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TP1 sensor signal circuit is shorted to TP sensor signal 2 circuit means those two have somehow come together causing them to short out. Trace those two wires until you find where they've joined together because they should not be. It's either bad wires or bad component.
Same thing I said but this guy here won't do it.
Something so simple..
Originally Posted by Tma120
Sorry I didnt mean to insult anyone here, nor I thing that I am in expert in any of this. I am just a DIY guy looking for help and answers.
I am not an electrician, and do not have much knowledge about the subject, but I believe that I do understand a little bit of it. Now TP 1 and TP 2 are Potentiometer sensors...Again with my limited knowledge on this, I came up with my conclusion based by looking at the TPS and TAC circuit diagram i had posted in previous post, and this Potentiometer drawing below. Maybe with your expertise on the subject you will explain to us. Thanks for your input.
My post #24 in this thread says the same thing, you just don't want to listen, I've posted enough stuff to help you troubleshoot your problem.
There's two circuits there that are POTs, when they are plugged in and everything is connected.
You should be looking at the vehicle not here posting.
Last edited by the_merv; Jan 29, 2025 at 05:12 AM.
Same thing I said but this guy here won't do it.
Something so simple..
My post #24 in this thread says the same thing, you just don't want to listen, I've posted enough stuff to help you troubleshoot your problem.
There's two circuits there that are POTs, when they are plugged in and everything is connected.
You should be looking at the vehicle not here posting.
Okay Mr expert, please don’t get too much over yourself here, I appreciate the help but plz no need for all that.
Anyways, I replaced the TPS and haven’t seen that code again, yet, maybe that was the issue, will see.
would actually be great if you could tell us how many volts are on that TP 1 and TP 2 signal wire F and G before connecting the TPS pigtail, and explain to us why it’s reading what you see. That may be more helpful to us that don’t have much knowledge on the subject. Thanks.
You just became the expert on POT circuits there hero, why are you asking us here?
So elaborate.. I'm at work now and we want some entertainment.
You unplug the wiring from the Throttle Body, you have voltage in places you shouldn't with that wiring unplugged, and you replace parts in the Throttle Body that was completely unplugged.
Pretty sure I'm tracking right.
Last edited by the_merv; Jan 29, 2025 at 06:22 AM.
You just became the expert on POT circuits there hero, why are you asking us here?
So elaborate.. I'm at work now and we want some entertainment.
You unplug the wiring from the Throttle Body, you have voltage in places you shouldn't with that wiring unplugged, and you replace parts in the Throttle Body that was completely unplugged.
Pretty sure I'm tracking right.
Man, am not here to entertain, again am new to all this and learning as I go, no need to try to be smart here, I say that with all respect. If my little knowledge on the subject bothers this much then please move on. No need to waste time here.
Thanks again for all your input. Blessed!
When I was new to cars I listened to what people told me if I couldn't figure it out on my own. They told me what they did for a reason. That's how I learned.
Couple of us are telling you why you have the code you have, telling you to check the wiring, and you're over there throwing parts at it. Stuff literally tells you with codes now, some of us had to figure out cars with nothing to start with but the problem. That's how you really learned.
Not my money not my problem. This advice is free here, a shop would charge you for it. Free advice isn't good enough apparently.
When I was new to cars I listened to what people told me if I couldn't figure it out on my own. They told me what they did for a reason. That's how I learned.
Couple of us are telling you why you have the code you have, telling you to check the wiring, and you're over there throwing parts at it. Stuff literally tells you with codes now, some of us had to figure out cars with nothing to start with but the problem. That's how you really learned.
Not my money not my problem. This advice is free here, a shop would charge you for it. Free advice isn't good enough apparently.
Going through the wiring as advised above is the first thing I did, couldn't find a bad wire, now did I do it right, ? It's not like am here saying you guys are wrong, no, none of that, just that I cant find the issue with the wiring.
The TPS didn't cost me anything, I threw it on because I had it laying around. I do learn alot reading these posts, and I truly do appreciate every second you guys put into coming on here to help out.
The TPS, TAC, APP system as illustrated below is a complex system to me, and maybe I am lacking the proper knowledge to troubleshoot the issue, but I did go through the 8 wiring between the TAC and the TPS as suggested in previous post and couldn't find the issue.
Thanks again for everyone time put into helping out here. Much appreciated.
You went through the wiring eh? Well thanks for letting us know, now..
So, all 8 wires are completely fine nothing bare, touching, crushed, etc? That whole 8 wire segment from the Throttle Body to the TAC Module is perfect all the way through?
With this stuff it gets to the point you have to strip the harness down to 100% wire only and trace each one. That's just how it goes.
Yup, that diagram is the whole system, schematics are good to have so save it.
would actually be great if you could tell us how many volts are on that TP 1 and TP 2 signal wire F and G before connecting the TPS pigtail, and explain to us why it’s reading what you see. That may be more helpful to us that don’t have much knowledge on the subject. Thanks.
You found the diagrams below and they are correct so I'll explain it.
The Potentiometer, or POT.
1 - Voltage in
2 - Resistance Signal out
3 - Ground
On the diagrams with the above:
1 - H, E
2 - G, F
3 - D, B
Troubleshooting this with that Throttle Body Connector unplugged you should have this:
H, E - 5v
B, D - this is the ground so check continuity to the Neg Battery Terminal. The TAC Module grounds this circuit internally.
G, F - this is the TP Signal back to the TAC Module. Them two POTs are in the TP Sensor in the Throttle Body. Will be nothing on these wires unplugged.
So when you have it unplugged and have anything close to 5v on B, D and/or G, F, there's a problem somewhere.
That's why you're getting the short code.
If the wiring is 100% fine end to end with the Throttle Body unplugged, the next step is to make sure the TAC Module is properly powered and grounded. If it is, then try another Module, something internally in it could be fried on the board.
You found the diagrams below and they are correct so I'll explain it.
The Potentiometer, or POT.
1 - Voltage in
2 - Resistance Signal out
3 - Ground
On the diagrams with the above:
1 - H, E
2 - G, F
3 - D, B
Troubleshooting this with that Throttle Body Connector unplugged you should have this:
H, E - 5v
B, D - this is the ground so check continuity to the Neg Battery Terminal. The TAC Module grounds this circuit internally.
G, F - this is the TP Signal back to the TAC Module. Them two POTs are in the TP Sensor in the Throttle Body. Will be nothing on these wires unplugged.
So when you have it unplugged and have anything close to 5v on B, D and/or G, F, there's a problem somewhere.
That's why you're getting the short code.
If the wiring is 100% fine end to end with the Throttle Body unplugged, the next step is to make sure the TAC Module is properly powered and grounded. If it is, then try another Module, something internally in it could be fried on the board.
I think that sums it up quite well.
Yeap, when unplugged, I am getting 5v on H, E, 0.5v on D, B, and 4.93v on G,F (Signal wires). I measure all these wires voltage with multi meter one end on the wire, the other on battery Neg
I will check continuity to the Neg Battery on B, D wires later.
Where do the TAC module gets the 12v power from? I see ground on pin 15.
The TPS goes to the TAC module, including of course terminals B and D which are called "Low Reference". Last time I worked on a TAC module, I measured that B and D are essentially grounds and should have close to 0 Ohms when measured to either the TAC case or the car's ground. A very experience GM mechanic told me to be sure the TAC module case had a good ground wire going to it.
The purpose for a "Low Reference" is to have a dedicated ground wire going directly to electronic signal measuring circuit to ensure accuracy; e.g. to ensure that turning on lights or the radiator fan doesn't send it heavy current through the "low reference" as it does with general ground wires. However, internally in the TAC, the Low Refence then connects to ground.
My suggestion is to check the continuity (Ohms) between B/D and the case of the TAC module, and then between the case of the TAC module and battery/chassis ground.
From there it might be obvious what the problem is, or we can likely help you further.
You found the diagrams below and they are correct so I'll explain it.
The Potentiometer, or POT.
1 - Voltage in
2 - Resistance Signal out
3 - Ground
On the diagrams with the above:
1 - H, E
2 - G, F
3 - D, B
Troubleshooting this with that Throttle Body Connector unplugged you should have this:
H, E - 5v
B, D - this is the ground so check continuity to the Neg Battery Terminal. The TAC Module grounds this circuit internally.
G, F - this is the TP Signal back to the TAC Module. Them two POTs are in the TP Sensor in the Throttle Body. Will be nothing on these wires unplugged.
So when you have it unplugged and have anything close to 5v on B, D and/or G, F, there's a problem somewhere.
That's why you're getting the short code.
If the wiring is 100% fine end to end with the Throttle Body unplugged, the next step is to make sure the TAC Module is properly powered and grounded. If it is, then try another Module, something internally in it could be fried on the board.
I think that sums it up quite well.
just being pedantic here in case someone reads the thread in the future -
if you believe the schematic, it looks like pin G on the TAC module has an internal pull down resistor to ground, so you should definitely see 0 volts on pin G if nothing is plugged into the tac module.
However it looks like pin F has an internal pull up resistor, so you will see voltage on pin F. The internal pullup is probably to 5V rather than 12V. So you will likely see 5V on pin F if nothing is plugged in to the tac module and the tac module is powered on.
The TPS goes to the TAC module, including of course terminals B and D which are called "Low Reference". Last time I worked on a TAC module, I measured that B and D are essentially grounds and should have close to 0 Ohms when measured to either the TAC case or the car's ground. A very experience GM mechanic told me to be sure the TAC module case had a good ground wire going to it.
The purpose for a "Low Reference" is to have a dedicated ground wire going directly to electronic signal measuring circuit to ensure accuracy; e.g. to ensure that turning on lights or the radiator fan doesn't send it heavy current through the "low reference" as it does with general ground wires. However, internally in the TAC, the Low Refence then connects to ground.
My suggestion is to check the continuity (Ohms) between B/D and the case of the TAC module, and then between the case of the TAC module and battery/chassis ground.
From there it might be obvious what the problem is, or we can likely help you further.
Ok thanks. The above image i posted shows the continuity reading between B/D and battery negative. I will check against the TAC case. Should that case be bolted to the body?
just being pedantic here in case someone reads the thread in the future -
if you believe the schematic, it looks like pin G on the TAC module has an internal pull down resistor to ground, so you should definitely see 0 volts on pin G if nothing is plugged into the tac module.
However it looks like pin F has an internal pull up resistor, so you will see voltage on pin F. The internal pullup is probably to 5V rather than 12V. So you will likely see 5V on pin F if nothing is plugged in to the tac module and the tac module is powered on.
ah! That may explain the 4.93v on pin F when unplugged, but pin G was also reporting 4.93v last time I checked.
just being pedantic here in case someone reads the thread in the future -
if you believe the schematic, it looks like pin G on the TAC module has an internal pull down resistor to ground, so you should definitely see 0 volts on pin G if nothing is plugged into the tac module.
However it looks like pin F has an internal pull up resistor, so you will see voltage on pin F. The internal pullup is probably to 5V rather than 12V. So you will likely see 5V on pin F if nothing is plugged in to the tac module and the tac module is powered on.
That is absolutely correct, I didn't catch that on my cellphone earlier. I see it clear as day on my computer screen.
Originally Posted by Tma120
ah! That may explain the 4.93v on pin F when unplugged, but pin G was also reporting 4.93v last time I checked.
If Pin G has that voltage on it, that is why you are seeing this here...
If the wiring is 100% fine then it's something internal in the TAC Module. Checking grounds as mentioned above won't hurt, that high resistance reading you got tells me something is touching that shouldn't be. Can mount the TAC anywhere just needed it grounded well. It's on the Firewall in the trucks usually, next time I look at one I'll see if it has a case ground.
Rechecked the voltage and reading 4.93v on pins G/F
Continuity reads:
B/D to TAC case (case is aluminum) = OL
B/D to Chassie ground = 16 ohms
B/D to Battery Neg = 69 ohms
All the above readings are with the Key on engine Off.
Important: I also notice that when checking continuity between Battery Neg and grounds points (body, engine block etc) it reading about 16 ohm with the Key On, BUT with Key Off, I get almost perfect connections showing 00 ohms between the same points.
Rechecked the voltage and reading 4.93v on pins G/F
Continuity reads:
B/D to TAC case (case is aluminum) = OL
B/D to Chassie ground = 16 ohms
B/D to Battery Neg = 69 ohms
All the above readings are with the Key on engine Off.
Important: I also notice that when checking continuity between Battery Neg and grounds points (body, engine block etc) it reading about 16 ohm with the Key On, BUT with Key Off, I get almost perfect connections showing 00 ohms between the same points.
definitely measure resistance with the key off. measure voltages with the key on.
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