Hey Daniel,maybe you can tell me whats going on! ThanksCan someone please tell me what the HELL IS GOING ON? I have a 96 no engine mods yet. I having a problem with my RPM meter, The meter will start to go crazy it will drop to zero while driving and start moving back and fort fast but the car drives fine. I check the spark plugs took the meter out but every thing seems fine. I do not want to take it to the dealer yet because the dealers in my area are all thieves. Please Help! Anyone knows what else I can check.

 

The two Crankshaft Position Sensors send signals to the Engine Control Module. The ECM uses these signals for a variety of purposes including driving the tachometer. Since your engine runs well even when the tach misbehaves, it is likely that the sensors are good. Therefore the defect lies somewhere between the ECM and the tachometer instrument itself.

You may backprobe connector M82 at the combination meter. M82 is a white plastic connector with 14 positions. Viewed from the harness side, identify terminal #3 which is in the upper row, third from the left. The wire at terminal #3 is white with a green stripe. Measure the voltage between terminal #3 and ground while the engine is running. The factory service manual says the voltage should vary in direct proportion with engine RPMs, but does not provide any specific values. If the voltage you measure at this point fluctuates wildly, that indicates the defect lies "upstream", probably in the wiring between M82 and the ECM. If the voltage is steady but the tach reading is erratic, the defect lies "downstream", in the combination meter assembly and possibly the tachometer instrument itself. The delicate Flexible Printed Circuit connection in the combination meter is a potential trouble spot. Cracks and cold solder joints in the Combination Meter printed circuit board could also produce this symptom.

It will take time and patience to track down this problem. If you have a background in electronics you may want to do this work yourself. Any shop, dealer or independent, will have to bill you for diagnostic time. With this kind of problem it is impossible to predict the labor bill. You might find the problem in the first five minutes, or it might take six hours. Luck is a factor in this situation.

Please don't brand all Nissan dealers as "thieves". Some of the finest technicians in the business work at dealerships.

 

I did not brand all Nissan Dealers as thieves, What I said was the ones in MY area. Thanks for the help.