Tacho Problem

[defari]

r33 series 2 gtst

i know its a common problem with skylines... dancing tacho etc.. However, the difference with mine is sometimes it will go crazy for a bit.. sometimes it will read the correct rpm (ive also got an apexi rsm)... but then sometimes it will read exactly 1000rpm more than the RSM... and when im on/off the throttle the rpm needle will increase and decrease as it normally would when accelerating/decelerating.. (also to note, this is without touching the cluster as some people have said by pushing it in it will read the correct rpm briefly)

Any ideas?

[SargeRX8]

I don't know what an rsm is but you said the tacho shows a different, the wrong, reading compared to the rsm. This tells you the fault is directly with the tacho. Both of these components read directly from the ecu or the sensor on the box. Both displaying different outputs. If both displayed the same output but the output is wrong then the sensor is at fault. Sounds to me like intermittent failure which will one day fail completely inside the tacho... Maybe you can get lucky, clean the connectors at the back of the tacho, plug it in tight and see what happens. Check dry solder joints. Might be a capacitor or resistor failing.

[defari]

rsm is this

yep im pretty sure its just the tacho failing but im just curious as to why the tacho smoothes itself out but just reads 1000rpm more than the rsm... hard to explain but when i throttle on and off the rpm will increase/decrease normally but just 1000rpm more than the rsm..

from what i read if its failing - it should be dancing constantly right? rather than getting a steady rpm signal but just 1000rpm more than the rsm

Edited February 29, 2012 by defari

[SargeRX8]

Hence why I think there is a resistor in there or a capacitor in there which could be failing. I have no idea about the electronics in the tacho bit in general electronics if you use a resistor in a circuit to add resistance and lower a voltage/signal, but have it wired in a way that if the resistor fails the circuit still works then this could explain your problem of a consistent 1k+rpm reading...

[defari]

ahhhh sweet... that makes sense!

Cheers Sarge

[SargeRX8]

Open it up, carefully and gently, and look for things which just don't look right. Bad solder joints, cooked resistors, damaged tracks, anything physically wrong. Smell it too, see if it smells like burnt electronics.

[defari]

will do - cheers for the info mate - ill grab a pic while im at it - electronics are not my forte - someone might be able to spot something that ive missed.

[defari]

Some how its just fixed itself. Dont know how. Didnt touch anything..

[SargeRX8]

Bad solder joints or loose cable

Edited March 4, 2012 by SargeRX8

[defari]

yeah looks like it - havent taken it out yet seeing as it fixed itself for a few days.. i hit a decent bump in the road this evening... tacho went beserk again.. will take it out tomorrow for a look