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Oil Pressure Switch (curious issue)

X

XJ96Classic

NAXJA Forum User
Location
Newport Beach, CA
I have a 1996 Cherokee Classic with the oil pressure switch located right above the oil filter.

So, the pressure gauge fluctuates a lot so I figure time to get a new sending unit.

The (badly working one) has one prong for the plug and the plug itself has one spot to accept a prong. the other side is a dummy.

So, Autozone, has the part but it has 2 prongs.. no worries.. one is prolly just a dummy i thought. I install it... nothing. I go and return it and get another one.. Nothing. Gauge is tached out at 80(which means no electrical reading is going on,same as being unplugged) I checked wiring and it all works. I install the original one again and it still works...

So, does this mean autozone is listing the WRONG sending unit for a 1996? Anyone?
 
to add to this... by fluctuation in the original one i mean it goes from 30 to 60 when i accelerate.. not that it jumps from 0 - 80 and all over the place like it would with a bad electrical connection.
 
XJ96Classic said:
to add to this... by fluctuation in the original one i mean it goes from 30 to 60 when i accelerate.. not that it jumps from 0 - 80 and all over the place like it would with a bad electrical connection.
Click to expand...

umm im pretty sure thats normal
 
Higher rpm = higher oil pressure, unless the engine is worn out and the pressure is hardly there at all.

Also, not a "switch", it is a variable resistor for a gauge and an on/off for an idiot light.

Oil pressure sensor, oil pressure gauge sending unit are better names.
 
joe_peters said:
Higher rpm = higher oil pressure, unless the engine is worn out and the pressure is hardly there at all.

Also, not a "switch", it is a variable resistor for a gauge and an on/off for an idiot light.

Oil pressure sensor, oil pressure gauge sending unit are better names.
Click to expand...

I agree.. and thats what i would call them too if autoparts stores called them that too.. but they dont.. they call the sending unit a SWITCH and the indicator a GUAGE
 
Some "chain" auto parts stores have one thing in common--more training needed for their counter persons.

I can live with regional differences, like ketchup and catsup, and age differences like panhard rod and track bar, but switch a variable resistor is not.

What a country!
 
I know them as an 'oil pressure sender and/or an oil pressure switch'. They are/work very different from one another ie; a switch will not work with the guage and the sender would not work with the light.

The plug on my XJ have holes for 2 wires but there is only one wire.

On the XJ, a properly working guage will go to zero when power is applied and the engine not running. With the engine running, it would show the oil pressure in the engine. A 4.0L with close tolerances usually show 30 to 40 PSI at idle and increase to 50 to 60 PSI when the RPM is raised. A worn engine, hot oil or a low grade (20) oil could show a lower pressure. (The numbers shown on the guages should be considered as approximate not absolute since the guages are not calibrated).

If the oil guage pegs to 80 PSI it indicates a short to ground in the wire from the sender to the guage or the sender itself is faulty or it is not the correct sender for the 4.0L .
 
techno1154 said:
I know them as an 'oil pressure sender and/or an oil pressure switch'. They are/work very different from one another ie; a switch will not work with the guage and the sender would not work with the light.

The plug on my XJ have holes for 2 wires but there is only one wire.

On the XJ, a properly working guage will go to zero when power is applied and the engine not running. With the engine running, it would show the oil pressure in the engine. A 4.0L with close tolerances usually show 30 to 40 PSI at idle and increase to 50 to 60 PSI when the RPM is raised. A worn engine, hot oil or a low grade (20) oil could show a lower pressure. (The numbers shown on the guages should be considered as approximate not absolute since the guages are not calibrated).

If the oil guage pegs to 80 PSI it indicates a short to ground in the wire from the sender to the guage or the sender itself is faulty or it is not the correct sender for the 4.0L .
Click to expand...


Yes, I agree with you on all of this...

my question still remains.... if the 'new' part did not work...both new parts... then is this part mislabeled at autozone... Is this actually the part for the 97+ or the 96- because the 96 is kind of a strange year... some things obdII, included .. are not inline with the older generation xj ...

Wondering maybe if this guy gave me the sender unit for a dummy light rather than for the gauge.....
 
joe_peters said:
Some "chain" auto parts stores have one thing in common--more training needed for their counter persons.

I can live with regional differences, like ketchup and catsup, and age differences like panhard rod and track bar, but switch a variable resistor is not.

What a country!
Click to expand...

AUTOZONE:
Duralast / Oil Pressure Switch
For your 1996 Jeep Cherokee 4WD 4.0L MFI 6cyl
6.jpg


NAPA
Oil Pressure Gauge Switch
103684.jpg


Kragan:
Master Pro Ignition Oil Pressure Switch
Part Number: S4133
8113.jpg



I am pretty sure that "switch" for the sender unit is the word most commonly used.... the first time i was there I asked for a oil pressure guage sender unit and the people had no idea what i wanted. I had to show them the part and they said 'oh// you want the switch'

Yea.. its a bad name for the part.
 
Sounds like they gave you the sending unit for the idiot light instead of the guage. Best way to do it is have them pull both sending units off the shelf and get the one that's the same as yours as I've seen numerous things at autozone mis-labeled.
 
You might want to try crimping the contact on the female plug a bit so that it gets a more snug connection with the oil pressure sender. It is possibly it is not making a perfect connection, causing the odd fluctuations from time to time.
 
It is near impossible wether or not Autozone gave correct sender without having one of both units in hand and compearing them. It is the case of the look alikes. Try compearing the number stamped on the unit instead of the box and trying them both. Or you could go to another store.

There is another way. Using an OHM meter, install the sender in the engine. Start the engine. Place the probes of the OHM meter one to ground and the other on the pin or wire coming from the sender. With the engine running, the switch for the light should have no connection to ground. The switch/sender for the guage would register OHMS based on the oil pressure and vary with engine RPM.

Unfortunately, I do not know what this OHM reading should be. I am sure some one here would have info on this.
 
Last edited:
joe_peters said:
Some "chain" auto parts stores have one thing in common--more training needed for their counter persons.

I can live with regional differences, like ketchup and catsup, and age differences like panhard rod and track bar, but switch a variable resistor is not.

What a country!
Click to expand...

<thread jack>As a ford guy, I love going into a parts store asking for a starter relay & have the CD (counter dummy) insist it is a solenoid.</thread jack>
 
There is an oil sensor/switch that is for gauges, and one for the dummy light. What you can do is pull the connector. When you start your XJ oil gauge should go to zero. ground the connector. If gauge pegs out, then there is a short in the wire.
 
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