Oil pressure gauge

[CSM]

3 minutes ago, Nekkedbob said:

It is not a dummy gauge but the dash assy. is not high quality gauge set. What you see in mopar1973mans video is the voltage regulator on the back of the dash assy that has gone bad or a high resistance ground to the dash. The biggest problem with our dash is it takes a analog signal from the sensor and converts it to digital in the ECM and or PCM and then decodes it back to a analog value for the gauge set and if  tolerances are not kept very small (meaning more expensive ) you get just what we see. This is the biggest reason for the aftermarket gauge industry is that mfgs. put gauges that barely qualify as a useful gauge. Why do you think that you cannot find any accuracy specs for there stuff and they don't put but very few markings other "operating range". Many years ago I found the accuracy spec for speedometers ( I wish I could remember where ) from the D.O.T. and they only need to be within +or - 10 percent.

So, why does most everybodies truck do that when we fool the coolant sensor?  They are separate systems and could not be causal.  

[dripley]

I have to add this even if it cost me a dollar. When I took off from lunch today on a somewhat warm engine my temp spiked a little, around 193 just as I came up on a stoplight. When I stopped I guess the t stat had just opened and the temp dropped to 177, per my scan gauge. I happened to look at the oil pressure gauge and watched it rise slightly as the temp dropped. Then temp then leveled out and the oil pressure dropped slightly. That is the first time I have ever seen that. But it is the first time I ever watched them both to see if they were interacting with one another. I am going to have to watch them closer and be sure it was not just a fluke. I am just not thinking the oil pressure would change at those temps at idle.

[TFaoro]

Everyone who can fool the coolant temp watches this happen. Dummy gauge. 

To the OP, if the sensor is in fact a pressure transducer and you could find the voltage range, in theory you could set up a system to read the pressure and display it in psi. I have done this in labs, but I don't think it's worth it in this application. If you are worried you should just pick up a mechanical gauge  

[The_Hammer]

@TFaoro

I'm probably going to install a mechanical gauge. I know it's not that big of a deal but I'd like to have one. I ditched the drink ejectors and fiberglassed over the hole so I can fit two more gauges in there. 

[Mopar1973Man]

11 hours ago, Nekkedbob said:

What you see in mopar1973mans video is the voltage regulator on the back of the dash assy that has gone bad or a high resistance ground to the dash.

There isn't any voltage regulator on the cluster like old school. There are fully digital stepper motors commanded by CCD network data sent from PCM (fuel  and volt gauge), ECM (tachometer, oil pressure and coolant temperature) and ABS (speedometer) computers. That why to test the cluster you hold the trip pin down and turn the key on look for the word CHEC in the odometer window and release. This fires the cluster computer in diagnostic mode to test all gauge functions and spit out any error codes at the end.

So as for the weird oil pressure gauge behavior that function of one of the updated flashes that Dodge created. Like another one I've seen too is once the voltage hits 12.00 exactly the voltage gauge drops to 8 volts and chimes the CHECK GAGE light. Even though the voltage isn't 8 volts it's 11.99 volts and falling.

All data to the gauges is delivered on two wires. So basically in a nutshell the cluster is its own standalone computer.

Edited December 6, 2015 by Mopar1973Man

[The_Hammer]

@Mopar1973Man

I have a 96', I don't have the digital odometer. 

[Mopar1973Man]

I'm referring to 98.5 to 02 cluster and the oil pressure gauge issues.

94-98 clusters should be oil pressure sender to cluster direct wired. Still in all I would still test with a mechanical gauge.

[The_Hammer]

11 minutes ago, Mopar1973Man said:

I'm referring to 98.5 to 02 cluster and the oil pressure gauge issues.

94-98 clusters should be oil pressure sender to cluster direct wired. Still in all I would still test with a mechanical gauge.

That's the plan, if for nothing else but peace of mind. 

[GSX455]

I have no oil pressure, and I have replaced the oil pressure sender unit.   How do I get the Check Gauges light to turn off on the dash?

Thanks,

GSX455

[Mopar1973Man]

OBDII code reader and use the ERASE feature. There is no other way to erase codes. Not even disconnecting the batteries will work.

[AH64ID]

AFIK all 1st and 2nd gens have oil pressure senders and not switches; however, there is a flash for the 24V crowd that turns the actual oil pressure gauge into a 3rd gen dummy gauge. IIRC any 24V with the latest software will get this "feature". Flashing your truck with a Smarty, and possibly other programmers, will get you the latest software. 

 

 

So you guys are all correct. Some of your gauges work and some don't. 

 

AFIK the dash gauge on all 12V's works properly. 

[Me78569]

My truck has been flashed with a smarty and I still have a working oil pressure gauge.

 

I think the switch vs actual gauge is in the PCM not the ECM., 

Edited April 5, 2016 by Me78569

[Mopar1973Man]

10 minutes ago, Me78569 said:

I think the switch vs actual gauge is in the PCM not the ECM., 

 

Actually ECM.

 

PCM does nothing with the Oil Pressure value. The ECM reads the data and transmits the data on the CCD Network. It's up to the Instrument cluster to listen for the data and display the data as the cluster is programmed to. PCM doesn't have any connection to the sender so it can't process the data.

 

 

[Me78569]

so when they did the upgrade did they flash the ecm and rewire the sensor?

 

Or does the smarty not load that saved flash onto the ecm?

[Mopar1973Man]

I can't speak for Smarty. I'm pretty sure that Smarty does not download the entire flash file. That takes quite a bit to do after seeing it done on a 6.7L. So I would have to assume that when returned to stock Smarty flashes with it own update.

[Me78569]

Smarty has it's own flash file that they say is  "best" for the truck.   I dunno what they do for the sensor so.  Didn't do anything to my oil pressure gauge. 

[GSX455]

20 hours ago, Mopar1973Man said:

OBDII code reader and use the ERASE feature. There is no other way to erase codes. Not even disconnecting the batteries will work.

Well, I turned the key on and erased the codes with the OBDII tool; as I drove the truck, the Check Gages light, came on, I cleared while it was running, and the light is still on, maybe I bought a bad pressure sensor, or could it be the harness pigtail?

Edited April 5, 2016 by GSX455