Electrical gauges and sending units

[black_demon69]

Question is can the factory gauge and a aftermarket temperature and oil pressure gauge share the same sending unit with the factory gauges and retain the function of the factory gauges?

 

[JOLENE_THE_RANGER]

as long as you can find a sender that uses the same ohm range as the factory one then yes.

 

[Bird76Mojo]

If you have trouble finding one that shares the same ohm values, then if there's room you might use a brass T-fitting to run two sending units. Looks a little odd but it would get the job done.

 

[Curious Hound]

The older trucks just have a pressure switch for oil pressure. So if you want an actual pressure reading you will need a pressure sender. I read somewhere that there is a way to modify the gauge cluster so it will read pressure once you install a sender. Check the tech articles.

 

[Dirtman]

Yup, your gauge isnt a gauge and your sender is a switch. Ford used the pressure switch they use with warning lights (on or off) to run a gauge. So the needle on the guage doesn't actually do anything, it just moves to the halfway mark when the pressure switch is on.

Dumbest thing on earth but I guess ford figured a fake guage looked cooler than a warning light.

 

[JOLENE_THE_RANGER]

does it do the same for water temp?

 

[Curious Hound]

No. Water temp is for real

 

[RonD]

For temp you can isolate the two gauges to share one sender by using a diode on the added gauge's wire to sender
But yes the added temp gauge would have to be calibrated for the sender being used

Oil pressure on Fords after 1986 or so was an on/off sender, so you would need to add a PS60 sender to use with a pressure gauge
Than can be done with a "T" fitting so both senders can share the oil pressure port, and add another wire for the PS60 sender

 

[Bird76Mojo]

If Fords after 1986 used an oil pressure switch, then why does my oil pressure gauge in my 87 Ranger change based on the oil temperature and run time?

 

[RonD]

It may still have a PS60 sender and open gauge(no resistor)

But the on/off switch gauge should also change, but from system voltage
When you start cold engine, the alternator will be outputting 14.5-14.9volts to recharge battery, so oil gauge shows higher
As battery gets recharged(and oil warms up) the alternator lowers voltage down to 13.5volts, so pressure gauge goes down a bit
As you REV the engine, voltage can rise with RPMs until voltage regulator stops the rise, oil pressure goes UP with RPMs


Look for your sender
PS60 sender looks like this, gold or silver color: https://www.ebay.com/itm/PS60-Oil-P...ncoln-Mercury-Ford-Jeep-AMC-NEW-/261806685748

Switch type sender is much smaller, like this: https://www.ebay.com/p/Engine-Oil-Pressure-Sender-Sensor-for-Ford-Lincoln-MAZDA-Mercury/18022235839

Up to about 1995 Rangers you can pull the cluster and jumper the resistor on the back of the oil gauge then install PS60 sender to change to "real" gauge
Around 1995 Ford switched gauge to internal resistor so hard to by pass it, same year they switched to electric speedometer

 

[black_demon69]

https://www.rockauto.com/info/154/PS240_FULL__ra_p.jpg

This is what my current oil sender looks like

 

[Curious Hound]

Looks like the switch in my opinion. I think RonD nailed it.

 

[Bird76Mojo]

I'm running the larger pressure sender on my 302. Maybe I should look in to jumper'ing the resistor on the cluster. Although I know my 87 oil pressure gauge isn't changing due to battery voltage or rpm already.. It's definitely oil temperature related. I can shut the truck off and restart multiple times and the gauge will return to where it was before. I let it cool for an hour or two and the pressure will be higher on the gauge.

 

[RonD]

The resistor, if its there, would just give you a higher reading from the PS60, at or above 1/2 way

With a switch is sits at 1/4-1/3 usually, when switch is closed

 

[black_demon69]

Thanx for all the information and tech article was very helpful