I changed a throttle assembly. Do you have this trouble? The car was still on as before, and then turned off.

Your question is too general. You should provide the fault code for analysis. The fault phenomenon is that when you stop, you slow down in neutral or idle speed, then turn off the engine, and it is normal to restart after turning off the engine.

That is to say, when a fault occurs, the computer detects a fault and lights it up. At the same time, there is also a problem with idle speed control because of the fault. Judging from the information you provided, the fault code should be on the idle motor control and its circuit, and the maintenance personnel will clean and replace it. Then it can basically be judged that there is something wrong with one of the three points: computer, idle motor and circuit. After turning off the ignition switch, the computer can run again without finding any problems. At first, the maintenance technician cleaned the idling motor, because it was artificially generated. Later, the key suspect idle motor was replaced. Later, the vehicle was in use, and the fault was not eliminated, and then it was suspected to be a computer. However, there was no problem after the computer was shut down and restarted, so the computer was upgraded, but the situation did not improve. Therefore, it is certain that it is not a computer program problem, but a control problem, and control requires a circuit. Whether there is a short circuit fault in the circuit, and it is intermittent fault, needs to be confirmed. Based on the above ideas, this needs to be confirmed. Connect four wires directly from the computer terminal to the idle motor, disconnect the original wire connector, and control the idle motor with a new wire. If the fault does not appear, then the problem lies in the wire. If the problem still exists, analyze the cause of the fault through traffic data flow, such as how many steps does the computer control the idle motor? If it goes directly to 100, then the computer controls the idle motor not to turn. If the computer doesn't control it at all, check whether the output of the throttle position sensor is on the idle contact or whether the idle output voltage is between 0.5 and 0.8V, so as to ensure that there is no problem with the data provided to the computer. Then, if the line is short-circuited, the computer may be replaced.