oil pressure sending unit

[burdar]

I replaced the AMP gauge with an oil pressure gauge since the car only came with an idiot light.  I want to retain the idiot light because I think a bright red light on the dash will immediately tell me there is a problem.  I could run a T fitting off the back of the block and install both sending units but that will look busy and could have the potential for more leaks.  There is a factory sending unit #53030493 that was used on the 92-96 5.2L that combines both sending units into one.  It has two pins on it...one feeds the gauge and the other is for the light.  I'd like to use this unit but I wonder if it will work with my 2" SunPro gauge I just installed.  The gauge came with the large can sender...the same size as the factory one.  Is there a way to find out if the gauge will read correctly with the late model sender?

I could hook up a mechanical gauge just for testing to see if they read the same BUT, that would require buying the sending unit first.  Maybe that's the only way to be sure...unless others have done the exact same thing.

[Chryco Psycho]

Never tried it , let us know .
 On my race car I had a 10 PSI switch that opened below 10 psi killing power to the ECU 

[Bullitt-]

found this....  "Any way I put a little air pressure on it and measured about 60 ohms at 20psi and about 40ohms at 40 psi on the right pin"

http://www.cumminsforum.com/forum/89-93-non-powertrain/501621-91-oil-pressure-sensor-failure.html

Try that on your new sending unit. 

[ShelbyDogg]

I just use the brass t fittings from the auto parts stores.  It is machined with a threaded pipe thread on the bottom with a female on top and one on the side. I can use both the rallye and idiot light sender without any problems. The dual unit sounds like a piece that will fail.

[jordan]

I just changed out my oil sending unit tonight.  I had my gauges rebuilt at Redline.  I removed the clock and added an oil pressure gauge.  Initially, I just hooked up the factory connector to the factory sending unit.  I talked to Shannon at Redline and he said I needed a dual sending unit.  The factory wire connection will do the idiot light, and I had to run a second wire from the sending unit to a spade connection on the back of the gauge.  The sending unit doesn't use spade terminals, as it uses a threaded post with screw fasteners.  It doesn't look stock, but it is supposed to work.  It was a bummer trying to tighten it into the block since there is limited room and it has a larger hex than the stock one, but it fit eventually.  Try Redline for the sending unit.  A couple of new connections and it should work.  Good luck. 

[burdar]

I haven't gotten back to looking at this further.  My dealer contact is out for 12 weeks after back surgery.  Eventually, he is going to look and see if there are any ohm references in the factory service manuals.  I really don't want to run a T.  It will look much cleaner with a single sending unit running both the light and the gauge.

"Jordan", are you saying you replaced the idiot light sender with a dual sender?  It must be different then the one I found.  The one I found uses a newer style single plastic connector.  Can you take a picture of the one you have?  No hurry...I'm working on other things right now.

[jordan]

Give me a few days and I can get a photo up.  Hopefully by the weekend.  I just checked redlines website for a chance of a photo with no luck.  Ill show you mine.  J

[Jamiez]

Can you take a picture of what you have?  It should be pretty easy to design a simple circuit to make a certain reading on the oil pressure gauge trip the idiot light. Probably less than $30 in parts.

[burdar]

I don't have anything at the moment.  I just read a link on "allpar" that showed the switch used in 90's trucks.  It did away with the leak prone "T" setups the factory was using.

Around the middle of the page. Notes 3-5...
http://www.allpar.com/history/mopar/electrical2.html

[ShelbyDogg]

Why not just get a 100 ohm potentiometer or a series of 10 to 20 ohm resistors to swing your sunpro gauge to test it.
10 ohms get you right on the Full mark, 60 to 85 ohms puts you on the Low or empty mark.

The link you posted says it right there.

[burdar]

I'm working on other things right now.  I haven't gotten back to this yet.  One thing at a time. 

[Jamiez]

You should be able to take the signal from a standard mechanical gauge, and based on the voltage relative to ground turn on or off a light.  You might need an op amp/comparator/relay and a handful of resistors depending on the voltages involved, but it should be pretty cheap to make.

I'll see if I can't figure something out after work.