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Fault phenomenon: a Cherokee 2.5L, driving in a sudden lack of power, not up to speed, but can drive slowly. Fault detection: after opening a repair shop, a new gasoline pump was replaced, the nozzle was cleaned, but the trouble remained. After listening to the basic briefing and knowing that there was a sudden lack of power, the engine CHECK light on the dashboard suddenly lit up and never went out. This shows that in the process of monitoring the whole electronic control system, the engine has detected the abnormal and stored the corresponding fault code, so the fault lamp will be lit synchronously to remind the attention of the engine. In this way, there may be some inevitable connection between lighting and failure. First of all, the simple switch method is used: the ignition switch is opened and closed three times in 5S, and the number of glittering lights on the dashboard is observed by manual reading and code to see if there is any valuable content. The result shows the fault code 13, meaning that the intake pressure sensor (MAP) signal is not changed, then the MAP three wire plug is pulled, the ignition switch ON, the A-C foot has no normal 5V voltage, but the C foot and the Lite have the normal 5V voltage. Also pull out the throttle position sensor (TPS) plug, measuring A-C feet have normal 5V, MAP C feet and TPS C feet to normal, MAP A feet and TPS A foot can not be guided. Through the map, the C foot of the two sensor is produced by the 5V working voltage of the computer 6 foot; the A foot is the tie foot of the sensor, and the computer 4 foot enters the computer and co sets the iron after it enters the computer. Then the conclusion is only one: the MAP A foot and the computer 4 foot break between the foot, through a section of the probe carefully look up, test, finally found in the MAP A foot line root, although the outer skin is perfect, but the internal copper wire has broken. After the repair, the battery will take off the 15s to remove the fault code, and then the road test, the power is abundant, the fault lights are no longer light, everything is restored to normal, troubleshooting.