CCC - ALDL - Check Engine Light

Discussion in 'Troubleshooting & Diagnosis' started by KMcHale, Aug 25, 2019.

  1. KMcHale

    KMcHale Member

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    Finally got the paper clip stuck into positions 4 and 5 (the two to the far right) and got some codes. Found a link with the codes but wanted to double check to make sure I have the right definitions for the codes that I am getting:

    13: Oxygen sensor circuit open or no activity
    23: Intake air temp sensor error (low temp indicated)
    34: MAP sensor circuit error (signal low indicating high vacuum)

    These codes sound right? Also is there a way to clear these codes and see what comes back? I have been ignoring the light for several years because the car runs fine (for a 305).

    As always and help or guidance is greatly appreciated.
     
  2. BonzoHansen

    BonzoHansen Administrator Lifetime Gold Member

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    Disconnect the battery. That will clear the codes
     
  3. RickM

    RickM Veteran Member

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    This ^

    Clear the codes and then see if they come back. They could have been in there for a long time.
     
  4. KMcHale

    KMcHale Member

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    OK cleared the codes by disconnecting the battery. Reconnected the battery tried the paper clip thing to check for codes before I started the car again. Nothing not even the code 12. Started the car the light came on so I shut it off and did the paper clip thing. Now I only get the code 23. Troubling thing is that am I not supposed to get the 12 code 3 times and then the trouble code 3 times?
    and then back to the 12 code 3 times and then the 23 code 3 times and loop from there?
     
  5. RickM

    RickM Veteran Member

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    Yes, you should get the 12 code 3 times. If not something is wrong. Also, code 23 is for the mixture control solenoid not an air intake sensor (our cars don't have an air intake sensor). Look closely at the mixture control solenoid wiring and reseat the connector. More likely since it was the first code you found would be to check the o2 sensor wiring. If the o2 sensor has never been changed it probably is due to be changed. I would remove the computer and try reseating the prom in the computer. This will force you to reseat the computer connector cables. Also make sure the main (system) ground point for the computer is in good shape. It comes out of the computer harness and is attached to the engine block to the alternator bracket. You need that 12 code to make sure it is working correctly.

    RickM


    upload_2019-9-1_21-8-38.png
     
    Last edited: Sep 1, 2019
  6. KMcHale

    KMcHale Member

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    Replaced Oxygen Sensor. Now getting the following codes. According to my shop manual these are
    13: Oxygen Sensor Curcuit - The engine must run up to five minutes at part throttle, under load road, before this code will set. (Drove it more than 5 minutes)
    23: Open or grounded M/C solenoid circuit
    34: Manifold absolute pressure MAP or vacuum sensor
    45: Rich System indication - the engine must run up to five minutes, in closed loop at part throttle and road load before this code will set.

    No code 12!

    Going to remove the computer and re-seat the PAM and see what happens.

    Rick M: A little confused by the "It comes out of the computer harness and is attached to the engine block to the alternator bracket." Any chance you can clarify.

    BTW: Car runs fine when I start it I turn the key to the on position then floor the pedal the air induction opens right up. I start the car wait for it to warm up. Runs at slightly 1000 RPM's I blip the gas and it drops down to 600 RPM's. When I turn on the climate control on the RPM's just up so the computer is doing it's job.
     
  7. RickM

    RickM Veteran Member

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    From the picture below. The ECM ground is attached to the alternator bracket and is bolted to block. This is critical for the ECM to operate properly.

    Hope this helps
    RickM

    upload_2019-9-9_19-7-0.png
     
  8. SRGN

    SRGN Veteran Member

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    As stated above, check the grounds. I believe that one may also have a ground at the thermostat housing and at the back of the cylinder head. I'm getting older and can't remember like I used to.
     
  9. RickM

    RickM Veteran Member

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    Also how are you getting the codes?

    You must have the key on (Run position) and the engine must NOT be running.

    Then ground jumper pins 4 & 5 and leave them jumped.

    This should get you 3 code 12's followed by any stored codes.

    RickM
     
  10. Vettenick

    Vettenick Vettenick

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    You need to get your hands on a scan tool to read the computer data so you can see what the sensors are doing. Trying to fix this thing by reading codes is a waste of time and money. It seems to run fine because it running rich. After a few minutes the computer is trying to compensate, and it can't, probably to the the mixture control solenoid being stuck open or inoperative. You will be able to determine that with a scan tool that reads data. If you get one, just post what the data reads, and I will walk you through it.
     

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