OBD1 VR6 Query

Discussion in 'Electrical' started by that_black_cab, Jul 12, 2019.

  1. that_black_cab New Member

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    Hi guys. Some wiring help if possible - this one is a head scratcher! I’ll start from the beginning - obd1 distributor mk3 and this was/is a running conversion that has been done for 18 months or so but has always had some kangarooing issues under load and intermittent poor idle that I could never pin down. I have replaced EVERY sensor, distributor and related parts etc, had the ecu tested with a full report so I’ve started to go through the wiring. I’m looking specifically at the ecu plug itself...now, a majority of wires match all the information I can find from a2 resource and the Bentley manual...it’s the last row of wires - from 48 onwards which appear to be in the wrong location at the ecu but the colours go to the right places (sensors and earths) which is puzzling to say the least. My gut says to swap pins at the ecu plug but I’m apprehensive as it’s not something normally done. I will attach the photos below for you to peruse and I’m hoping someone can shed some light and save me from never ending misery.

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  2. rubjonny

    rubjonny Administrator Admin

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    Location:
    Bracknell
    A2 resource doesn't cover early distributor engines so will differ slightly to your ECU. Your pins look fine to me but heres a pinout list I put together for pre-93 with distributor:
    1 - earth
    2 - fuel injector 6 pin 2
    3 - fuel injector 2 pin 2
    4 - fuel injector 4 pin 2
    6 - fuel pump relay trigger
    7 - earth (manual) to automatic transmission system (auto)
    8 - ignition coil pin 2
    9 - ecu relay earth
    11 - automatic models
    14 - clt pin 2
    15 - unused?
    16 - MAF pin 2
    17 - MAF pin 3
    18 - automatic models
    20 - lambda pin 4 (signal live)
    21 - diagnostics L line
    22 - rev counter feed to dash
    23 - ecu relay live feed
    24 - fuel injector 1 pin 2
    25 - fuel injector 5 pin 2
    26 - fuel injector 3 pin 2
    27 - isv pin 1
    28 - lambda heater control relay
    31 - carbon canister pin 1
    33 - knock sensor 1 & 2 pin 2, clt pin 1, iat pin 2, tps pin 2 (sensor earth)
    34 - knock sensor 1 pin 1
    36 - iat pin 1
    37 - aircon
    38 - ignition live feed
    39 - aircon
    40 - tps pin 1
    41 - tps pin 3
    42 - lambda pin 3 (signal earth)
    43 - diagnostics K line
    44 - hall sender pin 2
    51 - mpg feed to dash
    53 - isv pin 2
    54 - permanent live feed
    55 - earth
    56 - earth
    57 - knock sensor 2 pin 1
    58 - earth (automatic transmission only)
    59 - MAF pin 4
    65 - speedo signal from dash
    67 - crank sensor pin 1
    68 - crank sensor pin 2
     
  3. rubjonny

    rubjonny Administrator Admin

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    I take it no fault codes are logged and you've been through the ECU measuring blocks to make sure all sensors are reading ok? You can get vagcom to log the output from a group of measuring blocks too which is useful for intermittent faults such as this
     
  4. that_black_cab New Member

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    Many thanks for the swift reply. Absolutely fantastic pin out diagram, helps me no end! I have tried vagcom but it doesn’t communicate (interestingly I can’t get it communicate with my standard mk3 tdi either) so I suspect that I have a problem with the k line but I haven’t delved in too deep just yet. Because I had incorrect information (thank god!) I was genuinely concerned that the ecu had been fried etc so this was my starting point. Now I know that it is ‘OK’ I will crack on and dig into it.
     

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