97 XJ TPS issue HELLLLP
 

this is my 2nd post here, but I am not new to jeeps; having owned a YJ and an XJ before; this is my 2nd XJ and I also have a TJ as well.
Sorry to have to do this instead of retyipng the novel but as my computer is blanking out when it wants (took me 3X of rebooting just to register here) so I am gonna try and "copy/paste" from another site that I have listed everything at where I am getting no assistance; most posts there are my own, with few replies in between...
97 HELLLP PLEASE PO123 TPS OK hopefully this one less "cluttered" than the other post I had referenced.

Everything I see online says "clockspring" (my XJ DOES have cruise) but wouldn't I eliminate that possibility, by disconnecting it and seeing if the 7V on the "5v feed" goes away? (it doesn't)
I have almost 7V with the connector to the ECM disconnected that is supposed to feed the 5VREF... meaning that line should be dead.
Long read but PLEASE HELP as I will not pay "dealer" rates and I certainly dont wanna send my XJ to the crusher on this account; though I am close to doing so! HELLLP!
PS; the only differences I see between running the 2 computers I have for this jeep is that the original one wont let it idle below 1250 while the junkyard one will;
I had a 96 one on there; with that computer the gauges were all dead, but the engine would run and it "agreed" with the other 2 computers as to the TPS readings I was getting thru it by way of the scanner.

OK; I have the clockspring all unhooked AGAIN; and it still gives me a TPS code and high voltage a soon as I reset, can't even get back to the home screen from the reset screen on the Snapon acanner before the code returns! so it cant be the clockspring causing the problem like all the "hits" I have on the subject say!
I AN ABOUT READY TO PUSH THIS THING OUTSIDE AND BURN IT
I have only been trying to figure this damn thing out since July!

please can anyone give me a clue where to go next? I am totally flustered and aggravated and cant think straight.

I need to BUMP, I need it to stay towards the top so as many as possible can see it, hopefully someone can (please) give me some direction on this issue.

:wallbash:I'm about to take this thing to the junkyard and watch them :tank: thus jeep....

please? nobody? not even a smart arse offer to buy? (ha ha funny) but seriously I am cornfused and aggravated.

Sorry this XJ is causing so much trouble. You've checked and double checked a bunch of basic stuff so it's got to be something else. Maybe there's a grounded wire somewhere other than the wiring harness that is causing feedback. Or one of the plugs for the wiring harness may be bad. Look for debris in a connector or perhaps a bent pin.

Also, I've never liked remote starters for the same reason you experienced but the problems you had with it and the mass of melted wires are both issues that may be contributing to the problems and may require a second look.

Wish I could help more but the other response were way more knowledgeable than my experience with this.

DougN

I havent read all your posts but just to give you an idea how far "outside the box" you need to think..I had TPS issues and codes for years and changed EVERYTHING multiple times and asked who knows how many experts and mechanics for ideas and no one could solve it. Loooong story short it turned out the TPS and MAP sensor both have a purple/white wire coming off of them which join together to form a single wire which then goes to the ECU. Somehow this wire became disconnected at the junction and whenever the MAP sensor got to the point it tried to send a voltage signal to the computer it had nowhere to go except to the TPS so that would cause the voltage at the TPS to be read as wrong by the ECU and it would start adjusting the TPS (Needlessly) and the engine would start acting stupid and I'd get the check engine light and TPS code showing up when there was actually nothing wrong with the TPS at all. Drove me insane! :icon_biggrin:

thanks for the suggestion but I have replaced the whole wiring harness TWICE now; I wouldn't think that all 3 (the orig and both replacements) would have the same problem now, or would they?
the melted wires were on the "engine" wiring harness that lays on the intake manifold. that part of the harness has "only" been changed once. I have another here though.

I was wondering about the MAP; the difference in voltage between the TPS plugged in and disconnected, is about 1/4 volt; which by itself is the baseline reading I oughtta have with key on engine off....
there are 4 or 5 things that get fed from the same 5VREF "orange" wire that feeds the PS; and the TPS is either 2nd or 3rd in "line" CPS is 1st according to the schematic the MAP is 2nd and the TPS is 3rd in line; the Dist pickup and (I forget what else) is after in the chain; if I disconnect everything in that chain and plug in each thing individually, I get the same 1/4 volt difference in TPS reading (with the TPS still unhooked) on the scanner, as I do with everything else plugged in and "just" plugging/unplugging the TPS.
I hope that what I'm saying make sense.

please don't stop the train of thought now.... BUMP

So just to be clear. Do you have it all put together as best you can right this minute? And if you do and you go and try and start it what exactly happens?

yeah it is prettty much together;
I "try" and start it, fires right up. I try to give it "any" gas it farts and putters.
I have the clockspring and the TPS unhooked right now; no change;

I get a PO123 as soon as I start it, and I cannot let my finger off the button on my Snapon scanner fast enough the Check Engine light immediately pops back on with the same damn PO123.
i have replaced parts out the a$$ (computers wiring harnesses) and have more time in this thing chasing wiires with a Fluke meter than I can count. same thing.
in fact I dont even have to start the engine the PO123 comes as soon as i turn the key on.
If you have not please read thru my linked thread, "what happens" is detailed as well as "what I have done" to try and remedy the problem.

Only difference among parts so far; between the original computer and this one, the original will not allow it to idle below 1250 RPM. the current one lets it idle and smoothly around 800 or so. (til I give it any gas)

it makes NO difference with TPS hooked up/unhooked,concerning how it runs;
only difference there is unhooked I have 4.69V TPS reading on the scanner verified by the fluke.
I connect the TPS my reading goes to 4.94V; I should have 1/2 a volt or less. (all readings shown at dead idle position)

and the last time I tried to drive it no matter how gentle I was on the gas, it wound up to redline before the trans would shift
I attribute that to the computer thinking the throttle is always 87% mashed as the scanner says it is (I get the same reading when TPS is disconnected!

and; what really baffles me; the 5VREF (orange wire at TPS) is supposed to get that 5VREF FROM the computer. so why then if I unhook the "A" plug (closest to the core support)which is supposed to feed that 5V; do i still have nearly 7V, on that wire? With the computer plug disconnected that orange wire should be dead. and how do I get voltage on the brown/yellow "sensor return" (as the factory service manual pinout chart calls it) when that is supposed to be a GROUND CIRCUIT? if I can figure this out it will solve my problem.

Hello. I havent given up as I enjoy a challenge so I will ponder your situation more and next time I am in the junkyard will look at a '97 specifically to see what wires do what. I was under the impression that the ground circuit on these things was the black/light blue wiring. Doing a quick search I also saw "clock spring" come up over and over relating to TPS problems so maybe simply disconnecting it won't cure the trouble if a voltage signal is trying to go thru there and ends up at the TPS instead of its planned destination? (As the MAP voltage did in my XJ).