When i first reinstalled the dash i had to pull the headlights on and off or touch an extra ground wire to the tach body to get the tach to read. Gary gnichols may 12 2017.

About Our Tachometers
Tachometer reading too low. Connect a diode 1n4005 between the negative terminal or 1 of the coil and the wire that goes to the tachometer. Checked the rpm with my analyzer tach and it was reading 6000 when the limiter kicked in. This problem can be taken care of by resetting the digital tachometer. Two things to note. The cathode end silver band should be nearest the tachometer side not the coil sideyou should be able to buy a diode 1n4005 at radio shack or other electronic supply store. It just reads real low and responds slow almost as if there were a resistor in the signal wire.
Rpms tachometer reading low at times home forums stay dirty lounge service and repair questions answered here rpms tachometer reading low at times this topic contains 8 replies has 4 voices and was last updated by ericthecarguy 7 years 8 months ago. If the tachometer is still faulty replace the tachometer. Could a weak ground cause a low tach reading. I noticed that the rpm limiter was kicking in had a 6000 rpm pill in the 6420 box but the autometer tach was reading about 4000 rpm. Fuel gauge not reading either although when tested with a 9v battery it does function. Another major source of problems in a tachometer is calibration which has gone out of sync.
One i have an msd 6btm with tach driver in order to have boost retard on my scd 91 5sfe. You may notice that rpm readings are really low or unusually high compared to engines working status. Low tachometer reading my tach is reading low by about 2000 rpm at upper end and 200 low at idle. It is not like it is disconnected as it is not completely dead. I have one that reads double what it should on a non hamb car. Works on start up now just reads low.
If so connect the gray wire you removed previously to that yellowgray terminal. Technical tach reading low. About two weeks ago my tachometer started acting funny and read about 500 800 rmps. Dec 3 2009. That is a clear indicator of problems with calibration. Perhaps your thread will help me too.
Discussion in the hokey ass message board started by. Videos you watch may be added to the tvs watch history and influence tv recommendations. If playback doesnt begin shortly try restarting your device. Start the engine and check the tachometers operation and if the tachometer operates as it should then the regulatorrectifier is faulty and will require replacing.