Throttle Position Sensor - Low Voltage

mjleg

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Hey guys,

My truck periodically throws a low voltage tps code. Instead of checking the sensor, I just bought a new one and threw it on. Of course it still throws the code though. It seems to happen if I floor it instead of using a steady foot. Is makes sense.

Anyway, so it is still throwing the low voltage tps and these tps sensors are not adjustable. Any one experience this before? My electrical knowledge is very limited so I was hoping an engine guru could post a couple suggestions.

Thank you!
 

SAATR

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Potentially a short or bad connection in the TPS wiring. It would be a good idea to check the harness for rubbing/breaks and check continuity with a multimeter. Also inspect the pins and make sure that they are snug and not bent/twisted.
 

mjleg

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Thanks. Ya, that was the next step. I haven't had the time to spend on it lately. Tomorrrow I will have to through and check all of that. Very frustrating... It is intermittent. Oh well. I am wondering if it is related to the distributor cap and rotor. I remember a while back I felt like when it rained it would hesitate sometimes. I wonder if it is losing voltage there...?

I guess I just have to check... I hate electrical. I love just changing the part, and that is that.... damn.
 

SAATR

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Yeah, chasing electrical gremlins is a bummer. Hope you get it solved!
 

StreetStylen

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Just wondering if you ever found a solution, I have been chasing p0122 for months.

96 Tahoe 2dr 5.7l 4x4.
A little history on the p0122:

Originally I had a misfire on #6, I found out that the intake gasket was in 3 pieces and the coolant passages where almost completely clogged. After doing the rebuild I had an issue with the distributor and getting it to set right. I understand the plus or minus 2 degrees and finally got that p1345 to go away. Now I have been chasing p0122 for months.

The truck will run but very ruff and wants to die, has no power and seems to be running rich.

I have checked most of the wiring and taped up any that look cracked or worn. tps voltages are good, tps and egr have been replaced. Also replaced driver side upstream o2 that had bad wiring. Just put in a new battery and cleaned up the big wires and grounds. I am not familiar with live data yet, so I am not sure what to look for to find what might be bringing down the volts at the pcm and causing this issue.

The first issues I see are the throttle position is at 4%, the fuel pressure is around 50psi and the timing is showing -.24. is this creating my issues with tps p0122? I am not sure what these values should be or how to fix them if they are off.

I just rechecked all senors for opens, none found. I just rechecked readings on tps, these are the the voltages I recorded: grey wire 5v, black wire 12.6v and blue .52 then only to 4.3 at wot which is short from 4.5-5 correct? The only other thing out of the normal is the throttle cables do not have the stock hold downs, could this cause a problem with the position of the cables? I just want to narrow this down but I am lost as to what could b throwing the code is all the tps values are correct.

Any help would be very much appreciated!! Sorry this was so long but I have been on a couple other forums with not much luck.
 

JonZ71

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I'm thinking your out of time. take distributor out and re check TDC and reinstall.
 

StreetStylen

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just did some more investigation. Turned the throttle screw to make the volts read .6 with ignition on not running and wot closer to 4.5, drove around a lot and the light has not come back on! Not sure if this is the 100% fix but I feel better. The shutter has gone away and the truck feels a lot stronger.
 
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