Tachomete reading 50% of actual engine speed

[JerryHonolulu]

1991 LS400, 150K miles. Tachometer is reading approximately 50% of actual engine speed. What's the likely problem?

[CELSI0R]

I had the same problem on my 1991. It is more than likely that the needle is loose and needs to be reconnected to the motor unit it is a part of.

The repair a delicate procedure, but it is doable. Take a look at my post here, where I explain a fix for this condition. This is specifically where the needle sits below the 0 marker when the engine is off.

If your needle does not sit below zero when the cluster is on or off (with the engine off), this solution may or may not work. If you attempt this procedure, take your time and make sure to keep the gauge cluster surface clean of oils, etc.