# Jeep YJ to CJ Dash Conversion - Gauge Help

Hi,

First off, I’m very new!

I’m in the process of converting my Jeep YJ dashboard to that of a CJ (old school), and I think the Arduino can be used to get the stock CJ gauges working correctly. Mostly, I’m looking for someone to point me in the right direction!

Conversions have been done before, but only the speedo was used - stock gauges were replaced due to sending unit OHM differences.

What I’m looking to do is bridge the gap between my YJ sending units and the CJ gauges without gauge or sending unit replacement.
For example:

My YJ Oil Pressure Sending Unit-
0 psi = 10 ohms;
40 psi = 45 ohms;
80 psi = 90 ohms

My CJ Oil Pressure Gauge-
0 psi = 234-246 ohms;
20 psi =149-157 ohms;
40 psi =100.5-105.5 ohms;
60 psi =65-69 ohms;
80 psi =32.5-34.5 ohms;

They are separate linear readings, so it should be possible to vary input to output resistance by percents?

frank:

How did you obtain these 'ohm' values?

Your dashboard gauges are most likely 'ammeters' (actually voltmeters connected across a known resistance) and therefore it is a current or voltage value that is what you should be dealing with.

Both of my CJ5s had idiot lights for the oil pressure. I guess you are dealing with CJ3 gauges.

Don