2003 Check Engine Light-Sometimes?

I have had my 2003 Grand Cherokee for about 8 months, and throughout those eight months the check engine light has been around. Not all the time just for like a day here or a day there or an hour here or an hour there, then it's off for like a month or a week. Lets just say it is real inconsistent. Any ideas?

For now, check for stored fault codes:
Put the key in the ignition, turn the key to the On position (not the start) then turn the key to the Off position, repeat two more times without delay (for a total of three) leaving the ignition in the On position at the third (last) "On".
In place of the odometer digits, you should see "done" if no fault codes are present, or a number preceded by a P as in p**** if fault codes are stored.

If there is a fault code/s, write them down and post them here.
If not, try the key on/off retrieval method when the check engine (MIL) light comes on again.

I did what you said and one code came up...
P0122

From what I've researched it seems like this code means, Throttle Position Sensor Voltage Low. If this is true how hard is it to change and how much will this set me back?

TPS is very easy very easy!!! It will set you back about $75 at the dealer for the part alone. the part is located on the left side of the throttle body and is held in place by 2 small screws thats it.

TPS is very easy very easy!!! It will set you back about $75 at the dealer for the part alone. the part is located on the left side of the throttle body and is held in place by 2 small screws thats it.
You can't just swap out the TPS - you must have a precision voltmeter to be able to adjust the switch position for the proper voltage, which is very critical. If you are throwing a code that the voltage is low, it may be possible to just re-adjust it, but it is probably bad.
Check out this link for some info on a 97 JGC TPS http://autorepair.about.com/library/faqs/bl069f.htm

Hope this helps, or at least steers you in the right direction.

You can't just swap out the TPS - you must have a precision voltmeter to be able to adjust the switch position for the proper voltage, which is very critical. If you are throwing a code that the voltage is low, it may be possible to just re-adjust it, but it is probably bad.
Check out this link for some info on a 97 JGC TPS http://autorepair.about.com/library/faqs/bl069f.htm

On 1999-2004 Grands the TPS is not adjustable.
The error code points to the TPS - you can check it with a digital or analog volt meter:
The PCM receives an input signal voltage from the TPS.
This will vary in an approximate range of from .26 volts at minimum throttle opening (idle), to 4.49 volts at wide open throttle.
The voltage changes should be steady and linear as the position of the throttle blade changes when opening the throttle.

Are you having any driveability problems? A bad TPS usually shows symptoms since it is used in the calibration of fuel delivery, ignition timing and other variables.
If it drives ok, it's possible that the TPS is intermittent, as in a loose wire, bad ground etc. causing the sporadic check engine light.

If I look up jeep grand cherokee throttle position sensor it comes up on ebay for 28 bucks, can anyone type that in and let me know if that is what I need.

On 1999-2004 Grands the TPS is not adjustable.
The error code points to the TPS - you can check it with a digital or analog volt meter:
The PCM receives an input signal voltage from the TPS.
This will vary in an approximate range of from .26 volts at minimum throttle opening (idle), to 4.49 volts at wide open throttle.
The voltage changes should be steady and linear as the position of the throttle blade changes when opening the throttle.

Are you having any driveability problems? A bad TPS usually shows symptoms since it is used in the calibration of fuel delivery, ignition timing and other variables.
If it drives ok, it's possible that the TPS is intermittent, as in a loose wire, bad ground etc. causing the sporadic check engine light.
Didn't know that - thanks for the correction. I had had experience with the ones on my 97 and 87 Cherokees, so I assumed that it was still the same.

I am in the process of ordering my throttle position sensor. One will be in tomorrow from NAPA, can anyone help me out with the installation of it? I understand it is pretty simple, but can anyone tell me if I will need any special tools or what is involved?

From what I have researched when installing some TPS you have to do a voltage test with a breakout box or something of that sort, but when I called the dodge dealer he said he never heard of that for an 03 grand cherokee?

O.K. cancel all my other stupid posts, I went back and read all of what you say and I understand now. I have one last question, do I need to test the voltage after I replace the part or is that just a preliminary thing to see if it bad? Since I am now having drivability issues related directly to the TPS, I'm pretty sure this is my problem. (Next time I will read all before I ask redundant questions, Sorry!) and Thanks!

... do I need to test the voltage after I replace the part or is that just a preliminary thing to see if it bad?
No, you have the codes and drivability issues, just replace it.

I replaced the part yesterday, is there a way to now reset the computer? So the error code can be reset?

This just happened to me today, fault code P0122. What did you do with new part? Did you just swap it without doing anything else?