Hello everyone,


Yes, I'm going to be ****-retentive here. I have a 97 Ford Expedition XLT 5.4L 4WD. My factory sensor is a one wire sensor. I purchased a 7 color oil pressure gauge from GlowShift that has a three wire oil pressure sensor included. The sensor has three wires connecting to the gauge (red, black and white). There is another set of four wires coming from the gauge (red, yellow, orange and black). Connected everything per the instructions and it works great. What I want is to somehow tie-in to the existing one wire circuit. Yes, I'm aware I can leave the old sensor installed and connected but this is not desirable or logical. I can get into the why and why not but rather not. Let's just say the original sensor cannot be used. All I need is someone experienced with wiring to provide some direction. Can I use a diode or some other setup to tie-in the new sensor/gauge to the original single wire to retain the dummy light? Also, does anyone know if the factory one wire system is indeed nothing more than a dummy light or if it in fact is wired to the ECU or PCM to transfer necessary data thus being required for proper system operation? Either way, I still want to tap into the single wire. Thank you for your time.

 

Do you have room ti utilize a TEE where the present sending unit is located and then you can use both the original set up and now your new set up?

 

Yes, there is plenty of room. I also have an oil filter relocation kit from MMR so plenty of choices. However, I don't want to run two oil pressure sensors or a tee. All I want is to use the new gauge and tap into the old one wire connection. Even if I have to add a dummy light.

 

Each system, warning light and add on gauge are two separate systems and cannot be on the same sensor electrically.
You need the present sensor to operate the warning light and if you want to use a gauge it has to have it's own calibrated sensor.
The warning light sensor works like an on/off switch while a gauge has to have it's own special sending unit.
As suggested, both sensors can be fed oil pressure from the same tee, but will operate independently.

 

On this particular vehicle the single wire to the oxygen sensor has to send data back to the PCM, right? Otherwise, how would the factory oil pressure gauge in the instrument cluster know what the oil pressure is? Would this not make that single wire also a signal wire which can then be tapped into the signal wire of the new sensor?

 

If we take this one at a time, maybe it will become clear.
My first question is , why do you think they included a sensor for the gauge you purchased? It is needed

If your vehicle presently has an oil pressure gauge on the dash , it has a calibrated sending unit to send that info to the gauge.All sending units are not the same and neither are the gauges.If your vehicle only as an idiot light , when that light comes on it is usually because the pressure has dropped to a warning point where damage can occur. Usually a vehicle with only an idiot light, has a switch or sending unit that provides a ground for the light to illuminate and as soon as the engine is started and oil pressure builds, the switch opens and the lamp goes out. Most vehicles will have either the warning lamp only or the oil pressure gauge on the dash, but rarely both.
Which does your vehicle presently have?

Maybe if I can, but will try.
The oxygen sensor circuit is completely separate from any other circuit. It does send info to the PCM which interprets that info and responds according to how it is designed. The oxygen sensor nor it's info is related in any way to the lubricating system.

There are networks in newer vehicles that have modules that communicate with one another and the instrument cluster can be one of the modules. There is no way the lubricating system is tied into this network yet. It can be done , but so far is not necessary and can add to the manufacturing cost and we all know what that means. Could this be what you might be asking?

 

I am already well aware of the information you provided. To answer your relevant question, there is a gauge and an indicator light in the instrument cluster of my vehicle's dash. For future reference, there will be no instrumment cluster of dash. However, I believe the oil pressure amount displayed on the factory gauge is a ficticious number as the needle does not fluctuate with RPM fluctuations. The new sensor obviously has a signal wire which sends current when there is oil pressure. I assume the signal wire stops sending current when there is no pressure. Having an accurate gauge to reference is great, but an alert system would be even better. I wonder if I can splice into the signal wire, switch or sending unit (whichever applies) to make the light on the new gauge go out when oil pressure is lost _ or llikewise means to alert the driver. This will allow the driver to be alerted when they're not looking at the gauge via their periphial vision.

 

Why would you want the light to go out when pressure is lost?

If you choose, there are audible means available.to warn the driver when oil pressure is lost.

How is your new gauge obtaining it's info to register correctly?

 

Hold on to your thoughts, I have a little project for you.

Don't be chicken, open up your dash and trace the color wire that goes to the idiot lite and the wire that goes to the oil pressure gauge.since your vehicle has both..
This way you may find the answer you seek. Do you think you can handle that? Until you do that you will never know what you are working with .
A wiring diagram may not be detailed enough to get an answer that way.
Your motives are good, but your theory is a little faulty.

If you cannot obtain a satisfactory answer here, you could always consult with a dealership service dept and I believe you would be more than willing to share the solution, with the folks here.. What do you think? Thank you.