WadeLovell

iTrader: (5)

Emboldened by posts on the topic of 1990+ Toyotas having an on board potentiometer, I tore apart my Lextech cluster intending to set things right in my 1993 SC300 only to find Tachometer part number 256995-018 appears to lack a potentiometer. Intrepid me, I then tore into a trash cluster from an SC300, p/n 83010-24530. However, it has the exact same Tachometer p/n. I am going to swap them anyway but, before I reinstall the SC400 cluster into my SC300 with the Tach from the old SC300 cluster, can someone please share with me whether this is going to change my high RPM reading and, if not, where I would wire in a potentiometer?

99SC42

iTrader: (44)

Your tach will be 1000 rpm OFF

WadeLovell

iTrader: (5)

Shouldn't it be xxx% of actual across the entire range since it is receiving more signals than it would were it properly calibrated? I.e., if it is receiving 6 pulses for every 4 it would receive in the SC400, then it would display 150% of the actual RPM.

However, that is unrelated to the question I asked.

WadeLovell

iTrader: (5)

What I found once I removed both tachometers from their clusters is the ICs are different part numbers. The SC300 IC part number has an L and the SC400 IC part number has a P. I will post the actual IC part numbers when I get back to the garage. I believe one can replace the IC in an SC300 or SC400 cluster to achieve the proper calibration when swapping clusters between these vehicles.

WadeLovell

iTrader: (5)

SC300 IC1 p/n is 11L25
SC400 IC1 p/n is 11P24

Unfortunately, the person before me who was messing around with the SC300 cluster clipped the 50v 2.2 microfarad capacitor off which should be connected at C5.

I am debating my next move. Suggestions?