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B16 CRX throwing code 6

Discussion in 'HYBRID -> ED-EF / DA' started by craftymatt, Jan 13, 2008.

  1. craftymatt

    craftymatt New Member

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    Swapped a B16a into a 91 CRX HF; OBD0 PR3 ECU

    Anyway, I'm getting code 6 from the ECU (Defective Coolant temp circuit/sensor), and I can't figure out why. The sensor is plugged in, I've tried swapping the sensor (and tested the resistance of both sensors, they were the same), and I traced the connector pins back to ECU/ground. The car runs okay but is obviously in limp mode (bad idle, 7200rpm rev limit, no VTEC etc).
    If I use the old HF ECU (PM8) it does NOT throw the code and runs much better (indicating that it is reading the ECT correctly).
    I've searched around to see if maybe on some of the PR3's the coolant temp sensor came in on a different pin, but that doesn't seem to be the case. Why else would this happen? Bad ECU? ECU code is 37820-PR3-003, is 003 some weird revision or something? I opened the ECU up and nothing appears to be damaged/modified.
     
  2. LS_VTEC

    LS_VTEC you get the BRAKE

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    Is the sensor bad? Did you test for resistance in the circuit itself? Is there sufficient coolant in the engine?
     
  3. CRX18703

    CRX18703 CT'sFinest

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    Its probably a lose ground, i had the same problem with minds
     
  4. riceburner89

    riceburner89 Banned

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  5. LS_VTEC

    LS_VTEC you get the BRAKE

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    The thermostat wouldn't cause a code-6, it just opens when the coolant reaches a specific temperature.
     
  6. craftymatt

    craftymatt New Member

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    figured it out!!!

    Turns out on the HF there is a wire coming into the ECU (B9 on the ECU connector) that tells the ECU when the car is in reverse. Every time I went into reverse (which happened to be every time since I had to back out of the driveway when I wanted to drive it) it would apparently freak out the ECU and it would trigger a code 6. This also explains why the HF ECU didn't have a problem.

    Anyway, I pulled B9 from the connector and now the car runs great. Finally I can hit VTEC!!!
     
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