TPS input voltage 4.45.... do I need a new one?

I was adjusting my TPS and my input voltage was 4.25 to start so I moved my TPS and the highest reading I could get was 4.45. I know it should be around 5 volts but I cant get it past 4.49. Do I need to buy a new TPS to get the volts back up to 5?

No the 5 volts comes from the ECU to the TPS not from it. You could just have a bad ground.
Also your readings don't make sense. The output can't be greater then the Input.

You need the same 5 volts in to the MAP MAT CTS and the TPS thats what powers them.

ok so when I was doing all this, this is what I came up with:

black wire in D, and red wire in A - 4.25

black still in D, and red moved to B - 4.71

I read that B,D was your output and that never changed even when I moved the TPS

so when I divided 4.71 by 4.25 I got 1.108 which is 110.8% and I need 83% which means my input (4.25) needs to be right above 5 volts
I moved the TPS as much as I could to change the A,D to 4.45 and thats as high as I got it.

Is this TPS for the automatic? A to B is the input 5 vdc. B is ground and all mersurments are taken from B.
B to C is the input to the ECU and where you want the check the adjustment.
D and C is for the transmission.

The three wires cloest the the TB are the ones you want to be using.

ya this is for an automatic but when I did this I used the square plug-in not the flat one you have in the picture. could that be the problem?

hockey10588 said:

ya this is for an automatic but when I did this I used the square plug-in not the flat one you have in the picture. could that be the problem?

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Sounds like it to me.

sounds like you're on the right track. Maybe this will help
http://autorepair.about.com/library/faqs/bl232i.htm

http://autorepair.about.com/library/a/1i/bl232i.htm

The above instructions are a little confusing in step 3. To make it simpler...first find out the input reading and calculate the percentage and adjust the TPS to the adjusted voltage.

I'm bad at math but forced myself to figure the numbers out for my own TPS settings.

As an example...

My Jeep's TPS voltage was 4.5

So you gotta find 83% of 4.5Volts.

With a calculator it goes like this 4.5 x .83 = 3.735

You set your output at 3.73 volts with a closed throttle?

voltage out divided by voltage in should be in the neighborhood of .8 volts. I don't understand how people can set their TPS to these whack settings and still run.

So I'm wrong? Mine runs fine but if i'm wrong that's ok too...

philip_g said:

sounds like you're on the right track. Maybe this will help
http://autorepair.about.com/library/faqs/bl232i.htm

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ya I used that site to guide me but it says to use the 4 way connector so I used the square one. On my automatic jeep I have 2 plug-ins. one is flat with 3 wires going to the TPS that are labeled A,B,C and one is square with 3 wires going to the TPS and on the bottom it says C,D but there is no wire in the C slot.

philip_g said:

You set your output at 3.73 volts with a closed throttle?
voltage out divided by voltage in should be in the neighborhood of .8 volts. I don't understand how people can set their TPS to these whack settings and still run.

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LMAO Phillip, especially after you skooled me on the diff between auto and manual trannies.

With the manual, output voltage should be 16% of input, so take whatever input value and mulitply it by 0.16.

With the auto, output voltage should be 83% of input, so multiply input by 0.83. Also note that you can be in a range of 82.5% to 83.5% with the auto.

So who's correct...Hypoid or philip_g?

Johnny V said:

So who's correct...Hypoid or philip_g?

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Beats me, the howto I linked was for autos so I'd go with what that says.

Maybe both!!!! LOL
phillip_g questioned this in another thread, what I had yet to learn is that the auto and manual work opposite of each other, and set up opposite of each other. With the RENIX:
Auto tranny output voltage starts high at closed throttle, and drops as throttle is opened.
Manual tranny output voltage starts low, and increases as throttle is opened.

Past that I defer. Before I discovered this valuable resource, I went to my local library and used their subscription to ALLDATA. In that system I used vehicle specific filters. So if you have a '90 Limited, ALLDATA will have me repeating the correct info. LOL

hockey, langer1 mentioned the ground connection. Just for grins measure between pin D (the ground wire) and the intake manifold. ALLDATA says that if there is more than 0.1 volts, you have an inadequate ground connection. ALLDATA recommended tapping the ground wire and adding another ground point. When I measured from pin D to chassis ground I had 1.0 Volts. Where-ever that wire grounds, it had too much resistance! A second ground point under the hood fixed that problem.

Past that I had an extra set of hands to help me. I struggled by droplight 'till frustration got the better of me. The next afternoon, my wife came out and held the meter while I used the probes. I sorta wish I had got that frustrated much sooner. LOL

Hang in there, Mike

dude I give up.

Wish i was closer to you guys I would calibrate your TPS. I purchased the snap-on MT2500 off of Ebay and it hooks up and displays the TPS value. You just turn the TPS until you are on the money.

Before I owned the test set I also did the back probe method. It is true the have you calibrate on the transmission connector instead of the engine connector. I set my TPS using a multimeter, thought I had it set right. I even made a spread sheet with voltages 3.0 to 5.0 by 0.01 volt increments. I then multiplied the value by .83 and put the 3 digit result in the second column. If you are doing the mulitmeter method this look up table is VERY nice to have while your head under the hood.

I then took it into the dealer for a low MPG problem - turned out to be a bad EGR - and the mechanic told me "I reset your TPS since it was off." I had the TPS installed only a couple of weeks at the time.

I agree the back probe method beats no calibration. I think the error found can be explained by the voltage drop from the TPS back to the computer. By using the mulitmeter method you do not account for the drop, by using the test set the voltage drop is accounted for by the tool.

I looked at the autoxray tool at their web site, www.autoxray.com and found it would give TPS value but did not give you info to set TPS. The problem it does not cover RENIX (87-90) XJs controls.

This it the time you need to be buddies with a mechanic who can set it for you in exchange for a 6 pack of cold ones

hockey10588 said:

ya I used that site to guide me but it says to use the 4 way connector so I used the square one. On my automatic jeep I have 2 plug-ins. one is flat with 3 wires going to the TPS that are labeled A,B,C and one is square with 3 wires going to the TPS and on the bottom it says C,D but there is no wire in the C slot.

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Forget about C,D use ABC on the flat plug.

sooner or later I'll learn that 80 bux of diag time is worth it.

Use the flat connector as that's what the engine computer sees. The square one is for the trans computer which isn't nearly as picky about the TPS adjustment.