Tj oil pressure gauge

jkp said:

The "oil pressure gauge" in your '05 is nothing more than an idiot light. The "sending unit" is a switch that closes at something like 5 psi. When computer sees the switch close, it moves the needle to mid-scale.

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Base on that logic, I guess I would disconnect the switch check for continuity and have someone start the engine. See "if" the switch is actually closing. 'Might want to also re-check the part number of the new switch-sender and see if it's the correct one they sold you.

jkp said:

The computer moves the gauge around based on RPM. Notice that it does not change position based on hot or cold oil. A real gauge would. This is a result of people comlaining that their oil pressure is "low" or "high."

From the FSM:

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Engine Oil Pressure Message - Each time the
cluster receives a message from the PCM indicating
the engine oil pressure of a 2.4L engine is above
about 0.2 kg/cm2 (3 psi), or of any engine other than
a 2.4L is above about 0.4 kg/cm2 (6 psi), the cluster
moves the gauge needle to the middle of the normal
range on the gauge scale to represent the engine oil
pressure. The gauge needle will continue to be positioned
at the middle of normal range on the gauge
scale until the cluster receives a message from the
PCM that indicates the engine oil pressure is low, or
until the ignition switch is turned to the Off position,
whichever occurs first.​

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Engine Oil Pressure Low Message - Each​

time the cluster receives a message from the PCM

below about 0.2 kg/cm​

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2 (3 psi), or of any engine other
than a 2.4L is below about 0.4 kg/cm2 (6 psi), the
gauge needle is moved to the graduation at the far
left (low) end of the gauge scale, the check gauges
indicator is illuminated, and a single chime tone is
generated. The gauge needle remains at the left end
of the gauge scale and the check gauges indicator
remains illuminated until the cluster receives a message
from the PCM indicating that the engine oil
pressure of a 2.4L engine is above about 0.2 kg/cm2​

(3 psi), or of any engine other than a 2.4L is above
about 0.4 kg/cm​

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2 (6 psi), or until the ignition switch
is turned to the Off position, whichever occurs first.
The cluster will only turn the check gauges indicator
on in response to an engine oil pressure low message
if the engine speed message is 300 rpm or greater for
more than about five seconds.​

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It really pisses me off that this was Jeep/Chrysler's solution to customer complaints of low oil pressure. Seems to me, a blurb in the owners manual explaining how oil pressure reads at different temperatures and RPMs would have made more sense.

I wish it was warmer out, and I'd go outside and play with my oil pressure switch to see when the PCM samples the switch open/closed readings. What I'd REALLY like to do is find I way to convert my gauge panel back to a real oil pressure gauge!

EarthRunner said:

So how does one go about swapping the idiot gauges to actual working gauges? Is there a write up on this?

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Easy enough to add an additional (real) gauge. So far, no one has figured out or posted up how to convert the "idiot" gauge to a real one. The other option would be ....

http://www.scangauge.com/