2G TPS Reading 100% Plugged in???

95_gsx_tuner · Oct 30, 2008

After many hours of reading and trying this is what i've come up with. The problem came from no where and my car wouldn't start. I noticed on the AFC that my throttle was at 100%. So i went to WOT and there was no change. I went into the AFC ETC. and checked the TPS voltage and it was right at 5.0 volts with the throttle closed. So I unplugged the TPS and voltage read .01, and the car started. When I plug the TPS back in it shut right off. I tried cleaning the connectors, swapping with a known good TPS, checking the wiring of the AFC, and pulling the negative terminal off in chance of resetting the PCM. I've had to car for over a year with the AFC hooked up and never had a problem. Sorry for the essay but i'm stumped on this one.

VancTalonAWD · Oct 30, 2008

TPS voltage at idle should be around 1V and WOT should be close to 5V. Did you check the sensor type is set correctly in the AFC? Make sure the arrow is pointing in the upward direction otherwise the AFC will read the sensor backwards.

Could also be a problem with the AFC. If you know someone with an AFC maybe swap in theirs and see if it fixes the problem.

95_gsx_tuner · Oct 30, 2008

AFC is properly setup with Karman sensor type and 4cyc and an up arrow, i tried another AFC and it does the same thing, I kno the PCM couldn't have fried bc it will still start and run with the TPS unplugged, I was wondering if the MFI relay had anything to do with it???

adidas_coin · Oct 30, 2008

Backprobe your TPS with a voltmeter, check for the 1v min and 5v max and a few in between if you want, and on a side note most sensors operate on 5v so if the wrong one was tapped this could happen.

95_gsx_tuner · Oct 31, 2008

I've got the correct wiring for the AFC, its been hooked up for over a year with no problems, but the TPS reads 5v all the time regardless if it is closed or WOT. I tried re-wiring the AFC and no change. The only thing that i've done recently is wire an rear O2 sensor up and but had to wrong wiring so i un did it. I also noticed that when i run the car with the TPS unplugged that both fans constantly run and when i unplug the MAP or MAS there is no change in idle. Also, the positive terminal burnt the f**k out of my hand, so its leading me towards a short but i've checked all the wiring under the hood and under the dash and there is no signs of damage. I'm really stumped on this one???

adidas_coin · Oct 31, 2008

lets take it one at a time

5V all the time....is that acording to your AFC or the sensor itself? (the fans with the TPS unplugged is a safety feature if im not mistaken)

As for the battery terminal does it only do that running? if not do a parasitic drain test while its parked and off

95_gsx_tuner · Oct 31, 2008

5v all the time according to volt meter, and yes the terminal only got hot when running, its fine when the key is on and not running

adidas_coin · Oct 31, 2008

95_gsx_tuner said:
5v all the time according to volt meter, and yes the terminal only got hot when running, its fine when the key is on and not running

sounds like a ground issue to me.

95_gsx_tuner · Oct 31, 2008

i'll try that bc i'm stumped but what would you suggest???

adidas_coin · Oct 31, 2008

you said there was a build right? you need to check your wiring (ESPECIALLY) your heavy cables. starter, alternator. and all chassis to block/head grounds. also the ground to your tps. and if you get really desperate do a continuity test from the ecu pin to the TPS. with your POS batt. cable getting that hot im suprised that TPS is the only issue you're having. well its past my bedtime, keep the thread updated with your progress.

95_gsx_tuner · Oct 31, 2008

no there was no build, the car has had this setup since i've owned it, but i'll recheck all the grounds and let ya know what i find thanks

RyanEricW · Oct 31, 2008

If it's not a ground, check the resistance within the TPS it-self. Put one lead on the 5V Ref terminal and the other on the signal terminal. (With the plug connector unplugged of course).

With the throttle plate closed (idle position), it should read a pretty good amount of resistance.
With the throttle plate open (WOT), it should read close to 0 ohms. (Not saying it's going to be 0, but close).

If both readings are low ohms, then you have a short between the reference wire and signal wire, causing you to get WOT voltage as if there was no resistance in that potentiometer. Very rare in TPS's.

Anyhow I hope that helps.

adidas_coin · Oct 31, 2008

the ground was more about the hot pos terminal then the tps

95_gsx_tuner · Nov 3, 2008

well i checked the grounds and they were all connected and i looked the wires over and they were all good as well, i was reading about the o2 wiring and how its grounded through the PCM and that so is the TPS, MASS, and MAP. I'm thinking that i fried the computer, any input???

rEclipserGST · May 17, 2009

95_gsx_tuner said:
well i checked the grounds and they were all connected and i looked the wires over and they were all good as well, i was reading about the o2 wiring and how its grounded through the PCM and that so is the TPS, MASS, and MAP. I'm thinking that i fried the computer, any input???

Is the car Bogging or not Down Shifting when depressing the throttle all the way to the floor? My SAFC reads 100% as well, and the car will not down-shift. It will only down-shift with the lever (ie its an Automatic). Maybe the TPS itself is shot. I replaced mine not to long ago with a used one. But it seems as though it could be bad still. LET ME KNOW if You are having Performance issues as well. Thanks

talon14turbo · Jun 26, 2009

95_gsx_tuner said:
After many hours of reading and trying this is what i've come up with. The problem came from no where and my car wouldn't start. I noticed on the AFC that my throttle was at 100%. So i went to WOT and there was no change. I went into the AFC ETC. and checked the TPS voltage and it was right at 5.0 volts with the throttle closed. So I unplugged the TPS and voltage read .01, and the car started. When I plug the TPS back in it shut right off. I tried cleaning the connectors, swapping with a known good TPS, checking the wiring of the AFC, and pulling the negative terminal off in chance of resetting the PCM. I've had to car for over a year with the AFC hooked up and never had a problem. Sorry for the essay but i'm stumped on this one.

What did you find out? I have the exact same problem. It just happened today. The car was running fine and shut off all of a sudden. Tried to start it and it would not stay started and is running very rich. I then noticed that the tps on afc read 100%. If I disconnect the tps, it reads 0% but I have to hold my foot on the gas but it would run much better. I'm stumped so can anyone help out on this one?

And I forgot to add that I changed the MAS because I noticed that the 2 middle wires were burnt (the black wire & red wire). After changing to a new mas, I still had the same problem.

Bluesideup · Jun 26, 2009

Did you recently replace the TPS? I found my car would run extremely rich and run the radiator fan all the time. Problem turned out to be that someone replaced the TPS with the wrong part, all of the connections were backwards. Yours should read - O S + from top to bottom when mounted on the throttle body.

talon14turbo · Jun 27, 2009

No I did not replace it. I only noticed it was reading 100% after the car killed. After attempting to start it, it would blow black smoke out the exhaust and run really rough.

talon14turbo · Jun 28, 2009

Quick Update. Steve, a member on here has some good info. I did a lot of searching and research. It was a blown sensor ground. I guess the bad maf caused the problem so I'm glad I purchased a new one.

Now can anyone can tell me where I can purchase the wire plug for the maf meter?

mitsuowner1991 · Sep 11, 2019

talon14turbo said:
Quick Update. Steve, a member on here has some good info. I did a lot of searching and research. It was a blown sensor ground. I guess the bad maf caused the problem so I'm glad I purchased a new one.

Now can anyone can tell me where I can purchase the wire plug for the maf meter?

Im having this same damn problem. Its at .5 on my afc but if i check it under the hood its reads 4.86closed and close to .3 WOT..

steve · Sep 12, 2019

talon14turbo said:
Quick Update. Steve, a member on here has some good info. I did a lot of searching and research. It was a blown sensor ground. I guess the bad maf caused the problem so I'm glad I purchased a new one.

Sure it wasn't something you did playing with the rear O2 sensor?

mitsuowner1991 · Sep 13, 2019

Ok so i figured out my problem.. while checking the volts on my TPS i couldnt figure out why i couldnt get lower then 4.03v on my meter.. well i wasnt grounding the meter to the chassis.. stupid mistake... my Tps is at .5 closed and 4.93 WOT..

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2G TPS Reading 100% Plugged in???

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