mk2 digifant not starting

Discussion in '8-valve' started by SMc, May 29, 2018.

  1. SMC

    SMc New Member

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    Hi everyone i'm looking for some help if possible. My Mk2 golf is usually parked up over the winter. When summer time comes I get her going again, serviced etc.
    Last winter I removed the ecu, tci switch and battery for storage indoors. I refitted them, charged the battery and went to start the car. The car would just turn over without starting.
    Here's what I noted.
    -fuel pump not priming (suspected new pump, but when i bridged the pump relay the pump would run, I thought it must be the relay so I replaced that with a new one - this made no difference).
    -battery showing 12.4v so i assume its ok
    -on a visual check all earths and connections appear to be ok.
    -battery voltage shows on switch unit between pins 4 and 2.
    -i swapped the ecu for an old one that was blown (would make the pump run constant) but this made no difference and did not make pump run.
    -the idle valve is not buzzing with ignition on
    I'm suspecting that its to do with the wiring to the ecu as i'm not getting battery voltage at pins 13 and 14 with ignition on but i'm a little lost on where to start to rectify this.
    I do get cranking voltage between pins 1 and 13 during cranking, fuel pump doesn't run however if i bridge pins 3 and 13.

    Any suggestions greatly appreciated my Mk2 will be 30 years old on friday and i'm feeling really sorry for her!

    thanks
    Stephen
     
  2. Tristan Forum Junkie

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    Dodgy key switch?
     
  3. rubjonny

    rubjonny Administrator Admin

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    I take it dash electrics all powering up fine? does it or did it have an old alarm or immobiliser fitted? if so maybe ignition wirign needs checking over

    does the 53 relay in slot 1 click with ignition on? check fuse 17 if not, if thats ok try swapping the other 53 relay over see if that clicks.

    did you try jumping 3 and 13 with ignition on? if not, try that next.

    pull the plastic scuttle tray out and look at tghe 2 pin spade plugs near the wiper motor, these carry all fusebox signals to the ecu and are not sealed so you may have corrosion build up
     
  4. SMC

    SMc New Member

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    thanks guys, I'll hopefully check later and let you know.
     
  5. SMC

    SMc New Member

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    had another look this evening
    -ref dash lighting up, all seems to light up ok although indicator light is illuminated and indicators don't work (hazard lights work though!)
    -ecu relay clicks ok, fuse 17 ok
    -jumping pins 3 and 13 doesn't make fuel pump run
    -i checked the spade plugs behind scuttle, plugs looks clean and checked continuity either side (checked black/yellow wire continuity right back to green 2pin plug at the rear of the fusebox)
    -additionally i tested all earth connections at ecu plug, all ok.
    -also continuity between pin 3 of ecu and 85 on fuel pump relay socket is ok.

    main problem seems to be no battery voltage at pins 13 and 14 for the ecu relay, would i be right in saying if ecu got power then all other components should kick in like isv, fuel pump etc??

    thanks for your help
    Stephen
     
  6. rubjonny

    rubjonny Administrator Admin

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    check fuse 19 for indicators, hopefully 1 thing easily fixed :lol:

    ok so with the ignition on and 53 relay clicked, do you see power at plug R black/yellow wire? if not swap another relay into slot 1 you should have another 53 for the horn

    if you definitly have good earth on pin 13 back to battery and pin 3 has continuity to fusebox, yet no fuel pump with ignition on and these pins jumped then theres another issue going on here. does the fuel relay click with ignition on when you do this, 67/80/167 in slot 2? if so look for power at e/14, and look at fuse 5. you can bypass ecu control of the fuel pump entirely by swapping the 17 or 18 relay into slot 2, this should put fuel pumps on with ignition which can be helpfull for troubleshooting purposes.

    if the ecu sees voltage at pin 14 and earth at 13 it will buzz the isv, and will prime the fuel pump. there is another earth to the head on ecu pin 19, which might affect theres but you should still see fuel relay triger regardless if you earth pin 3 with ignition on. so whats odd here is you do seem to have ignition at the fusebox because the ecu relay does click, but if you earth the fuel relay pin 3 it still doesnt trigger the pump relay. so seems to be a couple unrelated issues...

    have a look for the brown wire with spade hanging out of the D plug, this should be earthed to the 4 way white spade block on the headlight loom, which is attached to the fat brown from the battery. there is another wire with spade on the back of the spade block which should go up to the earth claw as well. while there look around for any loose browns, generally if they have a brown or black spade housign they go to the spade block, if bare or have a clear spade housing they go to the claw. long shot since it was all fine when parked up and hasnt been messed with though...
     
  7. SMC

    SMc New Member

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    Thank you, I’ll try these things tomorrow if it’s dry!
     
  8. SMC

    SMc New Member

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    Hi just in from checking over things again, ref indicators fuse 19 is ok, when ignition is on the indicator symbol glows green, when indicator switch is operated it goes a brighter green but they don't work. Unplugging the hazard switch stops the indicator light glowing but they still don't work.

    Also horn doesn't work but here's the weird part, i put power to the plug at the horn and the fuel pump started to run! I checked the earth at the horn press on steering wheel for continuity and it was ok. Voltage at the horn press live was showing as a small amount of voltage so when i put 12v directly to the live at the horn press the relay would click, but when i put the terminals together there was a serious heat generated.Not sure what this means.

    This evening i looked at the earths in around the dash and the metal bracket clipped on up high behind the dash was quite corroded and the spade terminals onto it were in bad shape. I cleaned it all, fitted 4x new terminals but it made no difference.

    ignition on and 53 relay clicked, do you see power at plug R black/yellow wire? - with ignition on and 53 relay clicked no power at black yellow wire, swapping relay makes no difference.

    does the fuel relay click with ignition on when you do this, 67/80/167 in slot 2? - Jonny i'm sure what you mean here??

    not quite sure what to do next, I'm wondering should I remove and clean all earth contacts even though they look ok and they tested ok?
    Is it possible that the fusebox could be the cause of all the grief?

    thanks again for all your help I really appreciate it!
     
  9. rubjonny

    rubjonny Administrator Admin

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    It sounds to me like you have issues with power at the fusebox, it's a bit odd because you have enough ignition power to switch the ECU relay but not enough to power the indicators. But if the live feed was ok your ECU should still switch on if the relay got triggered...

    Have a look at the 2 fat red main live wires at the fusebox P spades. One is from the battery live terminal and the other goes up to the ignition switch pin 30. You should see good battery voltage at fusebox P spades, and on ignition switch pin 30.

    Next check ignition switch pin 15 black wires which are the ignition live feed back to the fusebox and the dash clocks. This should see good voltage ignition on. Chase the ignition switch wiring back to fusebox checking for damage or splices from old alarm/immobiliser modules

    Check the fusebox itself as well for damp and signs of corrosion or heat damage.

    I meant that if you leave the ECU pins 3 and 13 jumped and switch ignition on does fuel relay click as well as the ECU relay?
     
  10. SMC

    SMc New Member

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    Golf is up and running!!!
    As you suggested Jonny, when checking the black wire from back of ignition switch it was only showing 0.17v at the rear of the fuse box, at the switch end there was a connector in the wire and it was showing 12v at the other side of it. Put a new connector in and she started first turn of the key!

    Thank you Jonny for all of your help, I really appreciate it, I was getting to the point of despair!
     
    Spacecowboy likes this.
  11. rubjonny

    rubjonny Administrator Admin

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    good stuff :)
     

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