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1999 Chrysler 300M Question: engine lopes, runs erratically, shifts erratically, rpm's up and down



bagley, 3.5L V6, Kingston, WA, December 01, 2009, 21:15

here's the problem...

1999 chrysler 300m running really rough. down shifting, up shifting erratically, rpm's all over the place wont stay running. what I have done is disconnect the positive battery terminal, hooked it back up to reprogram PCM, started the car, let idle to operating temp. held rpm's at 1200 for 2 minutes and drove around. seemed to drive fine but still have check engine light. I turn the car off and back on and it's back to running crappy. I hooked a scanner up to the onboard diagnostics and it gave me 2 codes...

P0123(M) Throttle position sensor input above the maximum acceptable voltage

P0121(M) TPS signal does not correlate to MAP sensor signal

scrolling down on my scanner it gave me 4 incomplete monitors and 3 ready monitors.

incomplete- catlyst, o2 sensr, o2 htr, EGR
ready- misfire, fuel, comp

I checked the voltage going to the TPS and it reads 5.0 volts, just like it should.
I checked the voltage going to the MAP and it reads 5.0 volts like it should.

PCM problems??? relay problems??? battery problems??? o2 sensors bad???
I don't have a clue. help

2 Answers
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  • Medium-star Best Answer
    December 01, 2009, 21:26

    Customer Concern: No start, no spark or injector pulse. Set codes P0121 and P0122. This started after engine work was done by another shop.
    Tests/Procedures: 1. Check the voltages at the Throttle Position Sensor (TPS). The Violet/White wire is the 5 volt power supply, the Orange/Blue wire is the signal and should have 5 volts when unplugged from the sensor. The last wire is the Black/Light Blue sensor ground wire, it should show less than 50 mV with the key-on.

    2. Make sure the TPS was not switched with the Crank Angle Sensor (CKP) as the connectors are similar.
    Potential Causes: Crank Angle Sensor (CKP)
    Throttle Position Sensor (TPS)

    Tech Tips: Crank Angle Sensor (CKP) connector was plugged into the TPS.

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    backyard tech, December 01, 2009, 21:28

    Vehicle Application: 1999 Chrysler 300M 3.5L 1999 Chrysler LHS 3.5L

    Customer Concern: Has a check engine light with codes P0123.
    Tests/Procedures: 1. Check the wiring at the Throttle Position Sensor (TPS).

    2. There are 3 wires, an Orange/Dark Blue, a Violet/White and a Black/Light Blue. With the sensor connected and the throttle closed the Orange/Dark Blue should read 0.6-0.8 volt, the Violet 5 volts and the Black/Light Blue under 50 Milivolts.

    3. If the voltage is high on the Black/Light Blue, the sensor ground has been lost, likely in the wiring harness splice.
    Potential Causes: Throttle Position Sensor (TPS)

    Diagnostic Codes: P0123

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    backyard tech, December 01, 2009, 21:30

    The voltage you were reading is reference voltage not signal return voltage. You have a bad TPS. What kind of scanner are you using?

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  • Answer #2

    Visitor, July 29, 2010, 19:04

    You need a new map sensor.Had the same problem.

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