Failure phenomenon: a 2003 production of the 1998 wide Odyssey, because the speed of the odometer does not go maintenance. According to the owner, the car was previously installed GPS satellite navigation system, for other reasons need to remove the navigation device back to the original car audio. The sound is installed, the odometer is not gone, demolition before everything is normal.
    Fault diagnosis: open the ignition switch, observe the instrument on the lights and the instrument work completely normal. If only disassemble the sound caused by the odometer does not go, most likely the process of disassembly which line forgot to take over or which plug forgot to insert or accidentally knocked off, because this car sound system and odometer Any relationship. So the sound removed. Check the sound near the wiring and plug, no problems found. Had to remove the instrument. See the instrument has a line wrapped with tape. Owners reflect. The instrument on the demolition of this line. GPS has a line connected to it. It took it off. GPS system to be collected speed signal, maybe this line is the speed signal line. In order to verify, find the car circuit. This white / black line is really a speed signal line. As can be seen from the circuit diagram, the car and other common models are different. The speed signal is not a special speed sensor signal provided by the transmission. But by the engine control module according to the transmission speed sensor signal processing output to the instrument, cruise fixed speed system, automatic air conditioning.
    First measure the continuity of the instrument A5 pin and the engine control module A9 feet. normal. Thus. The problem is reduced to the instrument, the engine control module and the sensor on the transmission to the engine control module between the wires. The speed signal is the main reference signal for the automatic transmission shift. When the sensor is faulty, there will be fault code in the engine control module, with HDS diagnostic instrument to detect trouble-free code, read the system data information, hand wheel, the speed shows the corresponding value. And with the rotation speed and the corresponding changes, it seems the engine control module has received the speed signal. Use the DC voltage of the multimeter to measure whether the engine control module A9 pin has no speed signal output. The multimeter shows 1.2V. There is no change when turning the wheel. Under normal circumstances, when the wheel by hand should be 0 ~ 5V constantly changing, the fault out of the engine control module without speed signal output, rather than instrumentation problems. The engine control module price is more expensive than the instrument; the engine control module to see if the maintenance can see. Along the A5 foot measurement and found that the engine control module has a transistor breakdown, but the appearance of no trace of burned. Replace the same type of transistor. Test, troubleshooting.
    Fault Summary: Analyze the maintenance process. The engine control module burned the main reason may be broken when the cable is not removed, instantaneous induction voltage is too high breakdown transistor. This requires us to repair part of the electronic control, in strict accordance with the maintenance manual in the relevant requirements, can not hold the chances, so as to avoid unnecessary losses.