The vehicle mentioned in the title has 300,000 KM. Recently noticed the tachometer rises smoothly with pressure on the accelerator, but seems to over-register the engine rpm. The vehicle behave normally in all other respects and the transmission fluid is bright pink. Could the pickup or ECM, or TCM be at fault and where and what is the sensor that generates the tach dashboard display.
Thanks
I believe that most tachometers from that era run off of the signal on the points or whatever the timing pickup is on your car. So unless the points are bouncing _really really bad_, or the timing pickup is somehow misbehaving, then it's hard to see what may be wrong with the signal.
What leads you to believe that the engine isn't over-speeding?
There's a chance that something has gone haywire in the tachometer itself. Is there anything that makes you think it's outside of the tach, or are you just trying to figure out the system to isolate the problem?
Put a scan tool on it and see what it says for RPMs. Could be that the stepper motor in the tach is failing.
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