TPS turning on CEL immediately after clearing it?

Have a 2000 Jeep cherokee. 4.0/AW4.

Motor has a knock to it. Bought it for cheap as the previous owner cracked the head, and coolant was mixing with the oil. Motor didn't run when i bought it, so i slapped an 0630 head on it. After that, that's when i realized it knocked. Obviously the bottom end is smoked. But that's not my concern.

My concern is the TPS. Jeep has a code for the TPS. I cleared it with my code reader, and it came back on immediately for it again. I have no problems putting a bottom end in the thing, but i'd like to figure out why this is doing this first before i put a motor into it for nothing.

TPS i pulled out of a running/driving normally cherokee.

What trouble codes did you download ? Have you looked them up in your Jeep Factory Service Manual, or the GOOGLE ?

You might get by with just a new set of bottom end bearings if things aren't f'd up too bad. The longer you wait, the less likely to be able to pull it off.

Tim_MN said:

What trouble codes did you download ? Have you looked them up in your Jeep Factory Service Manual, or the GOOGLE ?

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old_man said:

You might get by with just a new set of bottom end bearings if things aren't f'd up too bad. The longer you wait, the less likely to be able to pull it off.

Click to expand...

Jeep is throwing these codes;

PO123 - Throttle/pedal position sensor A circuit high input.

P0122 - Throttle/pedal position sensor A circuit low input.

I googled it before, and only one guy seemed to have the same issue as me. Turned out for him one of the wires was chaffing on the back of the head grounding out the sensor. I did a really quick look but didn't see anything. (Obviously i need to look harder to rule that out), but i'd like some more feedback before i go fourth and put a new motor into it.

Another thing i noticed is the jeep idles fine. If i rev it up to like 2,000-2,200 RPMS and then let off the pedal instantly the jeep won't idle; it'll die out.

Do all three of the wires from the TPS go straight back to the computer? (Is it possible to simply rerun those three wires?)

As for changing bearings in the bottom end i'd prefer to put a bottom end into the jeep i know is good. I seriously drained like 6 quarts of coolant out of the oil, and then 6 quarts of oil.

Another cause of false TPS code is the airbag clockspring in the steering column.

No wiring diagram will show it but it shares a 5v feed with the TPS. When the clockspring shorts, it causes a TPS code.

Digger87xj said:

Another cause of false TPS code is the airbag clockspring in the steering column.

No wiring diagram will show it but it shares a 5v feed with the TPS. When the clockspring shorts, it causes a TPS code.

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Wouldn't my airbag light be on or not necessarily?

That would cause the instant on TPS light i have?

Kingkong0192 said:

Wouldn't my airbag light be on or not necessarily?

That would cause the instant on TPS light i have?

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not necessarily

yes.

you can pull the cover on the steering column and unplug the yellow connector and see if the problem goes away.


TJ wranglers had the same problem.. had one kick my ass when I worked for the dealer.

Digger87xj said:

not necessarily

yes.

you can pull the cover on the steering column and unplug the yellow connector and see if the problem goes away.


TJ wranglers had the same problem.. had one kick my ass when I worked for the dealer.

Click to expand...

Much appreciated. :thumbup:

I'll try that when i get the jeep back in the garage. Rainy and snowy here at the moment.

Just tried unplugging the airbag; same problem.

I did notice that the gas gauge is also acting up. Said i had half a tank of gas, then instantly tanked down to no gas. Cycled the key again, quarter tank of gas.

After clearing the CEL it didn't go off AT ALL. Cleared two of the three codes and the PO123 light stayed on.

Any other ideas? Bad ground? Chaffed through wire?

One of the gas tank straps is broken and the gas tank is sitting kind of cockeyed but i'd think it would at least read the same level as opposed to jumping all around. Jeeps been sitting in the garage for ten minutes so the fuel isn't sloshing around.

Fix any known problems, like the gas tank. Google the trouble codes, and then fix them.

Ok. Gas tank is fixed, new motor is in. Only thing left is this PO122 code, and figuring out what's up with my gas gauge.

I noticed this tonight. Do these two things share a ground or something that would explain this?

Gas gauge doesn''t work (pegged at E) and i have a code P0122 (TPS low input) that will not turn off. When i clear it, it clears for maybe half a second then instantly turns back on. I noticed though that when i'm clearing it for the half second it does clear my gas gauge moves off of E, starts going up, and then as soon as the CEL comes back on the gas gauge goes back down to E.

Also just noticed that i have ten pounds of oil pressure with the key on.