Help with a p0122

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robnb2

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So I have a 1997 GMC sierra with around 132000 miles. She has the 5.7 4x4 with an automatic transmission. Roughly a month ago I had a check engine light pop up for the p0122 (tps low voltage) so I replaced it the tps. It shifted hard from park,reverse,neutral and drive just by moving the shifter. After replacing the tps I also got better gas mileage and throttle response. All great.

Last wednesday when I went to leave for work. I had the same code come up p0122 and extremely hard shifting. After some testing and online research I found that the tps and map sensor shared the same circuit. I tested for voltage and had 5 volts at each sensor and the ground wasnt always there. So I fixed the ground on the thermostat and replaced the map sensor since that was all over the place when I tested it with my multi meter. Also at this time I noticed the coolant inlet and coolant temp sensor where leaking so I replaced those that friday ( I feel like this is irrelevant but I'd mention it anyway).

So today I went to leave for work and the check engine light came on again and the hard shifting. So I grab my code scanner and find the same p0122. I don't believe the tps is faulty because the light comes on without touching the throttle but I'm wrong quite often which leads me to believe an idle issue. So I called in sick today. I cleaned the maf sensor, sensor before the maf sensor not what its called, removed and made sure the egr valve was working. One of the screws where stripped out on the iac so I removed the throttle body to get the screw out by cutting a slot with a dremal. I squirted some maf sensor cleaner in the iac to see if that helped. So I figured I might as well clean it well its removed. So I did that as well.

I didnt know if there was anything else to check so I dont keep having the same issue. I did go for a test drive and it shifted better but I didnt want to clear the service engine light incase i decide my mechanic take a look at it. Sorry for the long post but I figured I'd mention everything
 

robnb2

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I I did attach the freeze frames from my scanner if that is any as well
 

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east302

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Here are the diagnostics from the GM manual for 1998. Not sure if it’s 100% applicable for 97, but maybe it will help.

The complete manuals can be downloaded here:


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