I have been looking for a answers for my oil level sending unit for wile . Even went to the dealer (O-NO) 5 line guys all stood around saying we don't know how to fix it .I pulled the plug at the sender the new sender and yes I have oil and yes I hit reset and yes drove the 04 Corvette for days still low oil level .. If the switch ( sending unit ) when working right ( Full oil ) is open and when the oil is low the switch is closed goes to ground and back to the PCM telling the PCM something is wrong cause the oil is low and is closed the sending switch witch then goes to ground . If you unplug the thing how can the pcm see a grounded condition if no single is going back to the PCM.. Unless the wire going to the sending is shorted out and is grounded to something giving a single to the PCM that something is wrong.. I got to be missing something.. Oil is not one of them I got oil .. Anybody ..Thanks.. O-No PCM got Al-Timers..LOL Driving me nuts..

 

I don't get it either. Anybody ..Thanks

 

I think you might have your answer, the lead is grounding on something ???? Do you have access to a schematic ??

 

In hand . Could the PCM be saving the info ,the wrong info ?? I don't think so ..

 

I guess I will have to trace the BRN. brown wire coming out of the PCN and see what is going on I don't think this will be easy thing to do ,if it was a stand alone wire would be easy I'm thinking it goes into the harness and I got to strip it to find it just might go straight to the PCM and find it there and unplug it from the PCM unless it's in a big plug with 10 others or might just cut it ,rather not have it working that coming on every 5 min.. Thinking.. or might tie into it at the PCN and run a new wire back to the plug something.????

 

Try a continuity check. Unplug the connector at the sender. If the wire in question goes straight to the pcm from the sender, unplug the pcm connector (whichever one it is - red connector or blue connector) then CAREFULLY insert one DVOM probe into the correct cavity (use an adapter of some kind or paper clip if needed - do NOT jam a probe into the pcm connector socket), then connect the black lead to ground (engine block, frame, etc)
If you can make secure connections, try moving the harness around a bit to see if there's an intermittent short to ground as well.
Connect both to ends of the wire and check resistance too. Should be zero or damned close to it of course or get a tone in continuity mode.

HTH

 

Good Advice !!!!!!!!!!!

 

Thanks for the info ,cutting the wires was a little racial I guess . Yes I'll have to test it all out .How hard could it be just a short wire going to the PCM .How getting to the PCM WOW what a pain ..Thanks for the info ..

 

Remove the RF wheel and access the pcm via the plastic closeout panel at the rear of the wheelwell. IIRC, there are about seven or eight 7mm screws. Not too hard to do.
Btw, I haven't looked at a schematic to see the routing of the particular wire you're interested in, so you'll need to confirm that of course.

HTH

 

http://ls1tech.com/forums/stereo-ele...u-pinouts.html This is for a 97 wire #76 the 04 wire # is 70 brown in the blue connector so going straight to the blue connector and find the # 70 wire in the and test from there . I have the wiring deal just shows it going to the PCM ,its hard to see it runs back to the fire wall then just disappears I am thinking it goes into the harness if so and there is a prom. with the wire I going to just tie into it from the PVM and run a new wire to the plug .. Its tight back there ..

 

Normally, these type circuits are wired fail safe. That is, if the wires
are cut, or the sensor is disconnected, the is a fault condition (Low Oil Level). The sensor would be closed in normal mode and open in fault.
Even if the circuit is wired opposite, grounding the Brown wire at the switch and opening it, should show a change in conditions. This
would show a bad sensor or wiring/PCM problem

Larry

 

That's close, but as a buddy and I have learned is backwards.
If the wires (sensor) is open, that's the "normal" (full of oil) condition.

Once the sensor (wires) contacts contact eachother(ckt closed) occurs, continuity from GND provides a path from GND to PIN 70 (C1, the blue one on the PCM) therefore providing a path from GND, through the sensor, to PIN 70 of C1, sending the LOW OIL alert to the DIC.

So, eliminating the sensor, thereby twisting the BLK and BRN wires together (thinking full oil) / (float making contact) would extinguish the LOW OIL condition still results in the LOW OIL alert.

Here's the thing. Once the "float" makes contact, that = LOW OIL=sends GND to PCM=pcm send alert to DIC. ABNORMAL condition=closed ckt between GND and PIN 70 (BLK to BRN).

Normal condition is, an interruption between GND & PIN 70, meaning, the oil has floated the float causing a resistance (> 0-ohms to ground) breaking the GND to PIN 70 connectivity=no GND to PCM=no alert to DIC.

We've had the BRN and BLK twisted together, had the CKT wide open, and continue to get the alert.

Ck document ID:1210842 schematic. The LOW OIL alert is a make or break ckt.

If the ckt is made (continuity) = LOW OIL alert = PIN 70 at GND

If the ckt is open (not made) = resistance = not the absolute GND reference the PCM is looking for at PIN 70= no contact through sensor=incomplete ckt to the alert thrown to the DIC=NORMAL condition.

It's odd, kinda "reverse floatation thinking", but, that's where we are.

The only other possibility is that with all wires, and sensor "open" the BRN going back to PIN 70 is catching a ground due to chaffing, short ckt to gnd or... is seeing enough "GND" "potential" to make the PCM see what it thinks is enough GND to complete the alert ckt to the DIC (which, as you know is a function of the PCM, at this point in the discussion).

 

Long story short, if PIN 70 at the PCM is recognizing GND, you will get the LOW OIL alert. If the cabling to PIN 70 is eliminated, (open ckt) and you continue to get the alert... there has to be a short at the harness, C1, the other pins to the PCM (to GND) say maybe, PIN 69, 71 or whatever other pins are nearby, or, the LOalert is dysfunctional within the PCM. That's all it can be, logically thinking. I suspect PIN 70 is recognizing what it interprets as GND The cause is what? Instead of ripping apart anything near the PCM, what I would do is check G105, and the other "Ground Packs" that are prone to troubles. Atmospherics, weather, what ever...
I can send info on those locations, etc...
"Digital Corvette" indeed. Impedance, resistance, "normally-open vs normally closed"... etc..

PIN 70 is recognizing GND, plain and simple. Oh, the BRN wire. = Abnormal = alert = LOW OIL level=BRN to GND. (BLK to BRN twisted together)

As stated, with all connections to PIN 70 open (NORMAL) and you still get the LO alert, it's either the pins around PIN 70, the C1 pins going thru C1 to the PCM, or the mating of C1 to the PCM, or, the PCM itself.

 

BLUISIDE is my ELE. bud and we have been looking in to this for as you can tell for days and this what we came up with very hard to get any info the this even from the dealer ,been there done that nothing ,buy a new oil deal @$60.00 no have 3 no something else so we just got all the info we could and did some test and tomorrow going to get at the PCM and test some more ..The plug might be all messed up from 12-14 years for driving and be grounded at the plug might just need to be cleaned up ??? All most can say is buy a new plug or I have a new plug or unit and worked for days and bam back on . This is not hock us pock us things work for a reason or don't work for a reason as last resort removing it from the 04 .. The sending unit is a joke at best .. Anybody know something I don't witch is not hard to do .. What you got.. Thanks..

 

Thanks for the info!
Bad engineering to wire it that way. Next oil change, I'm going to
test mine.
Thanks,
Larry

 

Hey LW, I don't disagree with you, although, if you think about it (given enough time and experimentation) the "wiring" isn't the issue (until proven to be so), it's the dadgum "sensor". I thought full oil = normal = float/sensor = closed ckt. Apparently, the opposite is true, once looking at the schematic. Once the "float" makes contact, the = LOW OIL = completes ckt = GND is recognized at PIN 70 = PCM shoots alert to DIC via internal circuitry.

I guess you could think in terms of "reverse flotation" where full = closed, normal (which in this case abnormal)
Also, where empty = opened, abnormal (which in this case is normal).

Gonna find out real soon, tomorrow.

My bet is, given the structure and composition of the parts of the sensor, inside the "float" (which looks to be plastic from the outside) there is a conductive material (kinda like a "steel belt in a tire, if you will) that when the float stops floating, that material closes the two contacts, dead short, BRN and BLK wires contact, provides GND to PCM, and the LOalert arrives on your DIC. Crappy "sensor". The wiring is nothing more than a medium by which to provide continuity or voltage.

Just a guess.

 

Where's Curlee and VettemanJack when ya need'em? So, it's down to this, eliminate the BRN wire from PIN 70 at the PCM. That removes from the equation that the BRN wire is "catching a GND condition" either by wear, chaffing, etc.. In other words, PIN 70 is wide OPEN. (Normal condition, no GND to PIN 70). If after that, the LOalert continues

 

Never has so few done so much for so many anybody writing this down ?? LOL What a pain but the light coming on non stop is a real pain also.. I'm going in ,put the dogs under the porch hide the kids have the ladies boil some water..

 

Further testing and elimination(s) have revealed two oddities.
1) there are 2 schematics showing the LOalert ckt N/O and another showing it N/C, given everything else is 100% (wiring, pins, connectivity, etc.)
2) all assumptions aside, we will ground P70 just before the PCM directly to GND eliminating any sensors, switches, BRN wires, BLK wires, etc..

The next step is to take P70/BRN directly to a known good GND reference just outside of the PCM

Kinda goes back to the, "ya gotta bad ground" conversation, doesn't it?

On this particular ckt/schematic, there are two scenarios (for "normal" operation) OPEN/CLOSED It's a GND or NOT to P70/BRN. Period. If all the BLK and BRN wires are 100%, the OPEN/CLOSE is determined by the pan sensor/LO switch. If however the BRN wire is open, the PCM will never see GND. To be continued..

 

So, we now have two diagrams/schematics. One document shows the oil LEVEL switch Normally Open (NO). The other shows it Normally Closed (NC). Well, after further testing, it's been determined the NC schematic is "normal". We haven't "fixed" the car back to OEM, but the good news is, we think we know the cause. P70/BRN at the PCM requires a GND=no LOalert. So, we cut to the chase and eliminated the LOsensor, and wiring, took P70/BRN directly to GND right outside the PCM. So far so good after 10 or so ignition cycles (uncharted territory).

What was causing us troubleshooting issues was the 2 different schematics, and moreso, a BRN wire that does not have continuity from the pan to P70.

A few more ignition/warm-up cycles will tell. Now, to get back to OEM, (in this case) would require a replacement BRN wire from P70 to the oil LEVEL sensor at the pan. Previous postings were in thought of the ckt being NO, instead of NC. Running NC now, and time will tell.

Will update as the car provides information. Hopefully by Saturday. To be continued...