Code P0122

Hello, this code for the TPS (low circuit input). This may be a wiring issue with this code. You'll have to check the circuits to the TPS. The grey/black wire is the 5 volt reference wire. The black wire is the ground and the dark blue wire is the signal wire going back to the ECM. With the key on, not running. You can back probe the wire connector with a T pin and check the voltage. If you back probe the wire, put the voltmeter's black lead on the battery negative and the red lead on the wire you're testing. The black wire (ground) should have 0 volts. With the key on and back probed on the Signal Wire (dark blue wire) you can press the gas pedal down slowly and watch the voltage raise on the multimeter, it will be a low voltage near 0-0.5volts and raise to near 4.5-5volts. Try these tests and let us know what results you get. Also take off the air boot and check the throttle plates, make sure they are fully closed with the car off. Carbon build up on the throttle plates can cause them to stick open. But this code is pointing to a voltage issue the ECM is seeing and that's why its setting the code. I have added the full Diagnostic Procedure as well.

https://www.2carpros.com/articles/how-to-use-a-voltmeter

https://www.2carpros.com/articles/how-to-check-wiring

https://www.2carpros.com/articles/engine-idles-too-high

I back probed the blue wire multimeter set on 20 volts and I got a .01. opened the accelerator and no movement at all. One other time I touched the needle and it went everywhere but for the most part it's reading .01.

okay, that's a good first step. Does the grey/black wire have 5 volts with the other multimeter lead going to battery ground? With such a low voltage reading on the signal wire, i'm willing to bet your missing the 5 volt reference on the grey/black wire. Make sure you test with the key in the On position. If your missing the 5 volts, then we will need to chase down that issue. One other question, does the check engine light come on when you turn the key to "on", and then go off? It should come on for about 2 seconds then go off. That will tell you if the ECM (engine computer is being powered up). The last test is to check the grey/black wire with the TPS unplugged, so you'll be testing the harness side coming from the ECM.

Yes gray/black has 5 volts plugged and unplugged. The check engine light stays on.

Harness side of grey wire reads 5 with key on 0 with key off.

black wire w/ meter set on 200 ohms reads 6.6 unplugged from harness side reads 6.6 as well.

traced from plug back to connection right behind alternator touched pin in grey wire read 11.99 on both ends of the connection.

The grey/black wire reads 11.99volts with the other lead on battery negative? This is the same wire that reads 5 volts at the TPS sensor?

A side note, when checking a ground wire, (the black wire), you want to leave the meter set on voltage, with the key still in "on" position, you'll then want to back probe the black wire and other meter lead going to battery negative. This is called a voltage drop test. So you will be testing how much voltage is lost from the sensor to the battery negative. it should read almost nothing, 0.050 volts or less. Doing a resistance test will not show a problem on a wire, that might only occur when the circuit is "on" and loaded.

I'm not sure if you're on the right wire. Because if you're reading 5 volts on grey/black wire at the sensor to battery negative, You would be reading the same 11.99 volts at the sensor as well. If you get what i'm saying. Unless you're taking a reading across the connector, one lead on one side and the other lead on the opposite side. Then I would pull that connector apart and see if its corroded inside.

I think you're right. In a different light the wire looks more yellowish than grey but it still has a dark stripe.

Yeah, as the wires age too, the colors can get hard to distinguish between each other, but we're still on the right path here. The signal wire being out of range. I would go back and recheck the ground wire, if the sensor has the 5 volt reference, and has a good ground, then its probably another bad sensor. It happens more than you would think, but voltage drop that ground wire with the key on, so red lead on the black wire and other lead on battery negative. This is with the sensor plugged in. Try this test with just key on and running test and see what you get. It should be very close to 0 volts. The fact that you're not getting any reading while pushing the pedal down, that's our issue here. Does this car have a throttle cable going to the Throttle Body? Or is it just wires going to it? If it has no cable, then it is a drive by wire system. Meaning you may have a bad throttle body. If the car does not have a throttle cable, then take the air boot off the throttle body and depress the gas pedal, you should be able to see the throttle plates move with the key on. See what you get with testing the Ground (black wire) and watch the throttle plates move. See what you get there.

Back probed the blue wire when I touched the needle it read 1.63 accelerated and it was a steady climb of 4.42 then started dropping steady without letting off on the accelerator. Throttle plate not fully closed but slightly cracked open. I cleaned it with some carb and air intake cleaner and a rag got some grime out of it, not spotless but fairly clean. Cables move freely.

okay, that's strange that it started dropping off like that. How far down did it go? And with your foot off the pedal, really those throttle plates should be fully closed. Did you get to voltage drop the Ground wire at all? So you are getting a reading on the Signal wire now though it sounds like. it shouldn't be dropping off though. Does this high idle happen all the time? i'm just trying to narrow down the possibilities here. Either the throttle plates aren't closing all the way allowing extra air in, you have a vacuum leak, possibly a bad Idle Air Control Valve,

try unplugging the Mass Air Flow Sensor on the beginning of the Air Boot, take the air boot off, start the car, if it idles high, put your finger over the hole just in front of the throttle plates. See if the idle comes down. That's the hole for Idle Air Valve. We're a bit off track here because of the TPS voltage readings your getting. You can try replacing the Idle Air Control Valve, they're about $35.00 at AutoZone. They have a high failure rate. but i'm not %100 on that because I'm not really sure what voltage readings you're getting at the TPS.

It dropped back down to 1.60 but no lower. Back probed black wire key on it reads .01when touched. The idle is like sitting there revving the engine up and down but it's doing that on its own. The blue wire I opened the throttle body all the way and when it reached 4.42 it started dropping with me holding it open which to me was weird. Back probing with key on again, grey/black 5.01 --- black .01--- blue 1.56 upon touching needle 4.42 but this time it didn't drop at all until I backed off the throttle. 3 reading with the same results. By the way, I really appreciate you sticking by me this long and helping me. I started it still revs up high, kind of up and down. Take the air boot off between the air filter and mass flow sensor or at the neck of the throttle body?

okay good, at least your getting some solid readings now, I cant explain the voltage drop off like and hopefully its not an ECM problem, But for now we'll keep checking other things.
The hole for the Idle Air Control Valve (IAC) is right in front of the throttle plates, so it will be the neck of the throttle body.
So technically when you unplug the Mass Air Flow sensor, the ECM should go into a default fuel strategy and the engine should run okay, (This is on most cars, but i'm not 100% on Chevys) But i wanted to see if the idle would come down when you put your finger over the IAC hole. This hole just bypasses the throttle plates and allows the ECM to control the idle by moving a Stepper motor back and forth inside the IAC. If its stuck open, the idle should come down by doing this. If the car just stalls out, we're probably going to check for a vacuum leak. Do me a favor and take a picture of the engine layout and post it here, so i can direct you a little easier.
I am concerned with that voltage drop off though, reason being, is this Code p0122 is for a Low Input signal from the TPS to the ECM . I'm wondering about a possible bad ECM ground here as well.
I know it's a lot to take in at once, But I think while your messing around with the car, you may want to keep your multimeter set up on that Signal wire (dark blue wire). If you can with an alligator clip to hold your lead on the pin. These are one of my pair i use. Since you're going to be a pro at testing wires when we're done here.
So does the car surge when your driving? For instance when you have the throttle plates open with your foot on the gas? or does it go away? Reason i'm asking is a vacuum leak will go away when you open up the throttle plates and more air is moving in. Vacuum leaks will be more noticeable at idle.
So try your finger over that IAC hole, take me a picture of the engine, and monitor that Signal wire and see if the voltage drops off like that again. If it does we're going to have to start checking the ECM power and ground wires.

I should have added this, but having the Mass Air Flow sensor unplugged is going to set another code, so just ignore that when you have this rescanned for new codes. Have them just erase the codes, if you have any parts replaced.
I'm going to throw this out there right now, Here are the Grounds for PCM/ECM. They're right near the starter motor in front of the engine, so the front of the engine means where the main drive belts are. But check these Grounds, I saw this picture and they're all bulked together, probably on one stud with a nut on it. If there's any rust or corrosion, take the nut or bolt off and clean the heck out of this Ground location. I remember a car like this having an issue with the ECM and it was these grounds that were the problem.
They put all the PCM grounds together like this, and if one is bad it effects the whole lot of them. Black/white wires.

Sorry for all the edits here, Just to see if this works, if you do have a new TPS sensor on there, try unhooking the battery negative for a few minutes, the hook it back up, This will erase the ECM memory, lets see if that works. This is along the lines of erasing a code after a part is replaced,
I'm adding an installation tip I just found, I know it's for the 3.8L, but the 3.1L is very similar.

I traced the blue wire to the ECM and back probed it. It took a reading 1.59 - 1.62 that was with the key on. Opening the accelerator had no effect.

This is the ECM correct? If not what is it?

Never mind I know it isn't.

Okay, thanks for the pictures. Well we've found the real issue at least. Its strange that you're even getting any reading on the signal wire at all. I think you're going to have to check that 5 volt reference wire while this problem is occurring. My head is telling me you may have another sensor that is shorted out and pulling the 5 volts low or a corroded connection somewhere. the ECM needs a full 12volts to operate. I'm not sure its a bad ground.
The reason for this is, if you had a bad ground wire, the signal would be high because its not being pulled to ground, but since its a low signal, either that 5 volts is low, or power to the ECM/PCM is low. This is definitely not an average problem. I'm glad you've been able to do these tests so far. This is getting to be some tough diagnostics.

So the next step here is going to be checking the 5 volt wire at the sensor when you're not getting a reaction out of the TPS. I don't know if this is a problem that is always happening or if it is intermittent. Since you did have a reading at one point during all this,.

If you start the car, does the throttle respond while its running? even if it has a high idle?

I would even check that your battery has a good charge, because at this point with all the testing with just the key on, the battery is going to be low on charge. So start the car and let the battery charge up before anymore testing. Make sure at the alternator post to battery negative its charging at least 13.5-14volts.
I will be really embarrassed if this turns out to be a charging issue.

So next steps, charge up the battery, check that 5volts while the problem is happening, And is this the Base Malibu model or the LS model?

I'm giving you the power diagrams to check the ECM. So what you'll have to do on these, since there might be more some wires that are the same color, is just make sure the wire you checking has the same color wires next to it as on the diagram.

So the 1st Diagram is the battery voltage wire is an "Orange" wire next to it a Pink wire, and a Purple wire on the other side. The Orange wire should be battery voltage all the time (12v), And the Purple wire is Battery Voltage while the key is in the On Position (12v).
These are all highlighted in yellow.

The grey wire above those, you'll see, is a 5 Volt reference wire. Check all these after the battery is good and charged up.

The 2nd diagram is all 5 volt tests, Key On is fine for these.

The 3rd diagram is one 5volt ref, and two 12v ref.
I'm assuming you know where the ECM/PCM is because you said you traced a wire back to it, which is great by the way.

Just really make sure that battery is good, its really important that its fully charged for anymore testing. Let me know what you find.

And one thing, these tests we're doing are not loaded circuit tests. Meaning we're not stressing the circuits right now, which is what I would be doing in a shop. But for right now, just do these basic checks and we'll keep going from there. Doing these tests while the car is running would be even better, but if you're worried about the idle being all over the place i understand.
If everything checks out, check the wires while doing some wiggle tests on the harness, sometimes while moving the harness around a little, a problem will reveal itself.

In your pictures, the 3rd one you asked about, looks like an ignition module for the coils. You have spark, so go right to the ECM now. Its labeled as just below the left side of the dashboard, so driver side. Its going to have a ton or wires running to it like in the diagrams. I know there is 3 of them, but there just broken up that way. All the pictures run to the same ECM.
I really hope you didn't just get a bad part from the auto store. Its been happening a lot more lately. Just junk brand new parts.

Just wanted to throw more to think about, sorry for this, but while tracing wires back from the TPS to the ECM, check as much of the wiring as you possibly can. I know you've got an odd situation here. But any contact points where the harness touches any part of the engine or frame, where it can rub threw after years of vibration and movement.

Hey, I was going through your comments here, if you put the old TPS sensor back on the vehicle, I really think you should try a new sensor. We get brand new sensors that are bad all the time. Try another TPS and have the codes cleared or disconnect the negative battery cable for a few minutes. You've tested enough that we should have come across a problem by now. Bring the new TPS back that you bought and tell them its bad and get another and try it.
The memory needs to be erased with a new sensor in there. If you still have problems at least we can absolutely rule out the TPS.

I had a reply/sermon/speech aka; long post and tried to post a video so you can hear for yourself what it sounded like and deleted both. I think I might be done for the night, at least for a while. Too frustrated at the moment.

Morning Al,

Could it be the TPS and Air Idle Control Valve both? I did disconnect the battery for about 10 minutes and the check engine light cleared for a bit. Did I understand you to say I should back probe the blue wire with the engine running?? Also test the EMC under the dash and connect the black with to ground like maybe the door hinge and with the key on? There's been a lot to digest.

Yes, i understand it's a lot to take in, it's just as frustrating being on this end not seeing the car for myself. There could definitely be more than one problem here. But I think if you try another TPS, at least we can completely rule that out. They aren't making decent electronic parts these days. The car is 20 years old, so almost anything is possible by this point.
I would try another TPS, give the throttle plates a real good cleaning. And i'm not sure if you tried putting your finger over that IAC hole in front of the throttle plates and if that brings the idle down.

You can back probe the dark blue wire with it running and see what the voltage is doing or if it does that lose of voltage like you were describing. If that's really happening, it can be a bad sensor, a lose of that 5 volt reference, a bad wire somewhere, or another sensor is shorting out bringing the 5 volt ref down. You can see why its tough to figure this out from here.
If you're back probed at the ECM on that Signal wire and there's no Voltage increase with the pedal. That's our issue.

For the code p0122 to set, the ECM has to see the Signal from the TPS drop below 0.10-0.17volts. for more than 1-6 seconds.
As for your grounding question, you can try the door for a ground, but you have to make sure its really a good ground.
So if you're at the ECM, try the door as a ground and check the ECM (orange wire) power feed. If you have full battery voltage there, you're good.
Sorry this is so frustrating, if you lived down the road I would have driven over to your house by now. But diagnostics is tough work if you haven't been doing this for 20+ years.
I figured trying a new sensor would lessen some of the headache.

I just know this code sets because of an off voltage reading. When I look up the criteria for the code there's a list of things it can be, plus a voltage variation for the TPS. Ill show you the list so you get the idea.
Do you hear anything that sounds like a vacuum leak, it would be a loud air rushing in type sound, but it may be difficult with such high rpms.
I'm putting up the Diagnostic Procedure from our information source, but it calls for a having a scan tool to watch the data and check the freeze frame info as well,
You can try this method, i'm just not sure how far you will get with it, it talks about jumping the 5 volts to the signal wire, and if you do that wrong, you can fry ECM parts. So i don't recommend it.

Yes, I can imagine it has become a headache for you too. Yes I put my finger over the hole but I'm going to have to try again, I don't think I had it completely covered but IO felt vacuum on my finger. Can't say I noticed a change. I'll try another TPS too. I'm out of intake cleaner but have brake parts cleaner but that will be too harsh correct? Battery is only a few months old and reads 12.46 alternator I forget what that reading was so I'll have to do it again. Vacuum leaks, I didn't hear anything but if there is one the engine drowned out the hiss. I'll redo a couple of test then get a new TPS some intake cleaner and scrub the intake down good maybe have my wife listen with the stethoscope since she hears better. I'll do these things and see what happens.

I figured it would be hard to notice any changes with an engine revving up 4,000 RPMs, it would be hard to hear anything. If you did feel some vacuum, that means the IAC valve is open somewhat, if it was stuck open the idle would come right down and probably stall the engine out.

What you're describing with the idle going up and down, is the ECM hunting for the correct idle but not being able to achieve it.
If there is some vacuum at the IAC that's going to be expected, since the ECM is using it to try to correct the idle condition. But there shouldn't be a real strong vacuum.
Ill bet that IAC is opening and closing back and forth trying to correct for something.

Are the throttle plates completely closed? They really should be, if they're not, there would be some slack in the throttle cable. This would indicate the plates are staying open due to carbon build up. But I remember you saying the cable was tight at one point.

This just keeps bringing me back to that voltage drop off on the TPS signal wire.
The ground reading was ok and you had the 5 volts it needed.
Unless that Signal wire is rubbing on something metal and is shorting out to the frame or engine block or is corroded in a connector. That would pull the voltage low for sure.
I would check every inch of it if possible, all the way back to the ECM.
Sometimes you were getting a reading with pedal and sometimes not it seems.
Try a sensor so i can get that part out of head.

It cant hurt, we've been at this all week. Something has to show here eventually.

I bought another TPS sensor from NAPA, cheaper than AutoZone. New TPS and AIC and it still wasn't right. I tore it all back out and sprayed and wiped out the throttle body as far back as I could with my finger. If it isn't clean now it never will be. Even with everything off, battery disconnected, the butterfly isn't closing all the way. I stuck a mirror in there and didn't see anything that might be holding it. I'll put everything back together tomorrow and try to back probe that crazy wire back to the emc and see what I can get. I can't wrap my head around why the butterfly won't close completely even with no power. I thought about removing the EGR valve to see if it's gunked up. Debating whether I want to do that or not.

okay. well, I'm glad you got all that done though, that helps rule out a lot here. How much is the throttle plate open? and if you were to loosen up the cable do you think you can get it closed all the way?
As for the EGR, its probably got carbon build up, taking the valve off and cleaning out the ports is always a good practice in general. The ports that go inside the intake manifold can be very hard to clean out sometimes. Depending on the design of it. Thank you for trying another TPS.

Checking that dark blue wire at the sensor is a good idea, either that voltage signal is incorrect, or its those plates staying open when the ECM thinks they're closed. I'm wondering if the bearing that holds the plates is binding up or something along those lines,

If you loosen up the cable and it doesn't close and you cant clean it anymore, Id look into a new throttle body or at least at the auto parts store have them show you a new one and check the difference.
But we do need to verify that voltage signal.
The throttle plates (butterfly valve) aren't controlled by anything except the cable on your car. Looking at the wiring diagrams here, its just the cable controlling that. Possible the cable is binding up,
You can pull the throttle open with your fingers and unhook the cable without having to do much else. See if that closes those plates. Don't be afraid to take the throttle body right off the car and investigate.
You're right there man, I know this has been a huge pain all week, but you've done good work. Doing the TPS and IAC at the same time was a good idea, id leave the new ones on there. Then you wont have to worry about those in the future.

Okay, from here, disconnect that throttle cable first. see if the plates close.
If the cable is binding up or for some reason the cruise control is holding the cable keeping the plates open, we have to know the plates will close on their own.
Then we can determine if its the cable or something else..
Do that first tomorrow or whenever you have a chance, Just pull the throttle forward with your hand and you'll see you can slip the cable off the throttle body.
If the cable doesn't do it, check the stop screw on the plates, if someone has messed with it.

I back probed the blue wire from harness this time using a paper clip and it read 1.68 an opening the throttle it went to 4.53 and eased down letting off on accelerator. I got intimidated once I got under the dash looking at all those wires I couldn't tell the difference between some of the colors between grey/black and beige or dark blue and purple or a dark green. I couldn't tell what some of the colors were for sure so I didn't probe from there. I don't see anything that looks like an issue with wires touching or exposed. Butterfly still looked cracked, I sprayed a squirt of silicone lube on the accelerator cable under the dash and tried to work it in a little but it didn't seem to help. Battery's at 12.28 going to start it and see what it does. New TPS new AIC so here goes. I might let it run for a few then shut it off, let it set then start it again so the computer can learn the idle speed.

No, stepping on the gas pedal doesn't respond. All it does is sound like a ton of air being dumped into the throttle body but the rpms don't change, still loping. Strong smell kind of like a hot oil and exhaust.

Idles between 35 and 4000 RPMs so it has come down about 500 RPMs.

I think I'll pull the EGR valve and see what it looks like. Not sure if that has anything to do with the idle or butterfly staying open but maybe that's the cause of the smell. Can't hurt.

So pushing on the pedal, there's no response at all? has it always been that way?
And 1.6v at idle is too high for the TPS. But if the throttle isn't responding at all. that's a whole different story. The smell might be the engine running too rich if you don't see and oil leaks.
The throttle response is your issue, if your pushing on the gas and nothing is happening with it running, its either gone into Limp Mode, or you may have a bad ECM.
Under the dash on the driver side, look for the ECM. Its going to be a big flat silver box.
Use the wire colors in their order and match them up match. There are 2 big connectors on this ECM. I'm putting up all the diagrams for both connectors. You'll have to get a real good flashlight so you can see the correct wire colors.
The 1st picture is the 2 connectors,
the next 3 are connector 1. its a blue color
and the last 3 are connector 2 is clear looking.
You're going to have to find it and check the power inputs and grounds to it.
Connector 1 (blue) has the main power feed for the ECM. The Orange wire (Pin 20)
The ignition switch power is Pin 19 Purple wire. Both these should have battery voltage.
The ECM ground is on Connector 1 Pin 16 Black/White wire.
All the 5 volt refs are on Connector 2.

How long has the pedal been unresponsive? was that from the beginning of all this?

I just checked the pedal the other day so I'm going to say probably from the beginning. I kicked it a couple of times to try to get it to come down like in the olden days when all of this started but I never looked at the tach then my focus was purely on the sound. The only thing that happened when the pedal is stepped on or throttle opened is a sound like a gush of air being dumped into the throttle body and maybe a slight brief second of revving. There aren't any oil leaks. To test these do I just ground out the black lead and red on a back probe with a pin in the connector side with key on or key off? Also is sticking a pin in there okay to do? I don't want to unplug the connectors because my Haynes book says the ECM would have to be reprogrammed at a shop (it's an old book) or are they sold already programmed?

Limp mode sounds like it should be self explanatory. What numbers should I be reading on my multimeter, should I be seeing 12v on the blue power wire to the emc v?

It took a while but here's what I got on the connections from the connection side. I couldn't go in from the wire side because it's all encased in plastic and I couldn't get in there, I didn't want to break it trying to separate the halves. C-1 pin 20 battery positive voltage 12.34, pin 19 ignition voltage 12.03, pin 16 ground -0.02. C-2 pin 66 T P Sensor signal 0.01 and the battery is down to 12.19 now. C - 2 was harder because the wires didn't have much give to turn and being clear reflected more light back. What I saw that I think would be off is maybe c-1 pin 16 my .signal wire -0.02 and on c-2 pin 66 my TPS signal 0.02. What that all means though I'm not sure. One thing I didn't think of doing when I was on 16 was press on the gas pedal and take that reading. I was trying to keep a good ground.

okay. For trying to keep a good ground, using an Alligator clip helps a ton. You really need to keep the ground (the black meter lead) as solid as possible. Because with the meter set on a voltage scale, and not having a good ground, the meter is just going to read 0 or 0.01. So have a good ground is essential. Plus it makes it easier to test when you don't have to hold on ground lead all the time.
If you plan on doing repairs yourself in the future (which i recommend you do, because you will save yourself a lot of money). You should invest in a pair on meter leads that have clips on them that can be removed if needed. I recommend (https://www.aeswave.com/)
This is where I get all my leads for my meters and lab scopes. They High quality leads that they build for you. The prices are good too for the quality you get.
This is what you want- (https://www.aeswave.com/Automotive-Test-Lead-Kit-p9121.html)

Now onto the car. The ECM connectors have covers on them that can be removed for testing. Pins 19 and 20 look okay. Pin 66 is not good. With the key on you should have at least 0.4-0.5volts at closed throttle. "There's your problem" if you have the black lead correctly grounded. The code sets because of a voltage signal lower than 0.1v.
Pin 16 Connector 1 is the ECM Ground pin. Again if you have the meter leads grounded correctly, that reading is ok, its reading -0.02 because the meter leads are reversed. The other way it would be reading 0.02, so that's okay. Pin 66 is our issue here,

Are you getting that same reading at the TPS itself on the dark blue wire?
If not there's a broken wire somewhere.
If you go to the TPS and get a reading around 0.4-0.6, somewhere around there. You'll need to follow that wire, start taking it out of the harness and follow it to each connector. Take each connector you find along the way apart and check it for corrosion or breaks.

You need to carefully examine that wire as far as you can.
Eventually you will trace it back to the firewall. Use a really good flashlight and inspect that thing up and down.
Check for the same reading your getting at the TPS, at each connector that wire goes through,
You're getting close now. From what you're telling me, the ECM is not receiving the TPS signal.

And to your questions, no you should not being seeing 12v on that Dark Blue signal wire at the ECM (Pin 66 Connector 2).

I don't think you're going to erase anything by disconnecting the ECM bulk connector. You just have to have the key off before you do it. I have never lost any ECM programming, ie- Fuel Mapping, Shift Points. from disconnecting an ECM connector.
But you wont have any power to ECM for testing if you do disconnect it, usually I only disconnect the ECM plug to remove that cover and plug it back in so I can back probe the connector for testing.

In Honda's service manuals, they have you disconnect the ECM connector to test circuits. So i would say no to that question.

(Updated)
Try this too please, Key Off
Unplug the TPS and back probe the dark blue wire,
Set your meter on Ohms (Resistance testing)
And touch the back probed dark blue wire with the red lead and black lead to battery negative and tell me what you get for an Ohms reading.
This is a short to Ground test.

Here's some extra guides just to help further your knowledge:

https://www.2carpros.com/articles/how-to-use-a-voltmeter

https://www.2carpros.com/articles/how-to-check-wiring

https://www.2carpros.com/articles/throttle-actuator-service

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Man o man GM lovees electrical tape.

Did you find anything yet? Did you try the resistance test to ground? I checked around for information on this.

Apparently the harness can rub threw on the A/C accumulator (which is the round looking can in series on one of the AC lines), and also around the area where the ECM is due to vibrations. So also check inside near the ECM as well. Anywhere the harness has a contact point with the frame or engine block.

You're absolutely certain you had no reading at all at the ECM on pin 66 with the key On? While having a reading at the sensor itself?
Just so we're clear that the Signal is not making it to the ECM from the TPS.

With you opening up the throttle and just getting the air rushing in noise, (which i have had before as well). Seems that the ECM doesn't know you're opening the throttle, therefore not adding any fuel.

The truck I had that was doing this had a bad ECM, the throttle plates would open with the cable from the pedal, air would rush in, but the ECM would not increase the injector pulse width, so no added fuel.
I'm still digging for more information as well.

Hey, I went back to the fire wall and couldn't see or feel anything, under the dash the ECM connector has a screw in the middle that is held in place by a washer. That keeps the parts from separating and I couldn't push it out. At any rate, I decided to redo some test starting from the beginning with back probing the TPS sensor connection on the wire side. grey/black read good 5.00 black read 0.01 blue read 0.01 and when I pressed on the throttle nothing happened at all. I tried different placement of pins, different pins and different grounds and the readings remained consistent. there wasn't movement.

back probing blu wire car running multimeter reading 1.60 - 1.62. If I press on throttle it topped out at 4.53 but was bouncing around a lot. 4.53 to maybe a 4.49 it was hard to get a good read and that was with my black wire on the battery negative.
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