wire side of the integrated instrument and A/C amplifier and the grounding, which is 0V, abnormal. Check whether the harness connector and harness of integrated instrument and A/C amplifier are normal.Check the continuity of CAN communication line from ABS control unit to integrated instrument and A/C amplifier. Unplug the wire side connector of the ABS control unit, measure the continuity of the wire between the wire side connector terminal 1 and terminal 1 of the integrated instrument and A/C amplifier and the wire side connector terminal 1 and terminal 2 of the ABS control unit, which are also normal. According to the working principle of the speedometer, since the integrated instrument and A/C amplifier have no pulse signal output and the vehicle speed signal is normal, the CAN communication line between the ABS control unit and the ABS control unit to the integrated instrument and A/C amplifier is normal, which means that the vehicle speed signal to the integrated instrument and A/C amplifier is normal, but the amplifier does not output the 8-pulse vehicle speed signal, It can be judged that the integrated instrument and A/C amplifier are damaged.
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