can anyone tell me what the symptoms of a bad tps would be?
like what is the purpose of the idle switch? what would it cause if it were bad?
like what is the purpose of the idle switch? what would it cause if it were bad?
symptoms of failing tps?
- Thread starter supraduper
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Idle switch tells the computer the throttle is closed(basically).
You can test the tps with a volt meter.
E2 .025v closed, .025v open(ground)
IDL .029v closed, 4.75v open
VTA .536v closed, 3.5v open
VC 5.01v closed, 5.01v open
The desciption of which pins are what in the tps is in the tsrm.
You can test the tps with a volt meter.
E2 .025v closed, .025v open(ground)
IDL .029v closed, 4.75v open
VTA .536v closed, 3.5v open
VC 5.01v closed, 5.01v open
The desciption of which pins are what in the tps is in the tsrm.
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Another symptom of a failing TPS is a slight hesitation/miss at a given throttle position. What happens is the TPS will develop what's called a "Flat Spot". Basically, it will wear out in the spot that your pedal is at most.
cuel;1453436 said:
The TPS is not an on/off switch, just doing these tests is not enough. Assuming the above information is correct, VTA should be the signal wire. The voltage should increase smoothly and uniformly as the throttle is opened slowly. anything other than a linear increase would indicate a "flat spot" as kenny stated.
jdub;1453793 said:The IDL signal on the TPS is an on/off switch
True, but it is also not the primary fuction of the TPS. TPS often only have 3 pins; power, ground and signal.
It's a primary function on this TPS...tells the ECU when to go into idle mode. And, since we're talking about a 7M here.....
thanks for the responses... i guess i should mention the problem i am having.
when cruising at any given speed... when i let up on the throttle i feel a harsh buck when i hit the throttle... i have to move the pedal extremely slow/ soft to get a smooth transition from zero throttle to any throttle...
i assumed it had something to do with the idle switch. but the colors in the ewd didnt match up to my harness.. i have a 86.5
when cruising at any given speed... when i let up on the throttle i feel a harsh buck when i hit the throttle... i have to move the pedal extremely slow/ soft to get a smooth transition from zero throttle to any throttle...
i assumed it had something to do with the idle switch. but the colors in the ewd didnt match up to my harness.. i have a 86.5
It almost sounds like a sticky throttle cable or throttle linkage. It's kind of a pain; but, you can try to lube the throttle cable. The linkage and pulleys are easier to get to which makes them easier to lube.
Another thing it could be is that the throttle cables are not routed properly. That'll put additional stress/resistance on the cable moving inside the sleeve.
For example, I've seen a few cars where the linkage was run under the EGR Valve and/or bracket instead of over the top. That can cause a few things to happen. The pedal could be hard to press down initially, have a hard time coming up, or worse causing the pedal to get stuck down.
This sounds like what you could have going on.
Make sure all of that is routed correctly...
Another thing it could be is that the throttle cables are not routed properly. That'll put additional stress/resistance on the cable moving inside the sleeve.
For example, I've seen a few cars where the linkage was run under the EGR Valve and/or bracket instead of over the top. That can cause a few things to happen. The pedal could be hard to press down initially, have a hard time coming up, or worse causing the pedal to get stuck down.
This sounds like what you could have going on.
Make sure all of that is routed correctly...
i think you're right. i noticed the butterfly moves freely when moved at the linkage but it slightly binds at the horizontal wheel where the cruise connects to... there is a bit of play in that wheel and i have tried lubing it to no avail... do i just replace it? or maybe theres another way?
lewis15498;1453477 said:
I did forget to mention that vta should ramp up smoothly from closed to wot. Thanks for clearing it up
jetjock;828954 said:Right hell, it looks about perfect. Assuming no flat spots in VTA at around 25% throttle (typical of worn sensors) you've got a fully functioning and properly installed TPS there.
VTA when closed is right at the midpoint of the 100 mv to 1 volt spec and although the TRSM states VTA open should be 4-5 volts 3.5 is typical. In fact I've never seen one beyond that. Bottom line: VTA falls between 100 mv and 4.8v throughout the range of throttle travel. Sorry, no code 41 for you.
VC is also fine. IDL is OK too although I was surprised it's 12v when high. I could have sworn it was pulled up to 5v like the other sensors but now that I check the book it should be battery voltage. The main thing is yours is showing a solid ground when closed and a good pull up to +12 when open. No code 51 for you either, at least not from that cause.
I'd say you're good to go. Cold and warm idle control should be active, as should idle up for AC compressor and headlight operation. Remember, if the TB is the older style with a manual bypass screw make sure it's fully closed.
One more thing. Technically you ought to be using E2 (sensor ground) and not battery negative when measuring sensors but since they're (sort of) connected together inside the ecu it's not a big deal. In the future try and reference E2. That way you'll avoid the .025 volts you saw between E2 and battery negative. It's nothing to lose sleep over though.
Nice job. Not like Mode $06 is it?
so the problem was definitely in the roller part of the throttle linkage... the roller that drives the actual butterfly linkage... not the horizontal wheel where the cruise connects to..
the roller was gunked up with what looked to be dried up anti-seize..
cleaned it up and it made the problem clear up...
the roller was gunked up with what looked to be dried up anti-seize..
cleaned it up and it made the problem clear up...
In reference to the quote above: Though unsure about the 7MGE on the turbo IDL is pulled up to 5 volts when open. The book is wrong. I'd be very surprised if the GE was different. Also, code 41 can occur even though VTA passes a resistance test. It occurs whenever IDL remains low and VTA goes above 1.5 volts. In such a case the 41 will be misleading. The lack of a 51 would be the real clue.
Do that (because I can't) but I seem to remember settling that question some time back. Been so long I may have forgotten though...
Sure enough, it tested at 4.75v with the throttle opened. CRE tested his as well for me(thanks again), and his was 3.48v(a little low?). Strange the book(All Data as well) says it should test 10v - 14v, but vc should only be 4 - 6. I was gonna get a new sensor to test, but no one had it in stock. It was a new Toyota sensor I put on Austin's car(90 GE) in the original thread. He couldn't get to his car to retest it.
Oh, sorry C.J..... I didn't measure the IDL switch, that's the range of my VTA signal that I sent you.
Makes sense IDL is pulled up to 5 because the system uses that level for all sensor monitoring. The TPS itself should have no bearing on the voltage since it's done by a pull up resistor in the ECU. I suspect the TSRM mistake comes from the P7 systems Toyota used prior to the introduction of TCCS because in P7 the sensors were 12 volt. That along with integrated ESA and ISC is what separates TCCS from earlier versions. And yes, wide open VTA is typically around 3.5 vdc, not the 5 specified. Yet another mistake in the book...
Just because it is somewhat related I'd like to add that when I was experimenting with the Enhanced TPS functionality in the MAFT Pro's newer revisions I found that I got error codes if the TCCS was supplied with a signal of 3.5v. I didn't know what was up with the errors and JetJock pointed out that it was probably due to the signal being higher than 3.48 (or something along those lines). I reduced the voltage from the Pro to 3.48v and no more errors.