I have a 2001 1500 with the sport package. I am having issues with my oil pressure (gauge only) Just to be on the safe side I replaced the oil pressure sending unit, oil pump, and the main bearings. Was not able to do the rod bearings because no one could get a hold of them for me. When the truck is at operating temperature and I am idling, the oil pressure gauge drops to 0 and the check gauges light comes on. This is very annoying since I usually hit every red light in town. If I rev the motor up to around 700-1000 rpm's the gauge returns to normal, so one day I let it sit with the gauge at zero and just listened to the engine. Everything sounds perfectly normal, you can tell it is getting oil, and as an extra measure, I pulled the sending unit off again to make sure there wasn't any sludge or build up in that tiny hole. Looking in the manual the ECM controls oil pressure AND the gauge, but the PCM also controls oil pressure. I'm stuck I don't know what I need or even if this is the right direction to solve the issue, but I want to make sure I don't have computer issues because I have family in Idaho and I don't want to drive 5 hours to get stranded because it breaks down finally. If anyone has had this issue, PLEASE HELP!!!!!

 

The electric gauges in these trucks are notoriously inaccurate. Get a mechanical gauge and check your oil pressure with that. It will be fine. Your truck is simply getting old and there is nothing you can do to boost oil pressure short of a high volume oil pump without rebuilding the engine. The motor will run fine for thousands of miles (mine and many others have) without a single oil pressure related issue.

 

PCM doesn't modify oil pressure, purely mechanical. The sending unit communicates with PCM though, and PCM handles the gauge in the dash. I would look at the wiring between the sender, and PCM. (ECM and PCM are two different terms for the same thing, when applied to our trucks.)

 

Truck is getting oil no problem, the oil pressure itself has no issue, it has the 5.9 magnum engine in it new main bearings, oil pump, sending unit, timing chain, head gaskets, plugs, wires, cap and rotor, etc. There's been a lot of money put into this truck if you get my drift. I am just getting sick of the light coming on on my dash and dinging every time I hit a red light. If I could disconnect the wiring and not have to worry about it I would. I know it's electrical, I just don't want to replace the computer, and quick question...Anyone know why in the hell they put the computer under the hood? It's nice and easily accessible but I'm so used to them being under the dash in the damnedest spot to get to...

 

Seemed like a good idea at the time??

On mine.... when I disconnected the sending unit to put the mechanical gauge on it, I don't think the light came on... even with the engine running..... I think.

 

I have the factory gauge disconnected and use a cheap mechanical gauge. My dash gauge just sits as if the power is off and there is no oil light. If you go with a permanent mechanical gauge get the copper line as it is much better than the plastic stuff.

 

Have you dropped the pan and cleaned the pickup tube?

 

I'll have to check out the mechanical gauge, and yes I have dropped the pan, a few times actually. When I changed the oil pump, I made sure to clean the screen and the tube out very well, and then had to clean everything up again when I replaced the main bearings. I'll let you guys know what I end up doing to fix it, thanks for all the help!

 

Installed the mechanical oil pressure gauge and it reads between 15-20 psi at running temp when truck is idling. when accelerating it goes up obviously, and at cruising speeds (55-60 mph) it was reading about 35ish. oh and installing the mechanical and removing the oil pressure sending unit the gauge on the dash does stay at zero and the check gauges light stays on but it only chimes when I turn my truck on which is fine by me. Now question. Does anyone know what my oil pressure SHOULD be at? Something doesn't seem right to me because when I had the sending unit in there instead of the mechanical, the dash gauge said I was sitting at just above 40 psi when cold, and just below 40 at running temp, at an idle. The mechanical like I said is saying 15-20 at idle/running temp. Ideas???

 

Anything over 10PSI at idle is "acceptable"...... beyond that, about 10 pounds per 1000 rpm is the general rule of thumb. Up to a point anyway. 35psi at what? around 1500 to 2000 RPM is 'ok'.

On my truck, I was having oil pressure issues as well. Mechanical gauge verified that I was indeed getting zero pressure on occasion. (most of the time.... 10 to 15 pounds at idle, dropping to nothing when I stepped on the gas.) My problem turned out to be a clogged pickup tube. I replace the oil pump with a high volume unit (50 bucks at advance auto), and the mech gauge told me I had 80 pounds at idle, and it would climb just a bit with engine speed. Screwed the sending unit back in, hooked up the in-dash gauge..... and at idle, it reads 40 pounds...... going up to maybe 50 when I step on the gas. Lesson here? The in-dash gauge LIES!!!!