A 2005 Accord CM5 sedan, due to automatic transmission shift lever lock, can not enter the block driving, maintenance personnel using temporary emergency measures to shift lever emergency button press, forced into the D block, the vehicle slowly back to the maintenance workshop The After the vehicle into the workshop, the shift lever back to the P block, and then can not move into any other position, locked in the P bit.
    First connected to the HDS Honda diagnostic apparatus for detection, did not find the fault code. Observe the engine data stream, TP value of 10%, the relative TP value of 9%, ignition timing is 26 °, the engine speed 1200r / min, from the data flow point of view, the most obvious is the engine is not idle operation, ignition The advance angle is locked at 26 ° and the relative TP value should be 0% at idle conditions and is indicated as an error value of 9%. At this point the engine management system has started the backup mode, no longer carry out the relevant parameters of the sensor correction. Fuel discharge control system was open-loop state, while starting the engine and automatic transmission protection mode circuit, the shift lever locked in the P bit, the car fault phenomenon. To remove the shift lever lock, you must find the root cause of the fault! I have encountered due to wading caused TP damage to the sensor, causing the shift lever to lock the fault, for the throttle body assembly (Honda CM5 TP sensor can not be removed), the fault can be ruled out. This fault from the data flow point TP value is basically normal, but the relative TP value is high, will be due to occasional failure caused by throttle position sensor learning value changes? I use HDS ECM / PCM learning value to re-set, troubleshooting. Shift lever to unlock the state, the car finished factory.
    But this car only driving a day later, the user will drive into the factory, repair the same failure. HDS detection, data flow or the same content. ECM / PCM learning values ​​are reset with HDS, but can not be completed. Replace the confirmation of a good throttle body assembly (TP sensor can not be replaced separately), from the data flow point of view, TP relative value or show 9% unchanged, once again with HDS ECM / PCM learning value reset, or can not complete The Shift lever is still locked, the fault remains the same. This time HDS can not be throttle position sensor learning value set, really confused. Finally, we take the battery removed to remove the battery, waiting for tens of seconds, in this way to remove the ECM / PCM random memory learning program. Connected to the negative line, put on the original car throttle body. Start the engine, in the idling conditions observed data stream TP relative value of 0%, TP value is normal, ignition advance angle in 6 ~ 15 ° change, shift lever unlock. Road test 30km, did not find the fault to reproduce.
  I once again on the car road test and found that when the air conditioning compressor work, the engine idling conditions have become quite bad, the engine jitter, idling speed down to 400r / min, serious when the engine has to turn off the state. From this point of view, in the air conditioning compressor work, the engine idle power compensation is not enough, resulting in engine output power is small, causing the engine idling jitter. One of the main components of the idle power compensation is the Idle Control Valve (IAC) and the associated control circuit, which first cleans its mechanical valve body. After removing the valve body, it was found that the spool was filled with coke (with photos). After cleaning the installation of the engine, open the air conditioning when the idle power compensation is good, idle running smoothly. Idle shaking troubleshooting, through this point that IAC valve control line is not faulty. Then road test more than 100 km, did not find the shift lever lock phenomenon.
    Damage to the valve body
    Maintenance here, we will ask, an IAC valve shift lever to lock what is the relationship? May not understand and accept, the author below to briefly analyze their causal relationship, it is not difficult to understand. As the IAC valve body is full of coke, resulting in slide valve running stuck. Because its stuck position is random, when it stuck in the opening degree, the idle air compensation air into the more, then the IAC valve instruction is not the current slide valve opening instructions required, too much Idle air compensation, resulting in engine speed from idle speed 750r / min rose to 1200r / min. The fuel injection time is not the current required fuel injection time, when the throttle position is in the closed position, the engine water temperature is also at normal temperature, these correct sensor parameters and slip valve due to the resulting incorrect Of the sensor parameters, and then ECM / PCM memory (ROM) curing reference data to compare, ECM / PCM through the calculation of a conclusion that the engine is not running under idling conditions, but the actual situation is indeed in idling mode , But the engine speed in the idle conditions exceptionally increased.
    ECM / PCM will compare the parameters of the conclusions (error parameter data) to learn. The result of the study resulted in a relative value of TP of 9%. In other words, ECM / PCM that the throttle position at this time in the correct closing position of the opening (10%) on the basis of the default opening 9% of the opening position, but does not meet the idling conditions of 10% Of the opening, so the memory relative to 9% of the opening value, which starts the engine and automatic transmission protection mode, the shift lever to lock. We now come back to analyze, since the slide valve stuck is random, then it is another state is when it stuck in the opening of a small position, that is, air compensation is not enough, IAC valve command signal is right, but slippery The valve does not open to the designated location, less air compensation. At the same time, the fuel injection time of the injector is also adjusted accordingly, but the adjusted injection time is not proportional to the air provided by the slack valve, resulting in a dislocation of the combustible mixture at idle conditions, So that the combustion of the cylinder is not complete, in the idle conditions, the engine output power is insufficient, causing the idle conditions open air conditioning when the engine shaking the serial failure. From the above analysis, this is a fault from the IAC valve stuck to start the process of careful diagnosis, and ultimately ruled out the shift lever lock fault.