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still can't get oil pressure reading

Old 05-30-2017, 02:15 AM
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Default still can't get oil pressure reading

I have been having trouble getting my 3 wire oil pressure signal to report correctly in HPTuners. I've switched the wires around with no luck, it either pegs out the reading on something like 130 or -15 depending on which way the wires are connected.

I'm going to try a new OP sensor tomorrow and see if that works.

411 PCM with the wiring done appropriately. Any ideas?????
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Old 05-30-2017, 11:58 AM
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128 views and nothing?
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Old 05-30-2017, 12:11 PM
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Nothing because no one knows WTF you are working on.
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Old 05-30-2017, 02:29 PM
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Sometimes I don't even know what I'm working on

Vehicle is a 90 Chevy truck with a bunch of other parts in it that didn't originally come that way.


It's a 2003ish LQ4 with a 411 PCM, oil pressure wired up as a 2000 vette PCM would be for the oil pressure sensor.

I'm right in your backyard, Guthrie OK
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Old 05-30-2017, 03:59 PM
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What OS in in the PCM?
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Old 05-30-2017, 04:14 PM
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I gave him the idea because I did it to mine.
I'm running a 99 Camaro OS.
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Old 05-30-2017, 05:11 PM
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It's a 411 PCM running a 3 bar SD operating system. I'm using layout files that Ron gave me.

Here's a short log of the oil pressure sensor readings with me switching wires around seeing if maybe I had some backwards, nothing seems to make sense so I'm wondering more and more if the sensor itself is bad.
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File Type: hpl
oil pressure.hpl (55.1 KB, 36 views)
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Old 05-30-2017, 05:36 PM
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Also figured I'd ask. What are you guys doing to feed oil pressure to your dash gauge?? Does that require another sending unit yet? That's the only gauge on my dash I haven't figured out.

I'd like to get oil pressure on my dash gauge as well as in Hptuners.

-----EDIT-----

I'm really confused about this LS style 3 wire pressure sensor. If I'm understanding this correctly, this is a SENSOR and not a SENDING UNIT like I'm used to dealing with.....
So I take this to mean that there is ABSOLUTELY NO WAY this sensor will give a signal to the PCM and ALSO give a signal to my original dash gauge? Do I have this right???

Last edited by ElQueFør; 05-30-2017 at 05:55 PM.
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Old 05-30-2017, 06:19 PM
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Originally Posted by ElQueFør View Post
It's a 411 PCM running a 3 bar SD operating system. I'm using layout files that Ron gave me.
Don't know what a layout file is. That is not a PCM term. What is the year and vehicle type in the PCM?
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Old 05-30-2017, 07:29 PM
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The term layout is what I got from Ron, as in the layout for the gauges and sensor inputs in the scanner portion of the HPtuners software suite I guess. The obd2 world is still a learning experience for me at this point.

The pcm says 02 v8 f body when connected to it in the scanner
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Old 05-30-2017, 10:23 PM
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What application OP sending unit are you using? What PCM pins are you wiring it to? I don't understand how you are trying to make it work with a 02 F-body OS. A 0411 with a 02 F-body OS has no pins assigned for OP sending unit input and uses a 2 wire sending unit with ground and output going directly to the cluster. A 02 Vette uses a 3 wire OP sending unit and is wired to the PCM. Those pins are either not used or reassigned to a different function with a F-body OS.
Attached Thumbnails still can't get oil pressure reading-02-f-body-oil-pressure.jpg   still can't get oil pressure reading-02-vette-oil-pressure.jpg  
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Old 05-31-2017, 11:23 AM
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Well....

You're not entirely wrong! The pins are labeled (Not Used) on every schematic I've seen for the FBody PCM at those pin locations. But whether it was used or not, the capability to use the input signal is still there.

Turns out all I needed to do was purchase a new sensor. See attached log showing oil pressure functioning.

Just to confirm...... A 411 PCM from a 2002 F body WILL report oil pressure to the datastream. Just have to configure it as a PID, wire it up to the PCM and most importantly USE A GOOD SENSOR!!!

My understanding is this. While not all 411 PCMs were factory equipped to have oil pressure as in input in the datastream, ALL or nearly all of them will accept it.


I am using a 2003-ISH stock truck oil pressure sensor (3 wire)... The Corvette sensor APPEARS to be the same P/N#. It is wired like a 2000 Corvette. Harness is a RED AND GREEN harness that I converted to a RED AND BLUE....

I bought a new sensor today to rule that out. The new sensor fixed it!

Wire the 3 wire oil pressure sensor to the 411 F body PCM like a 2000 C5 Vette and use a 3 wire sensor for either the Vette or a 2003-ISH truck.

IF you are converting a RED/GREEN harness to RED/BLUE like I did, then among other things, you will have to pin in a TPS for the conversion from DBW to DBC.

BOTH the TPS and OPS get their 5V REF from either pin 7 OR pin 8 BLUE. BOTH the TPS and OPS get their LOW REF from pin 60 OR pin 63 BLUE. It does NOT matter which pin is used at THE PCM. Just as long as the 5V REF and LOW REF are wired correctly on the corresponding sensor.

I can't really rely on any one application specific solution as my build is all over the place.... S475, stock LQ4(LS9 gasketed and ARP bolted)'90 chevy truck, LT1 T56 converted to LSx, LS7 clutch, custom aluminum DS, 454ss rear 4.88s&TruTrac diff, 4 wheel discs, Jeep steering shaft, 454SS box, 02 411 F body PCM(running 3 BAR SD OS), RED/GRN harness converted to RED/BLU,, ZR1 MAP, Walbro 450, decapped injectors, lots of braided stainless........I'm using PEX elbows to give me the 90* kick I needed to route my heater hoses up from the water pump and AWAY from my 5" downpipe and hotside. Solid motor mounts and poly everywhere else. etc.

Ron I've got to tip my hat to you yet again for helping me figure this out. Much appreciated.

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Old 05-31-2017, 11:25 AM
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The pins were open in my 99 Fbody harness so I added them connected to a 3 pin pressure sensor.
it works fine.
I realize that the Fbody simply had a dash mounted oil pressure gauge and was not read by the pcm.
But I also have a Corvette, same pcm so that's how I decided to give this a try.

It's a bit unique in that the pcm in the Vette assumes a 0-130 psi sensor. Most common sensors are 0-100 psi. But some simple math gets it to display correctly in the charts.

I rigged up a "T" connection with the sensor and a mechanical gauge to verify calibration.
I actually use the sensor to monitor fuel pressure.

Maybe the 02 Fbody OS won't allow this. I can't speak to that.

Chase, measure the voltage at these three pins. One should be 5v. One ground and the other is the output from the sensor. Hopefully you have the pinout of the sensor.
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Old 05-31-2017, 11:59 AM
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Ron, all appears to be working so far after plugging in the new sensor. Take a look at my log I posted above and tell me what you think.

When there isn't a sensor plugged in it seems to default to -15.7 PSI. With the old sensor plugged in it reads 130 PSI all the time so the sensor has shorted out or something. With the new sensor plugged in, it reads 0 PSI (or nearly 0) with the engine off and then reads 32-34 PSI after starting. There doesn't seem to be any conversion math required?

Do you have any pictures of your T fitting you built? I was just thinking about doing that. I'm going to hit the hardware store and see if I can find something in the plumbing section that matches the metric thread pitch of the LSx oil pressure sensor.
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Old 05-31-2017, 04:48 PM
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We were replying st the same time.
Glad it's working!
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Old 05-31-2017, 09:07 PM
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I'd assume your LS3 sensor is the same as LS1 and is a 130 psi sensor. So no math needed.

The "T" I built was just for testing. Remember, I was setting up a fuel pressure sensor.

For a mech gauge, you can just buy an adapter from Autometer and use the galley plug located at the left front of the block under the alternator.
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Old 09-07-2017, 10:51 PM
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Thank goodness for this thread. I searched for a couple days and finally found someone explaining that this does actually work.

Somehow my luck worked out for once as I believe I have an '00 Vette 0411 PCM.
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Old 09-12-2017, 09:45 PM
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You might need to enable it in the tune:


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Old 09-19-2017, 04:37 PM
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Originally Posted by HectorM52 View Post
Thank goodness for this thread. I searched for a couple days and finally found someone explaining that this does actually work.

Somehow my luck worked out for once as I believe I have an '00 Vette 0411 PCM.
Hey I'm glad that I could offer a little back to the community. It's usually ME asking for help with my stupid noob questions I have to ask in order to keep learning.

But yeah, I'm running a 411 PCM with a BLU/GRN harness that I converted to BLU/RED...... The original OP sensor I had was shot, replaced the sensor and wired it to the respective pins at the PCM and Voila!!! Datalogging oil pressure!!!!! I didn't have to do anything else becuase the layout files that Ron shared with me already had that provisioned.

So yes, you should be able to do this with your 411 PCM as well. Just wire it up to those pins at the PCM....
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Old 01-08-2019, 09:53 AM
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So i could get this working on my 99 trans am?
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