P0121 TPS pending code and losing 12V low reference ground to ECM. lntermittent high ldle and late shift issue.

[mrbreezeet1]

Tech on another group had a pretty good hunch, based on the same information I started this thread with.

 

[mrbreezeet1]

How did you determine that you are missing the ground signal? Have you tested for pin tension at the connector at the TPS and ECM?

Not necessarily missing all together I knew it wasn't continuity and the Black clover reference wire I'm referring to, I just thought maybe it was like compromised intermittently.

 

[Rand]

When you start a thread like this is always best practice to include a link to other threads that are relevant if you had previous ones
and also the vehicle information.
Your location is also sometimes important to advice.

I thought maybe you had a 2018 truck with a rusted out ground strap without any other information available.....

 

[mrbreezeet1]

When you start a thread like this is always best practice to include a link to other threads that are relevant if you had previous ones
and also the vehicle information.
Your location is also sometimes important to advice.

I thought maybe you had a 2018 truck with a rusted out ground strap without any other information available.....

Sorry Brother I have a tendency to cause confusion these days I think. Thought it was everyone else, but found out it's me.

 

[mrbreezeet1]

How did you determine that you are missing the ground signal? Have you tested for pin tension at the connector at the TPS and ECM?

Awe! I made a detailed post late last night from my phone. Now it's not here! I'll try to compose it again, who knows maybe I forgot to send it. Honest to God, my mind anymore.

 

[mrbreezeet1]

Awe! I made a detailed post late last night from my phone. Now it's not here! I'll try to compose it again, who knows maybe I forgot to send it. Honest to God, my mind anymore.

Nope I can't find it nowhere on my phone or anywhere God knows what I did?

 

[mrbreezeet1]

When you start a thread like this is always best practice to include a link to other threads that are relevant if you had previous ones
and also the vehicle information.
Your location is also sometimes important to advice.

I thought maybe you had a 2018 truck with a rusted out ground strap without any other information available.....

First off, I'm in Bridgeport Ohio. (Across River From Wheeling WV)

 

[researcher]

Sorry Brother I have a tendency to cause confusion these days I think. Thought it was everyone else, but found out it's me.

hey @mrbreezeet1 at least I know what you're talking about!! Been following your other post.. about your 2001 Grand Prix with the TPS Check Engine Light, then it was causing odd shifting in the auto trans. I'll go look and see if I can find the other posts and list them here for ya.. Playing on the cell phone when trying to look stuff up isn't just you.. It's like looking at the world through a peep hole on a door! Instead of widescreen high def!! After dinner I'll see what I can find for ya..

 

[mrbreezeet1]

hey @mrbreezeet1 at least I know what you're talking about!! Been following your other post.. about your 2001 Grand Prix with the TPS Check Engine Light, then it was causing odd shifting in the auto trans. I'll go look and see if I can find the other posts and list them here for ya.. Playing on the cell phone when trying to look stuff up isn't just you.. It's like looking at the world through a peep hole on a door! Instead of widescreen high def!! After dinner I'll see what I can find for ya..

Thanks Brother!
I worked as a "general mechanic" most of my life, but never had a chance to stay up on the newer systems.
I understand them, and can fight them, and I usually win, but not doing them every day, it's not as easy as a current "Hi Tech tech" working on one of these systems. Well, that's one thing, but then schematics and Pin-Out charts being wrong makes it hard too, trying to test wiring, without the schematics and Pin-Out charts sending you to the wrong connector and wrong pin numbers!

 

[mrbreezeet1]

How did you determine that you are missing the ground signal? Have you tested for pin tension at the connector at the TPS and ECM?

Anyways I lost my long comment, one part of it is, a tech on another group was highly suspicious of the low reference wire "B at TPS to C 2 connector pin # 62"..... black wire, but it is OK. I ran a new wire, as it is not shared with any other sensors, but no Joy!
And now trying to run a few resistance tests. Hot motor bay vers. cold motor bay, I'm finding my schematics and my C 1 and C 2 connector pin call out charts WRONG!
ECM C1 and C2 pins look clean, no corrosion I can see, gonna hit them with some cleaner and protector anyways.
Already replaced the 3 wire connector to the TPS as far as the new wire on it would allow. Did good visual inspection and wiggle tests everywhere l could see.

 

[researcher]

Thanks Brother!
I worked as a "general mechanic" most of my life, but never had a chance to stay up on the newer systems.
I understand them, and can fight them, and I usually win, but not doing them every day, it's not as easy as a current "Hi Tech tech" working on one of these systems. Well, that's one thing, but then schematics and Pin-Out charts being wrong makes it hard too, trying to test wiring, without the schematics and Pin-Out charts sending you to the wrong connector and wrong pin numbers!

oh yeah, you think the info is correct but then it was for the mid-cycle refresh of your car, not your model year! stuff like that.. doesn't really help to solve the problem only adding frustration!

ok.. I didn't get to this until now (long day, fell asleep early last night).. here's another of your posts about this

When lt rains it does pour too

1st the high ldle late shift TPS P0121 issue, now new racket under hood. Does this sound like the tensioner pulley or "hard to say, have to pull the belt and check"

bobistheoilguy.com

the following link was about the MAF sensor and you posted about that, then it turned into finding the TPS sensor issue. Since it was on another member's thread you opened up a new thread. It's starting at post #40

Are there any good aftermarket MAF sensors?

SMP (standard motor products) would be a reliable aftermarket choice. I don't know if they make anything, make some things, re-brand others or what.... But I've bought a vent purge valve for our Civic and a vent solenoid for my G35, both SMP boxed, and both were made in Japan. I'd like to think...

bobistheoilguy.com

The original looks like oct 5 2023..

2001 Grand Prix SE High Idle and late shifting too! {Must have taken a fit, It's OK now}

2001 Grand Prix SE with 3.1-liter motor. After I started my Grand Prix when cold, and drove it about 30 miles, and came home, it started idling high, around 1500. After it started idling high it started shifting noticeably late. If I shut the engine off and immediately restart it, it started...

bobistheoilguy.com

I think that's all of them.. that way you can have them all referenced, no problem brother! you're most welcome.

 

[mrbreezeet1]

C 1 is the top connector and C 2 is the Bottom connector. What mixed me up was according to the schematic was it looked like Terminal B from the TPS to Pin 61 at the ECM was on C2 but it's really on C 1.
So then I sort of jumped the gun and said, OK the top connecter is C 2.
So that mixed me up trying to do my resistance tests on the wiring.

 

[researcher]

C 1 is the top connector and C 2 is the Bottom connector. What mixed me up was according to the schematic was it looked like Terminal B from the TPS to Pin 61 at the ECM was on C2 but it's really on C 1.
So then I sort of jumped the gun and said, OK the top connecter is C 2.
So that mixed me up trying to do my resistance tests on the wiring.View attachment 185212View attachment 185213View attachment 185215

ahh I see what you're saying, that faint dotted line between the PCM and the connector showing C1 on the right, almost could miss that.. But sounds like you've got it sorted out now.. be interesting to see what testing shows..

 

[mrbreezeet1]

Oh yeah! Well, I didn't know. I guess that's what that means. They should just write C 1 beside it like I did.
That's what that is I would say then. I need to study how to read a schematic if I have to do this again.

 

[mrbreezeet1]

Rather than try to find a possible intermittent open or short or high resistance, I'm tired of fooling around with this,
I'm just going to run all 3 wires new from the TPS to the ECM.
One at a time though. I've done A & B so far. Have to do the signal wire C next. Also, my dongle for my Torque Pro app must be bad, I can't connect right now. Noticed my vacuum went low the other day at Idle, that is next when I get my Dongle here. Figured I just do the wiring now, and just road test it between wire replacement.
If wiring and possibly vacuum leak and testing the MAF sensor don't fix it, IDK looks like possible ECM.
Don't know what else to do.

 

[zzyzzx]

I'm adding this thread to my list of proof that TPS sensor affects the transmission.

 

[researcher]

Rather than try to find a possible intermittent open or short or high resistance, I'm tired of fooling around with this,
I'm just going to run all 3 wires new from the TPS to the ECM.
One at a time though. I've done A & B so far. Have to do the signal wire C next. Also, my dongle for my Torque Pro app must be bad, I can't connect right now. Noticed my vacuum went low the other day at Idle, that is next when I get my Dongle here. Figured I just do the wiring now, and just road test it between wire replacement.
If wiring and possibly vacuum leak and testing the MAF sensor don't fix it, IDK looks like possible ECM.
Don't know what else to do.

I think you're on the right track.. wire up the 3rd wire and then see what the results are. If the Torque Pro cannot connect to the OBD2 then try another vehicle. If the ECU/ECM is bad then things like the OBD2 port not working can happen. If it doesn't work in another vehicle then you know it's the Torque Pro, not the ECU.

About the idle.. I agree, get the wiring part finished first then see where you are. I know it's frustrating, electrical troubleshooting is one thing people moan about, since it's time consuming and needs patience.. You're getting there!

 

[mrbreezeet1]

I'm adding this thread to my list of proof that TPS sensor affects the transmission.

You better believe it Smudge, er..........A......... I meant ZZYZZX
As stated............................ That was the symptom that 1st. alerted me that something was a-miss.

 

[mrbreezeet1]

I think you're on the right track.. wire up the 3rd wire and then see what the results are. If the Torque Pro cannot connect to the OBD2 then try another vehicle. If the ECU/ECM is bad then things like the OBD2 port not working can happen. If it doesn't work in another vehicle then you know it's the Torque Pro, not the ECU.
About the idle.. I agree, get the wiring part finished first then see where you are. I know it's frustrating, electrical troubleshooting is one thing people moan about, since it's time consuming and needs patience.. You're getting there!

Oh, cool! I did not know that about the ECM not allowing communication.
I only have the one car, but I guess I can "borrow" a neighbor's car.

If the ECU/ECM is bad then things like the OBD2 port not working can happen. If it doesn't work in another vehicle then you know it's the Torque Pro, not the ECU.

Thanks Brother!

 

[mrbreezeet1]

EDITED: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^