check engine light

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  #1  
Old 07-29-06, 12:55 PM
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check engine light

I have a 99 jeep wrangler sport. Yesterday the check engine light came on. I took it to Auto Zone to have it tested. They really couldn't tell me much on the reading so I hope someone here can help. The reading is this:

The PMC has determined that the actual input from the throttle position sensor does not match the calculated input for the throttle position sensor derived from the input gathered from other sensors.
IE: Manifold absolute sensor pressure, idle air control motor position, etc.
 
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Old 07-29-06, 04:10 PM
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It should have a "P" code if it can retrieved the info from PCM.
 
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Old 07-29-06, 09:16 PM
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I don't know anything about Jeeps, however a TPS going bad happens.

I had a bad TPS on my Ford Explorer a couple years ago, and was actually able to pull it out, clean it with carb cleaner, and replace it. Never had the problem again.

Not sure if all TPS' can be cleaned though, as TPS' work differently car to car. If it can be cleaned, and it fixes your problem, it will save you some bucks.

DO a search on Google. Looks like the problem you are having with your make and model is common. There are some good info on how to check the problem yourself. I didn't post any links because I am not sure if that is ok here. (new to this board)

Good luck!
 
  #4  
Old 07-30-06, 01:22 PM
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The IAC and the TPS will not usually both go at the same time. your fuel injection system probably needs to be cleaned. Put some cleaner in the gas and see if the light goes out after a few miles. Both of these sensors are pretty cheap as far as jeep parts go. I would not buy them from a dealer as they will cost two or three times more than at the auto parts store. They are both mounted on the throttle body under the air filter and the wire unplugs from them and then you just take out a couple of metric screws. After the new ones are on reconnect the wires and then leave your negitive battery cable disconnected for a few minutes to reset the computer.
 
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Old 07-30-06, 01:46 PM
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Originally Posted by New guy
It should have a "P" code if it can retrieved the info from PCM.
It was p1210 with the message I explained above.
 
  #6  
Old 07-30-06, 01:57 PM
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The possible causes according to Jeep for your DTC are:

-problem w/ harness or connectors
-TPS defective
-MAP defective
-PCM defective

The most likely cause is the TPS. To test the TPS you can use a digital volt meter. Backprobe the middle wire on the connector at the TPS and check voltage at idle and at wide open throttle. Voltage should be greater than .26 volts but less than .95 volts at idle. At wide open throttle, the voltage must be less than 4.49 volts. The voltage should increase gradually as the throttle plate is slowly opened from idle to wide open throttle. You can do this test with the engine off and the key on.
 
  #7  
Old 07-30-06, 02:04 PM
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Originally Posted by davzack
The possible causes according to Jeep for your DTC are:

-problem w/ harness or connectors
-TPS defective
-MAP defective
-PCM defective

The most likely cause is the TPS. To test the TPS you can use a digital volt meter. Backprobe the middle wire on the connector at the TPS and check voltage at idle and at wide open throttle. Voltage should be greater than .26 volts but less than .95 volts at idle. At wide open throttle, the voltage must be less than 4.49 volts. The voltage should increase gradually as the throttle plate is slowly opened from idle to wide open throttle. You can do this test with the engine off and the key on.
Where is the TPS located?
 
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Old 07-30-06, 02:27 PM
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Right there on the throttle body. Look for where the black plastic intake tube comes in from the air cleaner housing. Where it connects to the motor at is the throttle body. The TPS is on the exact opposite side of where the throttle cables attach. It will have a wiring harness connector on it.
 
  #9  
Old 07-30-06, 04:19 PM
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Originally Posted by Raynman
It was p1210 with the message I explained above.
Sorry for sound like an azz but.... I've try to look it up on my Dogde/Chrysler service manual but cannot find the "P1210" code to be able to give you what it said, instead of the "P0121" that's close to what you said but then again, it may not what you after and may leads you to replace unnessecery(sp) parts. I also aware of that you did explain it by what the AutoZone guy have said but I believed the "Factory" service manual has more detail of explaination on TDC than a "Generic" one.

Again, sorry.
 
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Old 07-30-06, 08:32 PM
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Originally Posted by New guy
Sorry for sound like an azz but.... I've try to look it up on my Dogde/Chrysler service manual but cannot find the "P1210" code to be able to give you what it said, instead of the "P0121" that's close to what you said but then again, it may not what you after and may leads you to replace unnessecery(sp) parts. I also aware of that you did explain it by what the AutoZone guy have said but I believed the "Factory" service manual has more detail of explaination on TDC than a "Generic" one.

Again, sorry.
My bad on the code. It is P0121. I went to the store today and when I got back in my jeep and started it the check engine light went off. Not sure what's up.
 
  #11  
Old 07-30-06, 08:33 PM
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Originally Posted by davzack
The possible causes according to Jeep for your DTC are:

-problem w/ harness or connectors
-TPS defective
-MAP defective
-PCM defective

The most likely cause is the TPS. To test the TPS you can use a digital volt meter. Backprobe the middle wire on the connector at the TPS and check voltage at idle and at wide open throttle. Voltage should be greater than .26 volts but less than .95 volts at idle. At wide open throttle, the voltage must be less than 4.49 volts. The voltage should increase gradually as the throttle plate is slowly opened from idle to wide open throttle. You can do this test with the engine off and the key on.
Check engine light is now off. By itself I might add. Not sure what to make of it.
 
  #12  
Old 07-31-06, 03:34 AM
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I'd check the vacuum hose that goes to MAP sensor. If the light is off and no driveability concern, I'd leave it.
 
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