as the title say the tach on my 93 240 kade is very jumpy when crusing it tweaks allot. ie on the highway doing 100km it stays @ 2500rpm and is steady but then twitches to 3000 to 4000rpm. like when u wigle ur finger lol
basically just wanna know how the tach gets it’s reading and what cause said problem
Either your speed sensor is fucked, or you’ve got bad grounds causing it to fuck up.
When it starts getting all jumpy, trying tapping the top of the dash to see if that temporarily stops it from happenind.
But i’ve got my finger on the sensor actually malfunctioning, since it only gets figity when travelling at high speeds, no?
lol starting to get worse 
now when accelerating it jumps to but lets i’m accelerating stready and the engines is @ 2000rpm and climbing it will twich to around 5000 to 4000 and back down then then repreat perty rapidly
time pour new clustar garcon.
^^^^ i was hoping it wouldn’t come to that
car runs fine i’m assuming. if it is intermitent. i say cluster for sure. well, the tach part anyway
^^ Ditto
I forgot to mention that aswell.
Swap in a new one and see if you still have the same problems.
instead of replacing the cluster, maybe there’s a way to finding out what electrical short or fuse or something can be fixed or repaired.
^^^ exactly!!! just need to know how it works and where and what it uses to get the signal
Try looking on google?
Im not entierly sure, but i’ve read/heard somewhere that the sensor is located near the tranny? lol
If you do find it, maybe its just dirty and thats causing it to short out.
Other then that, when it starts getting fucked, just BANG the top of the cluster, and that should work haha. I had a buddy that had the exact same issue, but was to lazy/frustrated to actually fix it.
gl.
Check to make sure speed sensor wire isn’t near any other wires. There’s enough rotating metal stuff (gears in your tranny, etc) near it that it could introduce a magnetic field. It could possible induce a current in the wire and start giving you false readings