# Where is the TPS?



## 4t7 (Sep 29, 2015)

I'm trying to locate the whereabouts of a TPS (throttle position sensor) on my van. The van is a 1995 Chevy G20 with a 350 in it. Where is this thing?

Also any tips/advice/wisdom about how to test if this thing is bad once I locate it would be greatly appreciated. Thanks!

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## SeniorSitizen (Sep 10, 2012)

4t7 said:


> I'm trying to locate the whereabouts of a TPS (throttle position sensor) on my van. The van is a 1995 Chevy G20 with a 350 in it. Where is this thing?
> 
> Also any tips/advice/wisdom about how to test if this thing is bad once I locate it would be greatly appreciated. Thanks!
> 
> Sent from my LGL34C using Tapatalk


I googled _*" 350 chevy tps " *_and the result was at least 4 videos. I didn't watch any but give it a try.


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## goobertime (Mar 19, 2016)

4t7 said:


> I'm trying to locate the whereabouts of a TPS (throttle position sensor) on my van. The van is a 1995 Chevy G20 with a 350 in it. Where is this thing?
> 
> Also any tips/advice/wisdom about how to test if this thing is bad once I locate it would be greatly appreciated. Thanks!
> 
> Sent from my LGL34C using Tapatalk


should be on the throttle body ontop of the manifold...I had an 88 chevy van with a throttle body...if you goto rock auto and look at the new part then you will know what to look for visually..


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## Brainbucket (Mar 30, 2015)

95 Chevy 350 should be a TBI (Throttle Body Injection) unit with the TPS on the pass side of throttle body on the throttle shaft opposite of the throttle cable. You test the TPS with a sweep test. Ya git the broom... na just joking. Either a scanner set on the TPS voltage and with key on, *engine off*, (KOEO) and go from idle to full throttle slowly or with a volt meter set to 10 volts. Max volts of the TPS is 5 volts. You go from idle to full throttle, that's a sweep test. TPS at idle should be 0.85 volts or less. Full throttle should be 5.00 volts (4.75 on up is ok.) You should have 3 wires at the TPS connector. Black (ground) Gray (5 volt reference) and Dark Blue (TPS signal). You make sure gray wire has 5 volts with KOEO. Put volt meter on Dark Blue and black wire and press down on throttle until it stops. Voltage will go from 0.85 volts to 4.98 volts steadily going up. Then let throttle go back to idle slowly and watch readings. If it jumps or goes to 0 or doesn't go up and down smoothly, it's bad. If you don't have a 5 volt reference, check wire to PCM. Check black wire for a good ground. If this checks out, Bad PCM. (Powertrain Control Module) But more than likely it's a bad TPS.:vs_cool:


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## 4t7 (Sep 29, 2015)

goobertime said:


> should be on the throttle body ontop of the manifold...I had an 88 chevy van with a throttle body...if you goto rock auto and look at the new part then you will know what to look for visually..


Thanks and good idea!


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## 4t7 (Sep 29, 2015)

Brainbucket said:


> 95 Chevy 350 should be a TBI (Throttle Body Injection) unit with the TPS on the pass side of throttle body on the throttle shaft opposite of the throttle cable. You test the TPS with a sweep test. Ya git the broom... na just joking. Either a scanner set on the TPS voltage and with key on, *engine off*, (KOEO) and go from idle to full throttle slowly or with a volt meter set to 10 volts. Max volts of the TPS is 5 volts. You go from idle to full throttle, that's a sweep test. TPS at idle should be 0.85 volts or less. Full throttle should be 5.00 volts (4.75 on up is ok.) You should have 3 wires at the TPS connector. Black (ground) Gray (5 volt reference) and Dark Blue (TPS signal). You make sure gray wire has 5 volts with KOEO. Put volt meter on Dark Blue and black wire and press down on throttle until it stops. Voltage will go from 0.85 volts to 4.98 volts steadily going up. Then let throttle go back to idle slowly and watch readings. If it jumps or goes to 0 or doesn't go up and down smoothly, it's bad. If you don't have a 5 volt reference, check wire to PCM. Check black wire for a good ground. If this checks out, Bad PCM. (Powertrain Control Module) But more than likely it's a bad TPS.:vs_cool:


Seriously, thanks for this detailed reply first and foremost. I have a couple questions still though...

First what is pass side of the throttle body? Is that gonna be on the right side?

I think once I find this sensor I understand how to correctly test it, but another question about that...When I'm testing the wires to the sensor do I just stab into the wire with my voltometer prod?

I don't understand that last part about testing the PCM wire..? And yeah I'm really hoping it is just a bad TPS.

Anyways thanks again! Reallly appreciate the help.


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## Brainbucket (Mar 30, 2015)

Setting in the drivers seat, left is drivers side. Right is passenger side. Back probe wires ie, stick test lead into the back side of connector while it is plugged in TPS along the wire so you will contact the back side of the terminal key on, engine off.


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## 4t7 (Sep 29, 2015)

Brainbucket said:


> Setting in the drivers seat, left is drivers side. Right is passenger side. Back probe wires ie, stick test lead into the back side of connector while it is plugged in TPS along the wire so you will contact the back side of the terminal key on, engine off.


Hey, so I'm sitting here testing this TPS. My voltometer is reading it at 0.627 v base reading. And with WOT I'm at 4.47 v. So these readings seem a little low...What do you think @Brainbucket? Is this probably a bad sensor or am I ok? Also when opening throttle the volts do increase and decrease smoothly, NOT erratically.

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## Brainbucket (Mar 30, 2015)

What made you think TPS? Do you have a code? What problem do you have? Those readings are ok. The high reading, was it done with someone in the car and they were pressing on accelerator peddle or manually at the throttle body? If not manually, then look at floor mat or something not letting the peddle go all the way down.:vs_cool:


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## ZZZZZ (Oct 1, 2014)

Ahhh TPS.






Sorry for the diversion. Carry on.


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## 4t7 (Sep 29, 2015)

Brainbucket said:


> What made you think TPS? Do you have a code? What problem do you have? Those readings are ok. The high reading, was it done with someone in the car and they were pressing on accelerator peddle or manually at the throttle body? If not manually, then look at floor mat or something not letting the peddle go all the way down.:vs_cool:


I suspect/ed TPS because my van feels like it wants to go but it hesitates and kinda stumbles when trying to accelerate. Idk if there's any codes. It's obd1 and I'm waiting for an adapter that I ordered that will plug into it.

I did it at the throttle body manually and by pressing the gas pedal as well. I did both readings by myself and they were identical. There's is no floor mat or anything in the way of the gas pedal or throttle cable...I've already replaced spark plugs, and air filter. Found a cracked vacuum hose that I'm gonna replace on monday. Plan on checking/testing/cleaning: IAC, fuel injectors, catalytic converter, O2 sensor/s etc.

Any and all comments/ideas/advice/suggestions are greatly appreciated.


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## 4t7 (Sep 29, 2015)

ZZZZZ said:


> Ahhh TPS.
> 
> https://www.youtube.com/watch?v=Fy3rjQGc6lA
> 
> Sorry for the diversion. Carry on.


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## Brainbucket (Mar 30, 2015)

Check fuel pressure. I believe the specs are around 9-13 lbs. 9 is low. I like 12 or above. Check to see if you can blow through fuel filter easily. If fuel pressure is low, disconnect low pressure line next to fuel filter and no fuel should be coming out as fuel pressure regulator max relief pressure of 13lbs has not been reached. If so, bad regulator.:vs_cool:


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## 4t7 (Sep 29, 2015)

Brainbucket said:


> Check fuel pressure. I believe the specs are around 9-13 lbs. 9 is low. I like 12 or above. Check to see if you can blow through fuel filter easily. If fuel pressure is low, disconnect low pressure line next to fuel filter and no fuel should be coming out as fuel pressure regulator max relief pressure of 13lbs has not been reached. If so, bad regulator.:vs_cool:


Alright, good idea. Will I need some special tool to check fuel pressure..? Definitely gonna check this out (after I figure out where fuel filter, low pressure line, and regulator are located that is ) Thanks again for the help @Brainbucket.


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## Brainbucket (Mar 30, 2015)

Check it at the fuel filter location which is behind the drivers door under van inside frame rail. I have seen it above the right rear axle on a van. Return line (low pressure) fitting is right next to fuel filter. Remove fuel filter and blow. If it's hard to blow through, replace and drive it to see if it made a difference. If so, your good. If not, check fuel pressure. :vs_cool:


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## 4t7 (Sep 29, 2015)

Brainbucket said:


> Check it at the fuel filter location which is behind the drivers door under van inside frame rail. I have seen it above the right rear axle on a van. Return line (low pressure) fitting is right next to fuel filter. Remove fuel filter and blow. If it's hard to blow through, replace and drive it to see if it made a difference. If so, your good. If not, check fuel pressure. :vs_cool:


Man, you really know your stuff @Brainbucket. My filter was above the right rear axle. The filter didn't seem too terribly bad but I still went ahead and replaced it anyways. I also replaced two really cracked/leaky vacuum hoses. The problem still persists and actually seems a little worse now (gotta double check if I got that filter in right. Knowing me it's probably in backwards or something ) 

Van still just feels really rough and wants to die out on acceleration. Feels weak/no power. I actually rented one of those fuel pressure testers from the autostore but have yet to figure out how to use it (good thing there's no time limit on how long I can keep it, hah) But once I figure that out I'll check fuel pressure. 

All advice is definitely welcomed and appreciated!


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