00 XJ. 4.0/Automatic.

Bought the jeep with a blown motor (previous owner got it from some lady that didn't realize the head cracked and it smoked everything). He said when he got the jeep there wasn't even a TPS in the thing (??).

Anyways, i put a 99 4.0 into it.

Only issue i'm having now is the CEL light will not turn off. It has a code for P0122 - Throttle/pedal position sensor A circuit low input.

As soon as i reset the light with my code reader it turns off for maybe half a second and then immediately turns back on.

I also noticed the gas gauge isn't working correct (sometimes when the CEL goes off for the half of second it's off the gas gauge starts working again but the second the CEL lights up again it stops working.

I also noticed that the oil pressure says that i have 10 pounds of oil with the jeep off and the key on.

Any ideas? Some ladies coming to look at this jeep sunday and i need to figure this out fast.

 

You put a TPS in, I assume? +5V at the connector that plugs in to it?
Take a look at the wiring harness near the back of the valve cover. Some have reported the harness rubbing on a bolt back there and shorting.
If your oil pressure reading drops to zero when you unplug the sender, it's a bad sender.

 

Hahaha that would be the day. Yeah, i swapped an entire throttle body onto the 00 intake. Throttle body came from a running/driving cherokee.

Haven't checked for volts at the connector yet. Going to look up that procedure now. Can't remember which of the three is a ground and which is the supply.

However, i did unplug the TPS connector, and then unplug the connector where it goes into the ECU. Set my multimeter to the setting where it beeps if the two things are connected. All three of the wires on the TPS are making it to the computer. I guess one could still be pinched and shorting out, but they are getting to the computer.

So leave the key on, and then unplug the sender and see if the reading drops to 0?

 

Here's some TPS test procedures:


You can use a safety pin to back probe the connector.