How to test a Throttle Position Sensor TPS

Throttle position sensors are one of the common causes of surging, stalling and poor engine running. They are susceptible to water ingress which causes corrosion which in turn effects the resistance of the sensor at certain angular positions. This in turn effects the output voltage signal sent to the ECU.
As a result the ECU 'thinks' that the actual position of the throttle valve is more or less than it really is (usually more), it then basis its fueling calculations on the 'wrong' throttle position ultimately leading to excessive (or insufficient sometimes) fueling.
Knowing the correct way how to testing a TPS is very important, checking throttle closed output voltage, throttle wide open voltage and the progressive change in voltage as the throttle is opened and closed slowly.
Any minor 'glitch' in the voltage output, be it a spike (higher) or dip (lower) voltage can indicate a problem with the internal track.
If any of these specifications are suspect then the unit must be replaced. This video covers testing a TPS unit with both a digital volt meter (multi-meter) and an oscilloscope.
If you have any questions or comments please leave them in the comments section below...
Andy Mechanic!

[@benjaminhippolyte6681]

Andy I've been having issues with my TPS for 2yrs now and watching your video made such a HUGE difference, thank you so much ...🤙🤙🤙🤙🙌🙌🙌👍👍

[@AndyMechanic]

No problem Benjamin, pleased you found the video helpful. Thanks for your feedback. All the best. Andy

[@charlesmiller5078]

Kinda like problems we have with the old type AFM, good thing with those is we can adjust the tract board, and you get a whole new tract on the board, a little cleaner, and your good to go. I can see why your a teacher. Easy to follow.....

[@chandrakantindapurkar8738]

Thanks for adding such valuable information on TPS to my throtal knowledge.it is really interesting video. Thanking you.

[@donovanlucibello379]

Cheers from the States for posting this!

[@user-ks4kj3cv9h]

Nice work Andy informative and straight to the point, i appreciate your videos Cheers Dave Sinclair

[@garygarnett6469]

Loved the rain 🌧 in the back ground 😂😂

[@randypullman1155]

The schematic was like bonus footage. Bravo! Good work old boy.

[@sjbrocan1]

Andy, I am trying to troubleshoot my 2008 Yamaha Ourtboard. When I throttle the engine up and get to about 50% on the throttle lever the engine tops out. Basically I am only getting 50-60% power out of it. Is the TPS a likely culprit considering the symptoms? Thanks for your video and any feedback.

[@anaji5723]

Thank you. On my sonata 2000 the TPS will not decreases to under 2.3 volts with throttle fully closed. But when removed it working well .Although the idling adjusting screw is zero tension. Do you think I should re adjust the pinon of throttle when fully closed by loosen something to put the TPS to zero position?

[@Smalltechguy]

Very interesting Andy, I just purchased a new carb for my 2007 Honda 500 Foreman and the TPS is in the wrong position. The electrical connector will not real from the harness. The old carb had the TPS facing up. Do you have a video on how to move them around to fit...thanks

[@elneneeserio]

Andy thanks 4 the video ....My 04 subie workshop manual says to set it wile idle (throttle resting position) 0.6 v but it does not specify how to test it should it go higher, lower and or whats the minimum or max ? Would you know

[@ellefields8878]

It’s pretty easy to test the TPS, just take all weekend to compile and print a report.

[@Lambros_Stefaneas]

I have a question, what's the reason to exist the number 3 pin, which is the earth?I understand only two pins, 5volt reference, and the output signal, but what's the reason to exist the earth in the 3pin tps sensor?

[@raywatson5617]

Excellent!!

[@naui1980]

II have a 2004 Suzuki bandit I've tried testing the TPS sensor with my multimeter on the 2 outer most pins on either end... Saw your video on testing it and I saw you're running a 5 V lead do I have to do that with my 3 pin TPM S sensor off the bandit ??

[@simonparsloe7431]

great video i have a xj600n yamaha 99 plate which will only run on choke even when the engine is warm and if you apply the throttle it dies any ideas on what to do?

[@davidswezene1102]

A complete Carb cleaning might be the first choice here. Assuming this is an older carbureted model and not the newer injector system. Old gas that sits in the tank & fuel system for 6 months or more, can really gum up the fuel delivery system. This is especially true when 10-15% "Ethanol"is blended into gasoline. Common problem, easy fix sometimes. Most times, 1. Remove carburetor 2. A good cleaning of the exterior recommended 3. Inspect fuel bowl, jets and all orifices. They need to be cleaned of any obstructions, gunk or schmoo. Carb cleaner or Throttle Body cleaner should work in all but worst cases. Use compressed air after soaking carb & parts 4. Reassemble carburetor in the reverse order taken apart. 5.Specifications and settings for needle valves and float would be worth looking up for this engine. Google/KZbin will likely have videos on this subject if you look. If you find any damaged parts, now you're chasing for those as well. Good luck and hope it goes very well for you. Take your time and do it right the first time.

[@onecrookedeye1896]

learned a lot, natural born teacher!

[@haooto1260]

very good

[@fletcherbartling4756]

Hey what brand of power supply is that.

[@fid1987]

Got a tps on CV40 carb 1.0 at closed up to 5.8 when open. Spec says .5 at closed max wot 3.7 think this would cause no idel ??

[@AndyMechanic]

5.8 is impossible as its over the 5v reference. I think you may have a faulty multimeter?

[@fid1987]

Andy Mechanic Roger. Thanks!

[@davebarber3827]

Raise it to 0.45 or near, and less than 5.00 max 4. Or just over is fine.

[@chiaime-kq8nz]

Please do you have the specs of the TPS sensor, I really need the specs of all engine sensors.

[@Dagwood484]

Hello Will this make the motor not to idol at all, an hard to start..

[@cezarycezary4180]

Hey!!! I got 3 wires. Black/red, grey/yellow and grey white. Which one is ground and which one is the second one? Thanks!!

[@AndyMechanic]

I have no idea as the wire colours vary depending on make & model of vehicle. You can work it out though by using a multimeter. One wire will have the 5v reference, one will be ground & the remaining wire will be the signal wire back to the ECU. Cheers Andy

[@LifesAdventures555]

what brand oscilloscope are you using?? Thanks, very informative.

[@AndyMechanic]

I use a PicoScope 4 channel from Pico Technology. Cheers Andy

[@richardsmith9872]

Very funny! the last time I used an oscilloscope it took up an entire table... been a while I guess.

[@dtovee]

Thanks, I'm getting a c14 error on my Suzuki SV 1000 which is a TPS error so this has been helpful. I've got a good multimeter I've been thinking about getting an oscilloscope, yours looks really good but I guess expensive. I started in electrical/electronics over 30 years ago fixing circuit boards and move more into IT. I still can't believe IT guys in the workshop don't even have multimeters. Any suggestions for good workshop oscilloscopes? Thanks again :)

[@AndyMechanic]

no problem, we'll my first Picoscope only cost me $240 which I thought was very good. It wasn't a dedicated Automotive scope but still was very useful. Pleased you enjoyed the video. Cheers Andy

[@dtovee]

@@AndyMechanic I bought a TPS from ebay for my Suzuki, I'm going to try it out but it seems like it's a simple variable resistor (rheostat) with a spring with the far pins at opposite ends of the resistor track and the middle pin on the tracker. So I think you just use a multimeter measuring ohms to check the 'sensor'. It seems like a very expensive variable resistor! Thanks.

[@AndyMechanic]

The critical information you need are the specs. The resistance (or voltage output) when throttle is closed. this is very important info for the ECU. Without this spec (and it varies between models & manufacturers) you are shooting in the dark... Good Luck :-)

[@dtovee]

@@AndyMechanic Thanks, good point. If we knew the spec it would be easy to test. Thanks.

[@camlobesvtec]

Can a tps sometimes pass testing with the vehicle off or removed, but fail during engine operation? I have racing mounts that cause allot of vibration and I think this is happening to my tps.

[@AndyMechanic]

You need to test accurately, very slowly rotating to watch for any change in reading. Also check wires & pin connections too. :-)

[@camlobesvtec]

Everything passed. It's on a kseries honda where the tps are kinda known to fail with vibration. Sometimes the car performs well and other times it seems like its experiencing a lean mode, killing the power. A few times upon take off, it idled very low like it was about to miss but didn't. No engine light no backfiring. I'm stumped. Great videos brother thanks

[@AndyMechanic]

Ah, I had the same problem on a Chinese bike, passed all the usual testing yet when I swapped it out the lean issue & poor starting was fixed. Really odd but that part was also known to be damaged by vibration. This was a brand new bike out of a crate - the crate had been dropped! Cheers Andy

[@camlobesvtec]

Haha did the bike happen to be a honda cbr ? They use a similar tps as mine. Thanks bud I really appreciate it. Everything else seems to be in order and my final suspect is that tps.

[@tnamen1307]

What would happen if the iscv is disconnected when engine is running??? Will the engine stop or continue to run?

[@AndyMechanic]

Depending on the type of ISCV - if a steper motor type it will just stay at that position, ECU will then be unable to adjust RPM - if a 6 wire type then it will take a while for a fault code to flag. If there is a 7th wire - feedback to ECU - then fault code will flag quicker. What type of ISCV is it or what vehicle? Cheers Andy

[@tnamen1307]

Andy Mechanic it's hyundai i20 1.2 petrol manual transmission India version. It's 3 wire. When the iscv valve is disconnected during engine running, the engine instantly off. Is this normal??? However, the car can still be started with the iscv plug remaining disconnected!!!! Actually, i was trying to fix the car rpm which drops to 600 as against the normal 800 to 850 rpm at idle. Done throttle body cleaned, no warning signs, battery relearning process, etc etc but still low rpm!!!! No poor performance on engine while on road running. Everything is ok except the low rpm!!!! Also, I scanned with OBD scanner and the throttle position reads 5 or percent at idle . Is this normal range reading??? Doesn't the throttle valve is supposed to closed fully when idle ie it should show 0 percent???

[@edgarm865]

I have a WJ. Is a throttle closed voltage okay at 1.2v? Or is it too high? At fully open it is at 5.2 volts 🤷‍♂️ Thanks

[@AndyMechanic]

Hi, the 5.2v Throttle wide open worries me as the supply voltage from the ECU should only be 5v. Check your 5v+ ref wirr from the ECU, if it's over 5v you may have an ECU problem. Cheers Andy

[@user-bp5go8mo5p]

Big UP to KZbin

[@mfx6667]

Its the same test for can am ATV?

[@AndyMechanic]

Hi Mfx, most TPS work in a similar way. Just check you are getting a steady change in resistance (or voltage if you test on the atv with ignition on, as you turn the shaft). If you get any sudden changes them it's junk & you'll need to replace it. Cheers Andy

[@mfx6667]

@@AndyMechanic thanx Man i check the tps its good m'y idle bypass valve its scrap

[@kaseyjohns3929]

Hey I got a 2017 Yamaha yfz450r it's just dumping gas into the motor no matter where I set the vortex ECU it's black smoking turning sparks black does this sound like a bad TPS

[@AndyMechanic]

Could be but just check your injector spray pattern too, needs to be a mist rather than a jet. Also check coolant & air temp sensors for correct spec as if ECU thinks engine or air temp lower than actual it will richen the mixture & may even remain stuck on cold start Cheers Andy

[@kaseyjohns3929]

Okay thanks for the advice I'll try to check them today

[@kaseyjohns3929]

I had the same problem last year I bought a new injector and put it in without even checking the old one and then it worked to find for about 6 months now it's doing it again but I pulled injector out and checked it and I checked the old one and they both sprayed just fine

[@kaseyjohns3929]

@@AndyMechanic I think I'm going to order new ones on eBay I got a TPS sensor in my cart and a coolant water temperature sensor.. is a coolant and a air temperature sensor two different sensors?

[@claudetdubeau2344]

Will the TPS make the bike Miss and run rough

[@AndyMechanic]

Yes, if the TPS signal does not reflect the true position of the throttle butterfly then the fuel/air mixture will be incorrect. Cheers Andy

[@ainstaink8312]

The best way to test the linearity is to use an analog voltmeter!

[@AndyMechanic]

I have to disagree, an oscilloscope has to be the best way in my opinion as it plots the voltage change which can be reviewed and compared to a known good. Thanks for your feedback Cheers Andy

[@ainstaink8312]

Andy, you are right, but considering the cost of oscilloscope, analog meter can still give you a better visual results than the digital one. Analog meters can be picked up for less than $25. But yes oscilloscope would be the best way to go!

[@AhHong-e6u]

Hi

[@joelgardner3352]

I really dislike videos that try to help explain how to test something and there’s so much fluff and unnecessary stuff. Get right to the point please.

[@AndyMechanic]

....to be only given the answer or solution without first an explanation removes any real depth of understanding. Without the knowledge of how the component/system works diagnostic ability is unlikely. If all you want is the answer then I doubt my videos will be to your liking. Andy