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Throttle position sensor output voltage

Tiny
BMXWAYNE
  • MEMBER
  • 1993 PONTIAC SUNBIRD
  • 4 CYL
  • FWD
  • MANUAL
  • 248,000 MILES
I checked my tps as per instructions in my chilton manual and at idle position it reads 5 volts and decreases to.47 volts as I open the throttle to full my chilton manual says it should be just the opposite so is the manual wrong or is the tps bad
Saturday, November 26th, 2011 AT 8:51 PM

31 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
THROTTLE POSITION (TP) SENSOR
Install jumper wires to enable connection of a DVOM in parallel between TP sensor harness connectors. Connect DVOM positive lead to Dark Blue TP sensor signal wire terminal. Connect negative lead to Black, Black/Orange or Purple sensor ground wire terminal. See Fig. 3. Turn ignition on, with engine off. Signal voltage should gradually change from less than one volt at closed throttle to about 5.0 volts at wide open throttle position. If reading is not as specified, adjust or replace TP sensor. See ADJUSTMENTS article in this section.
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Saturday, November 26th, 2011 AT 8:58 PM
Tiny
BMXWAYNE
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  • 58 POSTS
Ok so the tp sensor is bad then that is what I thought but just wanted to double check info
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Saturday, November 26th, 2011 AT 9:00 PM
Tiny
WRENCHTECH
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  • 20,758 POSTS
I would guess you may be doing something wrong. Even a bad sensor won't act that way.
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Saturday, November 26th, 2011 AT 9:44 PM
Tiny
BMXWAYNE
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I checked exactly how the chilton manual said to
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Saturday, November 26th, 2011 AT 10:52 PM
Tiny
WRENCHTECH
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It could be installed incorrectly.
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Saturday, November 26th, 2011 AT 10:58 PM
Tiny
BMXWAYNE
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  • 58 POSTS
How could it be installed incorrectly
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Sunday, November 27th, 2011 AT 3:50 AM
Tiny
BMXWAYNE
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  • 58 POSTS
Ok I installed a new sensor correctly and still get the same reading of 5 volts at idle closed and it decreases as I open the throttle there is no short between wires what the hell else could cause this sorry about the mildly gruff language but I am frustrated to no end with this issue
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Wednesday, November 30th, 2011 AT 12:07 AM
Tiny
WRENCHTECH
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What color probe are you putting on what color wire?
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Wednesday, November 30th, 2011 AT 12:15 AM
Tiny
RASMATAZ
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Try reversing the DVOM leads and read again
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Wednesday, November 30th, 2011 AT 12:21 AM
Tiny
BMXWAYNE
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  • 58 POSTS
Red test lead to white black test lead to blue or as described by my chilton manual red to bottom and black to middle
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Wednesday, November 30th, 2011 AT 12:24 AM
Tiny
WRENCHTECH
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White? There is no white wire. There is a gray wire and that is the wrong one. You should have the black lead on the black wire and the red lead on the blue wire.
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Wednesday, November 30th, 2011 AT 12:26 AM
Tiny
BMXWAYNE
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Ok I tested on the wires as you said and get a reading within spec but when I check for dtcs I am still getting one for the tp sensor what else could cause that
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Wednesday, November 30th, 2011 AT 12:41 AM
Tiny
WRENCHTECH
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Any of the related wiring or the PCM itself.
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Wednesday, November 30th, 2011 AT 12:42 AM
Tiny
BMXWAYNE
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  • 58 POSTS
I do know that I have a failing fuel injector I have a replacement for that on the way
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Wednesday, November 30th, 2011 AT 12:43 AM
Tiny
BMXWAYNE
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I replaced the pcm less than a year ago there must be a bad connection somewhere then
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Wednesday, November 30th, 2011 AT 12:45 AM
Tiny
WRENCHTECH
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Perform the same test on the same wires at the pcm and see if you get the same results.
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Wednesday, November 30th, 2011 AT 12:47 AM
Tiny
RASMATAZ
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I have a funny feeling about the brain here-Wrench which was my next step on ur suggestion
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Wednesday, November 30th, 2011 AT 12:50 AM
Tiny
WRENCHTECH
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We'll find out when he finishes the test I just gave him.
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Wednesday, November 30th, 2011 AT 12:56 AM
Tiny
BMXWAYNE
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  • 58 POSTS
Ok got the same reading at the pcm now what
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Wednesday, November 30th, 2011 AT 1:14 AM
Tiny
WRENCHTECH
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If you're absolutely sure that that code is resetting immediately, then you have a bad PCM. It would be better if you had a scanner to look at the TPS numbers that the PCM is seeing.
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Wednesday, November 30th, 2011 AT 1:17 AM

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