Oil pressure gauge zero & check gauges light on startup

[cd36]

So we just got a 2005 Ram with the 5.7L and if it has sat for a while it seems that when we first start it up the oil pressure gauge will not register anything, and the check gauges light comes on. If we shut the truck off and start it again it always shows oil pressure, and it has never done it to us while driving.

While doing some searching I discovered that the oil pressure gauge isn't a true gauge and it is just an estimated reading, and that there is basically just a switch that senses if there is pressure or not and if there is pressure it puts the gauge to half way. I found that what I'm having is a somewhat common issue and replacing that switch is the cure.

So I go to order a switch and turns out there is two different oil pressure senders, one for a light and one for a gauge (some places say the gauge is a 3-wire version). Well when I looked at where I thought the oil pressure sender was (just above the oil filter) it has a sensor that looks like its the one, but it only has one wire going to it.

ANd heres the kicker, I unplugged that sensor, and started the truck and sure enough it registered as 0 oil pressure and the light came on. I shut it down and started it again and strangely enough the oil pressure went to halfway and no lights came on. So now I'm puzzled at what that is above the oil filter, as I'm reading pressure with it unplugged. Is that just oil temperature?

And does anyone know where the sensor is for the oil pressure gauge? I looked around and couldn't find another oil pressure sender anywhere. THanks!

 

[cd36]

So I went out and did some more troubleshooting. The oil pressure switch above the oil filter is definately just a switched. It is closed when it is low pressure, and open when there is proper oil pressure, so that is why when the wire is unplugged the gauge still shows a proper reading.

The weird part is with the oil pressure switch unplugged, it should always show good oil pressure on the gauge as the circuit is never closed, but I could still get it to show no pressure with the switch unhooked, shut the truck down and started it again, and it worked fine. If I grounded out the one wire that goes to the switch I could make the gauge go from normal to 0 and back again.

I'll have to look over the circuit diagrams and see where that wire all goes to, does anyone have access to a PDF service manual? I'm wondering if that wire just goes straight to the instrument cluster, or if it goes to the ECU first or what.

 

[MXL4]

Did you ever find an answer for this? I have a 2003 2500 with 7500 miles (that's right 7500) and it has just started to do the same thing. Every startup, warm or cold, there is no movement in the gauge and the check gauges light comes on. If i shut it off and restart it within 5 seconds everything registers normal.

 

[Brady Cousins]

So we just got a 2005 Ram with the 5.7L and if it has sat for a while it seems that when we first start it up the oil pressure gauge will not register anything, and the check gauges light comes on. If we shut the truck off and start it again it always shows oil pressure, and it has never done it to us while driving.

While doing some searching I discovered that the oil pressure gauge isn't a true gauge and it is just an estimated reading, and that there is basically just a switch that senses if there is pressure or not and if there is pressure it puts the gauge to half way. I found that what I'm having is a somewhat common issue and replacing that switch is the cure.

So I go to order a switch and turns out there is two different oil pressure senders, one for a light and one for a gauge (some places say the gauge is a 3-wire version). Well when I looked at where I thought the oil pressure sender was (just above the oil filter) it has a sensor that looks like its the one, but it only has one wire going to it.

ANd heres the kicker, I unplugged that sensor, and started the truck and sure enough it registered as 0 oil pressure and the light came on. I shut it down and started it again and strangely enough the oil pressure went to halfway and no lights came on. So now I'm puzzled at what that is above the oil filter, as I'm reading pressure with it unplugged. Is that just oil temperature?

And does anyone know where the sensor is for the oil pressure gauge? I looked around and couldn't find another oil pressure sender anywhere. THanks!

Did you ever find out what is going on with the gauge? I have the same problem

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