What causes a car tachometer to get erratic readings?
Check the fuses to ensure they are properly functioning. Bad wiring can also be the cause of a malfunctioning tachometer. If you are getting erratic readings, this can be a sign of bad wiring. Another potential problem is calibration issues.
When does a car tachometer need to be replaced?
If you are still having issues with the tachometer after troubleshooting various problems, you may just have a bad tachometer. If this is the case, the tachometer needs to be replaced by a professional. The purpose of the tachometer is to read the rotation of the engine’s crankshaft, which is shown in RPM.
What can I do about erratic tachometer needles?
SPA tachometers seem to be particularly sensitive to these spikes, but Auto Meter and Stack tachs seem to be much less affected. The fix is to add a simple 47k Ohm resistor (1/4 watt, 5% to 10%, rated to 500v) in the RPM signal wire from the coil to the tach.
Can a loose kill switch cause erratic tach signals?
If your kill switch is in the negative side of the battery circuit (interrupting the ground), check the switch and its connections carefully. Usually a loose or failing switch will also cause the car to run poorly, but if the problem is very minor it can begin as an erratic tach signal. Fixing the problem now could save you a race later on.
Why is the tachometer on my car not working?
Sometimes, corroded wire connections and breakage may be the reason for the tachometer not working. A classic symptom of a loose wire connection is erratic display of readings.
If your kill switch is in the negative side of the battery circuit (interrupting the ground), check the switch and its connections carefully. Usually a loose or failing switch will also cause the car to run poorly, but if the problem is very minor it can begin as an erratic tach signal. Fixing the problem now could save you a race later on.
SPA tachometers seem to be particularly sensitive to these spikes, but Auto Meter and Stack tachs seem to be much less affected. The fix is to add a simple 47k Ohm resistor (1/4 watt, 5% to 10%, rated to 500v) in the RPM signal wire from the coil to the tach.
What to do if your tachometer goes out of sync?
Check the connection with the battery power source and the engine control unit. Make sure that the tachometer is grounded properly. Fix loose connections if any and replace corroded wires. Make sure that you put the connections back as they were. Another major source of problems in a tachometer is calibration which has gone out of sync.