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d4 light blinking and speedometer not working
1. Idling warm up the car is not the longer the better. When the car is heated for a long time, the engine does useless work, wastes fuel and is not conducive to environmental protection. Generally speaking, due to the low temperature in winter, the viscosity of the oil at the bottom of the engine is relatively high, and the warm-up time takes a little longer, usually 3-5 minutes. A simple judgment is to see that the pointer of the tachometer turns to within 1000 rpm, and the water temperature gauge starts to move and you can drive normally.
2. Never step on the accelerator when idling. It is best to drive steadily at a speed of about 40 yards per hour in the first 2-4 kilometers of driving. Otherwise, the engine will wear out rapidly and the engine parts will be seriously damaged.
3. Small-displacement hot cars must be thorough, such as 3-cylinder or 4-cylinder displacement. Because the small displacement means small power and large load, the machine can't stand it when the car runs cold all of a sudden. Conversely, a car with a large or slightly larger displacement can basically go when it is warm.
4. The underground parking lot is hot, and you must not leave with a little water temperature. Because when you come out of the underground garage, you basically have to go up a steeper slope. At this time, the engine has not yet reached the normal working temperature. If you bite the bullet, you can only make the car wear more.
Maintenance: if the engine fault light and D4 gear indicator light are abnormally lit, it means that the engine and automatic transmission system are faulty. Use the diagnostic instrument to self diagnose the engine system. The result shows that there are 3 fault codes, including no pulse signal of camshaft position (CMP) sensor a, camshaft position sensor signal deviation and automatic transmission system fault. Conduct self diagnosis for the automatic transmission system, and there is no fault code. Clear the fault code of the engine system, start the vehicle, and the engine fault light and D4 gear indicator light will go out normally. Step on the accelerator pedal to accelerate. When the engine speed rises, the engine fault light comes on again, but the D4 gear indicator light does not come on. Re read the fault information, only p0344 remains, which indicates that camshaft position sensor a is intermittently interrupted.
Camshaft position sensor
The engine has two camshaft position sensors, camshaft position sensor a and camshaft position sensor B, which are installed at the rear of the cylinder head. Unplug the 3-pin harness plug of camshaft position sensor a, turn on the ignition switch, and measure that the voltage between terminals 3 and 2 is 12V, which indicates that the power line and ground wire are normal. Plug in the 3-pin harness plug, connect the probe of the oscilloscope to terminal 1, start the engine and measure the signal waveform. If the result is a straight line, it means that there is no pulse signal output. Remove camshaft position sensor a and check that the signal in the mounting hole triggers the impeller, which is normal. Camshaft position sensor a and camshaft position sensor B are basically the same in terms of structure and working principle. A comparative test is conducted to measure the signal waveform of camshaft position sensor B, with pulse rectangular square wave output. This indicates that the camshaft position sensor a is damaged or the circuit is poorly connected. Find the power system control module under the center console and check the wiring between the harness plug and camshaft position sensor a. the connection is good. At this point, it can be judged that the camshaft position sensor a is damaged. Replace and completely eliminate the fault.
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