Re: 54 Packard ignition switch / cylinder head temp gauge
Posted by HH56 On 2023/4/14 20:56:19
It is doubtful you will be able to use a 12v electronic gauge directly powered from a 6v positive ground supply. I doubt your new gauge uses the old bimetal or even magnetic operation like the original gauges Packard used so the issue is not only voltage but also the solid state components inside the gauge. Solid state is polarity specific and I suspect the gauge will not have the added components needed to make it universal. Most gauges today also use LED illumination and if that gauge does, typical implementations of the LED will be another polarity specific item. The LED will probably have a current limiting resistor calculated for 12v and will be dim if it lights at all on 6v. Since there is only one wire to power the LED and only one coming from the sender, the gauge will most likely be needing a negative ground. You might check the paperwork carefully to see if there are specific requirements.
There are some 6 to 12v converters which can work with mixed grounds and convert a 6v input from a positive ground car to power a 12v negative ground electronic item. I suspect you will need something like that to power the gauge and will also need to power the LED from it rather than the illumination power coming from the dash light circuit. The other option which would give you a lot more flexibility would be to get a purely mechanical gauge.
Another question would be where you are going to place the sensor. If you are going to keep the original gauge and sender then there are limitations on where you will be able to get a reliable flowing water temperature unless you are not measuring water temp but strictly the surface metal head temp and plan to somehow mount the sender on the head surface.
Here is the back of a 54 ignition switch showing the terminal designations. IGN is the terminal closest to the lamp and bracket. It will be hot only when the key is turned to the right or run position. ACC will be hot in either key direction.
Attach file:
IMG_2613.jpeg (48.86 KB)
There are some 6 to 12v converters which can work with mixed grounds and convert a 6v input from a positive ground car to power a 12v negative ground electronic item. I suspect you will need something like that to power the gauge and will also need to power the LED from it rather than the illumination power coming from the dash light circuit. The other option which would give you a lot more flexibility would be to get a purely mechanical gauge.
Another question would be where you are going to place the sensor. If you are going to keep the original gauge and sender then there are limitations on where you will be able to get a reliable flowing water temperature unless you are not measuring water temp but strictly the surface metal head temp and plan to somehow mount the sender on the head surface.
Here is the back of a 54 ignition switch showing the terminal designations. IGN is the terminal closest to the lamp and bracket. It will be hot only when the key is turned to the right or run position. ACC will be hot in either key direction.
Attach file:
IMG_2613.jpeg (48.86 KB)This Post was from: https://packardinfo.com/xoops/html/modules/newbb/viewtopic.php?post_id=255859