Pulling codes on a OBD2 (1996) 1uz without diag. port.

Discussion in 'Diagnostic & Repair Tech' started by yontzie, May 11, 2017.

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  1. yontzie

    yontzie New Member

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    Hello,

    I have a 1996 OBD2 1UZ in a Nissan 240sx. Ive got the thing up and running and id like to pull the codes. I cant seem to find any information about pulling codes on an OBD2 without using a scan tool. Is there a way to do this without a scan tool? So Far i have tried grounding the T1 wire (Pin #5 on the 16 Pin connector[red/black wire]) hoping that it would flash the codes out on the check engine light. but the check engine light just stayed illuminated.

    Would one of these 22 pin adapters work with the diagnostic port on the engine to pull the codes..?
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    Any ideas?? Thanks in advance!
     
    Last edited: May 11, 2017
  2. gloverman

    gloverman Active Member

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    Have you considered wiring the diagnostic port?

    Does the CEL illuminate when you turn the key on? Then go out once the engine starts?

    Grounding the T1 (Te1) should allow the ECU to flash the CEL if it's wired correctly. If it's not doing so possible issues are the ECU is stuffed or there is a wiring issue.

    The engine bay diagnostic plug doesn't always have all the required wires to allow a scanner to communicate. When I wire them I always modify the wiring to that diagnostic box so scanners can talk to it and I have an adaptor for the underdash connector too. The engine bay connector doesn't always have clear info ie the engine temp is displayed as a voltage on some scanners.
     
  3. yontzie

    yontzie New Member

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    Yes the CEL illuminates when i turn the key on. When I start the engine the CEL stays illuminated. ( i have deleted the EGR so i believe it should always stay on when the engine is running)

    In the Diagnostic port on the engine, it is missing the Te1 wire. So I spliced a wire into the Pin #5 on the 16 Pin connector[red/black wire] located right at the ECU and grounded that instead of jumping pins on the diag. port on the engine to hopefully pull the codes via the check engine light.
    The wiring harness is completely un-cut. EGR clip is still there, its just unplugged. Because it is a 1996 (OBD2) Is it even possible to pull codes via the flashing check engine light or can you only pull codes on an OBD2 using a code reader..?

    Ive read somewhere that the car needs to be in Neutral to be able to pull the codes. Im using a manual box with an adapter plate so I cant put it in neutral. Would there be a way of tricking the computer into thinking it is in neutral? might this be the problem?
     
    Last edited: May 12, 2017
  4. gloverman

    gloverman Active Member

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    Every one of these I have wired I have always been able to pull codes manually. I always check manually and with a scanner on the bench before the loom goes out. And I have wired a number of US and canada imports. Both Manual and Auto setups.

    Ive found some that had issues retrieving codes when they came in. I had to fix lots of wiring issues and many ECU's. Ive also had phantom codes when there are wiring issues.

    Does your engine idle up nicely when cold then drop slowly to a low hot idle?
     
  5. yontzie

    yontzie New Member

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    No it does not. I can get it started but it has a rather low idle. and doesn't really drop anymore when it warms up. Im guessing there is a code that is causing this. Im not sure why it wont flash when I ground out T1. Ill try to locate a spare ECU and give that a go
     
  6. gloverman

    gloverman Active Member

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    I would guess it could be an ECU or it's wired wrong. One good way to check is to put a test light into pin A28. Key on the light should be on , Start the engine then after 20 seconds of running turn the engine off. Tell me if the light stays on for about 4 seconds or turns off straight away. Then complete the same test at the IAC(unplugged to test is fine, one of the centre pins)
     
  7. yontzie

    yontzie New Member

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    Where is pin A28 located, I have searched but cant come up with anything...

    Thanks again!
     
  8. gloverman

    gloverman Active Member

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    ECU plugs are A,B,C,D. 28 pin plug is A plug. Sorry I meant A22.(A28 is overdrive (3) Switch) This is the lower right hand pin. Labeled as +B on diagrams.
     

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