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I have had a problem that had stumped me consistently. I have a 2005 sebring that has been intermittently going into limp mode. I checked the code and it told me the tranny control module power relay circuit was always on when tested before start. I ended up replacing the solenoid pack and computer which made the problem go away for about 200 miles. It came back. When I inspected the circuit I noted that it had only a few points at which it was used: solenoid pack, relay, and 3 pins on the computer. enter image description here

When the car starts it uses these three inputs to test for voltage. If it is present the car does not activate the solenoid and goes into limp mode. If it is 0v then the car activates the relay and shifts properly...

My question, is it possible that these three test circuits could be feeding current from a leaky diode or something of the likes? Is it very well possible that the computer was not designed properly or damaged? Should I have a diode before each of these 3 inputs to the computer? What could cause these test circuits to be receiving power if it is not from the solenoid, relay, or wiring shirt?see pins 19 28 38enter image description here

enter image description here

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  • Each of the three ecu inputs are test circuits. When I test the circuit from the ecu connector there is no voltage. Could the test circuits be responsible?
    – Justin
    Commented Feb 25, 2020 at 1:04
  • Sedan 2.4 vin j code p0891
    – Justin
    Commented Feb 25, 2020 at 19:23
  • How are you testing for voltage? Do you remove the harness and check it at the pin of the pcm or are you just removeing the relay and/or selnoid?
    – narkeleptk
    Commented Feb 25, 2020 at 20:16

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is it possible that these three test circuits could be feeding current from a leaky diode or somethin

Yes, your pcm could have a component bad inside but it may just be from finicky software as well. You may could fix the issue by simply updating the calibrations(programming) in the pcm. I would look too see if there are any TSB's related to this issue and if so I would first try to have the pcm re-flashed

Is it very well possible that the computer was not designed properly or damaged?

If this is the NGC unit, they have common failures of the main mcu and/or its soldering (its bga chips so not easy to rework).

Should I have a diode before each of these 3 inputs to the computer? What could cause these test circuits to be receiving power if it is not from the solenoid, relay, or wiring shirt?

There are many components in the circuit for this control inside the pcm. Most are passive type and not prone to failure and if they did it would more likely be a open circuit fault or consistent hi/lo signal.

You said you replaced the computer already, why would you still suspect it? Sounds more like it may be somewhere else that your missing.

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  • Code p0891 2.4L vin J
    – Justin
    Commented Feb 25, 2020 at 19:20
  • The circuits responsible I drew a diagram representing it. Just a single wire from solenoid pack to fusebox in middle it has 3 wires from a junction to the ecu
    – Justin
    Commented Feb 25, 2020 at 19:22

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