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dodge ram speedometer problems
First, check the high-pressure fire. It is found that there is no high-pressure spark when starting the engine. Then check the fuel injection of the fuel injector with the LED light, and find that there is no fuel injection signal when starting the engine. Unplug the connector at the wire side of the fuel injector and check the power supply of the fuel injector. The power supply of the fuel injector is normal when the ignition switch is turned on. Continue to check and find that the power supply of the ignition coil is also normal. Check the harness on the automatic transmission. All connectors are firmly inserted.
Connect the fault detector and enter the engine electronic control unit to read the fault code. The fault is that the crankshaft position sensor signal is weak. Check the engine speed data in the data stream. When starting, the engine speed is 0r/min, indicating that the engine electronic control unit has not received the crankshaft position sensor signal. The crankshaft position sensor is a three wire Hall sensor. Unplug the connector at the wire side of the sensor, and the measured working voltage of the sensor is 7.5V. Check the grounding wire and it is normal; Use LED test lamp to measure the sensor signal, and the test lamp does not flash; After readjusting the clearance between the crankshaft position sensor head and the signal wheel, the test still has no effect. Replace the crankshaft position sensor and adjust the installation clearance before starting the engine. After binding along the original vehicle harness, a road test was carried out, and a new fault was found: the automatic transmission does not shift, and the maximum speed can only reach 80km/ha. After returning to the factory, call the automatic transmission supplier, and the other party guarantees that the automatic transmission is good, which has been strictly tested and verified before leaving the factory. Before the automatic transmission is changed, although the automatic transmission of this vehicle will slip, it can shift. Therefore, the automatic transmission control unit should have no problem.
(1) Drive on the road to make the vehicle speed from 0 to 72km/h, and manually shift from first gear → second gear to third gear → fourth gear. Repeat the operation for 15~20 times;
(2) Keep the vehicle speed below 40km/h, and press the accelerator pedal to the bottom to force the automatic transmission to downshift from gear 3 to gear 2, and then from gear 2 to gear 1;
(3) Keep the vehicle speed above 40km/h, and press the accelerator pedal to the bottom to force the automatic transmission to downshift from gear 4 to gear 3, then from gear 3 to gear 2, and finally from gear 2 to gear. After completing the automatic transmission control unit self-learning program according to the above method, the vehicle is tested again, and the automatic transmission shifts normally. A week later, after a follow-up call, the car has been driving normally, and the fault has been completely eliminated.
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