OK, cleaned up all the grounds on the car. Gonna chop em all off about 3 inches back next spring and replace them with ring terminals solderd on. All the codes have dissapered except the 1221 code that came up about 20 min in, along with the temp TCS disable, after I heard the chimes and R.E.P. Soooooo, which TPS sensor goes bad? I know there is the one on the pedal and I think there is one on the TB to make sure the blade is moving. Can these be taken apart and cleaned? OR...is there one more little ground or just a little pin on the ground plug I didn't get clean enough yet? This is realy starting to drive me nuts. I think I get it and it kicks into R.E.P. mode when I'm ready to trust it and leave.

 

Most common is a faulty accelerator pedal with APP sensors.There is also an updated TAC module to address this if you have a pre 1999

 

Whats APP stand for and if it is just a funky sensor how will the new TAC help or solve this. Whats the best way to tell which is bad before buying parts?

 

APP stands for accelerator pedal position.There are 2 APP sensors that are part of the accelerator pedal...Without the proper scan tool and diagnostic chart for the code,you will not be able to diagnose without swapping out parts...Based on my experience,the accelerator pedal is the most common fault BUT the throttle position sensor on the throttle body can fail if carb cleaner or water is injested into the throttle body.Fluid will pass by the seal and get into the throttle position sensor.You may want to try a throttle position sensor 1st in that it is less expensive that the throttle pedal assembly...

The updated TAC module will not correct the issue if a part is faulty.It is just and updated part with updated software to prevent glitches in the system which can cause a reduced power mode on the 1997-98

 

OK, after looking over the codes list again( downloadable in Word format in the C5 tech tips section and most complete and organized one I've seen yet!!! thnx!) I noticed that there are seperate codes for the APP so that is rulled out. Now the P1221 code is for TP1, 2 Performance. I guess it means it is redundant and there are more then one in it and 2 Performance not sure abuot.The code before it, P1220 sais TP Sensor 2 Circuit, I don't have but makes me want to know:

What is the difference between the circuit and performance error?

I just found out I have acces to 2 or 3 old TPS from my buddy that put a 99 vette LS1 into his chevy 1500 truck and he pulled all that but he stored it. I'm gonna try a quick swap out too

 

OK, after getting 2 wrong TPS sensors for the car(my favorite local GM dealer folded up and parted out to other nearby ones including the parts lady that I got my parts for employe cost, gonna miss her, and the ones from my buddy where for a Fbody, I hate this aftermarket deal.) I fummed back out to the driveway, pulled my old sensor off. Brought it in and disassembled it on my work bench and took a look. And of course not to my suprise, just another $3 part. Never be able to find or get it for that price, but all in all thats all the materials and foreign labor is worth for the generic piece of poopy. Inside along the outside walls are the four four tracks that the sliders from the middle rotator piece scrap, rub, or track along. On the inside piece, there are four little brushes that are what sraps, rubs, or sweeps across the the ousided tracks. When all apart and looking into the housing with the 4 pads that the brushes scrap on, I could see that one of them was chewd up pretty bad and that another one was on its way. Said"Crap!" to myself. then I looked on the little middle spinner that had the four brushes comming off of it and noticed debris or what I called "$#!&" sticking to the one that lined up and rubbed on the worst track in the housing. So I cleaned it off of the brushes and took a little emery cloth to the inside to clean up the tracks a little bit too then just slapped it back togethor after I bent the brushes to make a "tighter" contact with the tracks. Got it on the car and instantly no more trouble codes or "Reduce Engine Power". Even got rid of the 1515 code that just popped up for the first time when I started it to get it off the street into my driveway. Had it out for about a half our constantly boing between full and no throttle trying to pick up any bad spots, dead spots, or other debris I might of missed when appart. No issue what so ever.

Still going to get a new one. Gonna try and find where my favorite parts lady got moved too. I refuse to pay $113 for a $3 piece of crap. For those that would like to defend it and talk about how advanced and precision the technology is on the TB and TBS is I say "Poopy!!!" Just another lowest bidder item. And the local Chevy dealer mechanic I talked to about my codes that told me "Look man, face it! You gonna have to get a new TAC, TBS, and APPS and hopefully not a PCM." in response to all the codes I was getting before the ground cleaning and the TPS cleaning now..."GO F yourself". Have I ever told you guys how much I hate dealer mechanics?

I'm gonna take it apart again and take pics to post up when I get the new one in. Kinda hard to understand from just a word description.

To all that hepled me track down the multiple code issue THANK YOU! Didn't have a clue untill I read the other post that the entire grounding system was such a piece of junk on these cars. I would have ripped the hole care apart before I came across it.

 

Great job, keep "stickin' it to da man!"