OBD2 Issues with Smog Check on 2006 Prius

Discussion in 'Gen 2 Prius Technical Discussion' started by ShahGAutos, Feb 22, 2021.

  1. ShahGAutos

    ShahGAutos Junior Member

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    I’m need of help!! I live in California and I’m due for a biannual Smog to renew my registration. I’ve taken the prius to two Smog shops and as soon as they hook up the smog machine to run the test the car throws a check engine light and the Red triangle and VSC lights all come on. Codes state it has lost connection with the hybrid system (p1000). I have to reset it everything to get it driving again and everything is works fine. All monitors are ready and no warnings till we try connecting the Smog machine again. Not sure what’s going on. If it’s a computer issue or something wrong with the actual OBD2 connection. When I connect my scanner I have to mess with it before it can make a good connection. Any help would be greatly appreciated with this issue!! Thank you all in advance!
     
  2. PriusCamper

    PriusCamper Senior Member

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    I'd call around and see if you can find a shop that will troubleshoot connection errors between vehicle and smog test machine rather than just give up on it. Have not read of this problem before, but keep doing internet searches so you have as much info as possible when you call around to find someone to help you deal with this.
     
  3. ShahGAutos

    ShahGAutos Junior Member

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    Thank you for the response. I am calling everyone from the shop that replaced my hybrid battery in June to my regular mechanic shop and posting on FB prius groups. I think when this happened it thru a U0293 code. Researching the code now and it can be the 12v battery, the HEV fuse, or the actually computer or wires going into the computer. The fuse was fine but looked like it had corrosion on it...bunch of white stuff so maybe I’ll replace just for the hell of it. Then I need to check the 12V battery reading. I’ll throw it in maintenance mode and see what it says. Battery shop will check it under warranty next Monday. My regular mechanic is slammed so told me to call back on March 8th to see if they have openings for them to do diagnostic stuff to it. I’m trying my best not to give up on it since I’ve invested so much into making a reliable daily driver. Thanks again for the the encouragement I truly appreciate it!
     
  4. PriusCamper

    PriusCamper Senior Member

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    Checking your OBD2 pins for damage or corrosion would be wise... And if you can walk us through the details of how the warning lights come on as you set up your OBD2 and with which app, that might help some of the smarter folks on here help you diagnose.
     
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  5. ShahGAutos

    ShahGAutos Junior Member

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    I’ve attached pictures of the terminal and they look fine to me. I have another gen2 prius and compared it and they both look identical as far as condition is concerned.

    I did just check my 12v battery and it’s reading at 11.9v with the car off. Once I get it started it jumps to 14.0v for a quick second and then drops to 13.9v and is holding.

    The issue seems to only occur when the smog shops connect their scanners to run the test. As soon as it gets plugged in it turns on the red triangle, the check engine light, vsc light, and I can hear the engine’s fan running. I can only get my car back to normal by reset the check engine light with the scanner. My car drives a performs fine afterwards.
     

    Attached Files:

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  6. Elektroingenieur

    Elektroingenieur Senior Member

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    Since you’ve tried two different Smog Check stations, each having BAR-OIS test equipment that presumably works with other vehicles, I expect the trouble is in the car. No Prius model is on BAR’s list of Vehicles of Interest that are known to fail due to OBD II implementation problems, so I expect it’s more likely to be a wiring, connector, or ECU hardware problem than a software malfunction.

    On second-generation Prius cars, the same CAN bus that connects the ECM to the hybrid vehicle control ECU is also exposed directly at the DLC3 (OBD II) diagnostic connector. I imagine the symptoms you describe could be caused by the CAN bus lines being shorted to ground, battery, or each other, when an intermittent fault is triggered when something is plugged in to the DLC3 connector.

    The Repair Manual (more info), under Engine/Hybrid System: P112 Hybrid Vehicle Control: Hybrid Control System: Diagnosis System, has a table of voltage and resistance measurements at the DLC3 connector. If you have a multimeter, you could check these—but be careful to avoid deforming the terminals by jamming meter probes into them. Also, try wiggling the DLC3 connector and see if the measurements change.

    The Repair Manual also provides some step-by-step procedures for checking the entire CAN bus. Under Power Source/Network: CAN Communication: CAN Communication System, see especially the topics CAN Bus Line, Open in CAN Main Wire, Short in CAN Bus Lines, Short to B+ in CAN Bus Line, and Short to GND in CAN Bus Line.
    The test of terminals isn’t whether they look OK, but whether they make good contact with inserted pins. That can be difficult to check without a terminal gauge of the correct thickness (0.80 or 0.82 mm, per SAE J1962).
     
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  7. Raytheeagle

    Raytheeagle Senior Member

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    @Mendel Leisk had a similar problem with his Gen3 when he left the scan gauge plugged into the OBD2 port all the time.

    I forget the resolution (or if they had to fix the obd2 connection, but I know he doesn't leave the scan gauge plugged in anymore;).

    He'll be along eventually and usually offers his advice or how his situation was sorted:).

    Good luck and keep us posted(y).
     
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  8. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

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    Yeah I just left the SG disconnected, no further problems. Haven’t bothered with repair.
     
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  9. ShahGAutos

    ShahGAutos Junior Member

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    Thank you so much for taking the time to write out such a detailed response and helping me. I’ll attempt to show my mechanic this as they would have better knowledge when it comes to this stuff. I sadly wouldn’t know how to even start using a multi meter (not saying I could learn) just very limited on time and bunch of other life things going on on top of this. But I don’t want to sound like this was useless because this is invaluable information. Thank you again for being so kind to taking the time to help me!
     
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  10. ShahGAutos

    ShahGAutos Junior Member

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    I don’t have anything plugged into the OBD port for an extended period of time, but I did you a Bluetooth scanner to run the Dr.Prius app to diagnose issues I had here and there with the cars. Not sure how that could have messed up the connection. I’m glad your car was fixed easily! I’m hoping for the same outcome! I wish the smog would go smoother. Added stress for no reason
     
  11. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

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    Yeah my SG was constantly plugged in, more trouble prone I think.
     
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  12. mr_guy_mann

    mr_guy_mann Active Member

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    +2 to damaged / loose terminals in the OBD2 connector. You shouldn't have to fiddle with anything to "get a good connection". As suggested, you need a single male terminal of the correct size to check the fit- there should be some drag when inserted and removed. if one is loose you will feel it.

    Posted via the PriusChat mobile app.
     
  13. ShahGAutos

    ShahGAutos Junior Member

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    So I’ve officially smogged my car today! Thank god! I took it to my mechanic and he noticed that two pins in the OBD port were loose. He tightened them up and tried the Techstream and all the computer showed up properly. I then took it the third smog place and they were able to connect and run through the whole test with no issues! Good for another 2 years! Thank you everyone for your help and guiding me to the solution!! Huge relief!
     
    #13 ShahGAutos, Mar 22, 2021
    Last edited by a moderator: Mar 23, 2021
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