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Motronic 1.3 ECU

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    Motronic 1.3 ECU

    So, I've been troubleshooting a no start/no crank issue all this weekend on my manual 1987 325i and I'm stumped. The last thing I can think to check is the ECU. Anyone in the Portland area got a known good Motronic 1.3 ECU I could borrow? I live in Aloha, so the closer the better.

    The car currently has a Bosch 0 261 200 525, but I understand any 1.3 will work, is this correct?

    I've read novels worth of forum post looking for things to test, but as I said, I've run out of ideas. In case anyone has any pointers I'll throw up a list of everything I've tested:
    1. Battery
    2. Original Starter and known working starter (tested both starters out of the car and they both function properly.
    3. Ignition ON/START wire (12v)
    4. Ignition Switch - passed all continuity test (see comments below)
    5. Crankshaft Position Sensor
    6. Fuel Pump
    7. Relays
    8. Fuses
    9. ECU connector - passed all continuity and voltage test
    10. Ground Tests

    Also, every electronic in the car appears to function properly when the key is in the ON position: windows, radio, lights, etc. There is not dimming of the lights when I turn the ignition to the START position.


    One question about the Ignition Switch test that I've been unable to get an answer to, is... When I performed the "Start only" test between C1 & C there was continuity when I first begin turning the key, but once I reach the full START position there is no longer continuity. Is this how it normally functions or should it maintain continuity? I've been looking at my cars wiring diagram and I can't figure out what C1 and C are for. The wires are BROWN and BROWN w/ LIGHT BLUE STRIPE.


    From Bentley Service Manual, pg. 520.

    #2
    Is the ecu getting power? Is it grounded out or just laying in the glove box?

    When did this problem occur? After working on it? Or just out of the blue

    Comment


      #3
      Thanks for following up. I managed to get the car working again last night. Ended up being a grounding issue, but I'm still a little baffled because I did nothing to the car before it had the issue.

      http://www.r3vlimited.com/board/showthread.php?t=339191

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