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Check Engine Light (All of a Sudden)

Discussion in 'Minivans · Pacifica' started by slim slow slider, Nov 7, 2017.

  1. slim slow slider

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    I changed out the TPS on my 89 Caravan with the 2.5 four cylinder engine. Started and drove the van and noticed the CEL. Perhaps because of the new part?

    I was told to disconnect the negative battery cable to reset the computer.

    Is this what I should do?

    All functions working correctly. Gauges show great amps; plenty of gas, great oil pressure.

    Suggestions appreciated!
     
  2. CudaPete

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    And the code is.........
     
  3. slim slow slider

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    How do I do that??
     
  4. CudaPete

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    Use the key dance. Cycle the key on/off, on/off, on without starting the car and count the number of flashes from the CEL. This will correspond to a code.
     
  5. Bob Lincoln

    Bob Lincoln "CHECK FAULT CODES"
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  6. slim slow slider

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    Gotcha! Thanks!
     
  7. slim slow slider

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    Code 24

    How do I correct it??
     
  8. Bob Lincoln

    Bob Lincoln "CHECK FAULT CODES"
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    That's for the TPS. It may have been stored when the previous one was faulty or unplugged with the key on. Disconnect the battery for several minutes, and the only codes should then be 12 and 55.
     
  9. slim slow slider

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    Looks like I put the plug in backwards. Put in correctly. Now get Code 12 and 14. That 'Check Engine Light' really bugs me. As long as it's not doing damage, I'll drive it like this for while. Need to take trip shortly. Disconnected negative battery cable for about 5 minutes. Re-connected. CEL still on. Leave cable off longer????
     
  10. Doug D

    Doug D Virginia Gentleman

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    If memory serves, I think you have to leave the cable disconnected about an hour or so.
     
  11. AllanC

    AllanC Well-Known Member

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    In all of my experiences with Chrysler vehicles with OBD I electronic engine management, interrupting battery power for just a few seconds was sufficient to clear any diagnostic codes. You do NOT need to leave battery cables disconnected for hours to clear codes.

    Code 14 indicates MAP sensor voltage out of range: too low or too high. This is a guess on my part and I hope I am wrong but I believe connecting the wiring harness with the TPS plug rotated 180 degrees could have damaged either the MAP sensor or the driver circuit for the MAP sensor in the PCM (powertrain control module). Look at attached schematic for the engine controller (PCM) pinouts.

    (NOTE: pinouts assuming engine is 2.5 liter, NON-Turbo engine)

    Cavity 1-13 I believe is a regulated 8 volt source for the throttle position sensor and MAP sensor. When you switched the plug 8 volts was sent through the throttle position sensor to the DK GRN/RED wire which connects back to cavity 1-1 at the PCM and MAP sensor. This is the MAP sensor signal to the PCM. This higher voltage could have damaged the MAP sensor or the driver circuit in the PCM. Again this is a theory so I I invite others to comment.

    You could replace the MAP sensor and see if the code 14 disappears. But MAP sensors are not inexpensive. And if the driver circuit for the MAP sensor in the PCM was damaged, the only remedy is to replace the PCM. Again that is not an inexpensive item. And I most certainly not advocating firing the parts cannon at a fix but I am not sure if there is an easy and definable way to check the MAP sensor and its circuitry to the PCM.

    PCM Pinouts2.gif
     
    Bob Lincoln likes this.
  12. ImperialCrown

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    The TPS connector is keyed to only plug-in one way unless the plastic keyway is broken?

    Code 12 is likely from disconnecting the battery neg cable to erase the code 24. It shouldn't light the 'ck eng' light, but will stay in PCM memory for the next 30-40 starts.

    Code 14 will light the 'ck eng' light and may cause rough running. It is a missing or impossible MAP 'electrical' value, not MAP 'vacuum' fault. Could be the MAP sensor or wiring or PCM at fault. The PCM will insert a default MAP calculation that will substitute an approximate value if the MAP signal is unbelievable.
    Chrysler ECU Computer Code 14 (at https://www.allpar.com/fix/codes/faults/code14.html )

    Make sure that the sensor is getting a 5 or 8 volt supply and has a good ground. The MAP signal wire voltage should vary with with the intake manifold vacuum.

    If a fault code comes back after disconnecting the battery, it is likely a real code.
     
  13. slim slow slider

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    Walt: I can change out the MAP sensor tonite. Was hoping to leave tomorrow for a must-do trip from Arizona to Nevada.
    After turning the plug around (plug into the TSP), van ran fine for awhile. Took out today and long standing problem occurred. Loss of power,constant surging, not able to travel more than 35 MPH. Limped home, started van after 2 hours, can see tach not remaining steady @ 900 RPM, fluctuating back and forth between 1K and 1100RPM.

    Some time ago, there was an issue with wiring getting hot. Had a fusible link go back; sorry to say, never replaced it. Have no idea why certain section of wiring harness gets hot. It is a portion that connects to the TB. Just replaced the fuel pump and TPS. Will replace the MAP senor tonite. I also installed new pressure regular a while back. Maybe 2K miles ago.

    Walt: I need dependable transportation. At 75 years old, I cannot get stranded on a lonely highway with no cellphone service! This 89 Caravan has been nothing but trouble.

    I have that 87 Voyager with a 2.2 carb engine that runs. I will have to press that into service because I cannot be without basic transportation. I live in a rural area in Central Arizona. I need to get to rural NE Nevada as soon as possible.

    If things do not correct themselves with replacement of MAP sensor, must make this trip in that 2.2 carb Voyager. It really needs the carb adjusted, but I drove it 360 RT miles without any trouble. It seems to me the carb choke needs to be adjusted. The carb is BRAND NEW. Holley 5220. Bought on E(vil)Bay. Sometimes have trouble starting because butterfly closes, thereby preventing smooth start. Trying to find anyone nowadays who knows anything about these carbs is getting harder and harder. Even if I got to my destination, there is no one who could help me. Pity!


    Thank You so much for being helpful. Hope this will correct the problem. (For good)

    Regards,

    Mike Allen
     
  14. Doug D

    Doug D Virginia Gentleman

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    Before replacing the MAP sensor, it would be a good idea to check the vacum line connecting the MAP to the throttle body. Long ago I had work done (timing belt) on my Acclaim (same engine 2.5L) and the tech had disrupted the line causing similar symptoms - high idle, surging, and CEL. Once I secured the connections and checked for cracks/cut line (there were none), it went back to normal and the CEL was off.
     
  15. ImperialCrown

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    The wiring harness that runs behind the valve cover gets cooked from exhaust manifold heat after a few years. I have had the plastic wire insulation crumble apart as soon as I disturbed the wiring (while pushing it out of the way).
    Bare wires can short to ground. Wrapping them in tape may short them together.
    How does the harness look back there?
    An EFI vehicle would be preferable to a carburetor on a long trip if it can be repaired to run right.
    A brand new Holley 5220 is still 30 years old.
    Best of luck and make your vehicle choice for the better running one.
     
  16. slim slow slider

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    Some of that wiring was replaced some time ago, back in '15. There were melted wires back there that needed to be replaced. Nothing appears odd back there now. I must find some tape which claims to deflect heat away from wiring and certain metal lines to correct vapor lock.
    Installed MAP sensor from an 89 3.0 engine. Ran rough after starting, died twice. CEL still on.

    Started twice more, engine seems to smooth out. Idle is low, about 800 RPM. This is about right for these engines. Taking out for a test drive.
    Am I out of the woods yet??
     
  17. Bob Lincoln

    Bob Lincoln "CHECK FAULT CODES"
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    Don't leave that MAP sensor in there for long. It may have a different output curve for the air-fuel mixture, and running the engine too rich or lean can cause damage.
     
  18. slim slow slider

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    Part #'s between the 2.5 and the 3.0 are different on the original Mopar sensors.

    However, Rock Auto shows the same sensor for both cars. Not two different sensors.
    What should I do??
     
  19. Bob Lincoln

    Bob Lincoln "CHECK FAULT CODES"
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    They may be the same, or they may be very close. Out of caution, I'd install the correct one for the 2.5L before too long. Should be OK in the short run if you don't see signs of running very rich (black smoke, chugging) or very lean (running hot, lack of power).
     
  20. slim slow slider

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    OK, will replace. Thanks Bob!
     

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