Fusebox FAQ

Discussion in 'Electrical' started by rubjonny, Jul 30, 2010.

  1. rubjonny

    rubjonny Administrator Admin

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    hello there, there is a lock tab which is on the right side and goes across the middle of the fusebox to hold that rear plug tab in place. click it to the right to release :)
     
  2. Smithdog84 New Member

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    thanks mate what a plonker. did not hide that when I took them out.
    Also I have a cable coming from my obd port which is an Earth with a spade on. where would be best to connect this in t. Fuse box ce2.
    thanks again mate.
     
  3. jimmy2gti New Member

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    Hello guys
    Trying to sort the electrical system lately. CE1 1984 MK2 gti, with mfa, consumption, upshift etc.
    Question 1
    There is a plug that is hanging on the rear of the fusebox, i tried to track it down and only found that a green/white cable is going to a plug on the transmission housing. Not quite sure what its purpose is.

    20200417_232532.jpg

    Question 2
    The whole system is acting up and i tracked a possible fault to be at relay pos. 8. I have a no 17 relay there, my friend has a spare no 18 relay at this position, they're essentially the same part number but his has an extra resistor inside the circuit. Can i use his without problems?

    Jim
     
  4. rubjonny

    rubjonny Administrator Admin

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    1. You should have a red/black wire from C/18 plugged into the left side of that plug, the green/white wire side is left empty on UK spec.

    2. Yep you can use an 18 relay or 100 in that slot
     
    jimmy2gti likes this.
  5. Freakum86 New Member

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    Ok. Been sat in the car for hours reading these threads. But I’ve signed up to ask a question fuse box related because I am just testing at it now and have found that several of the fuses in the fuse box including number 5 fuel pump have no power. As in on either side of blade fuses is this normal.
    I’m looking here because my car won’t run and I have found the pump isn’t getting power. But relay works when I energise directly off the battery
     
  6. rubjonny

    rubjonny Administrator Admin

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    Hello and welcome :)
    what type of fusebox is it and which fuses apart from 5 are not powering up? what engine do you have as well
     
  7. Freakum86 New Member

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    Thanks for replying Jonny not sure on engine fuse box is ce1. Car is a 1990 golf cabriolet think the car is the knee type fuel injector system as has the braided fuel lines to each cylinder. I’ll have to go check the fuse box again.
     
  8. rubjonny

    rubjonny Administrator Admin

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    ok 90 cab is a CE1 fusebox, let me know which other fuses are not powered.

    so fuse 5 is the main one which is fuel pump, this is powered by the fuel relay in slot 2 and is triggered by the rev counter signal from the coil. first off what type of relay have you go there, and when cranking on the starter motor does your rev counter jiggle?

    you can bypass the relay for testing if you switch the x-relief relay in slot 8 directly below into slot 2 which will make the fuel pump come on with ignition. if the car runs like thischeck the rev counter works, if not theres the problem. if it does the relay may be incorrect or bad
     
  9. Freakum86 New Member

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    Ok never thought to swap relays. I do get a 12v feed from coil the red and black wire and the relay works when powered from the battery directly my understanding so far was that the small pin should become live and bring relay on. But nothing. If I power the relay the small pin becomes live.
     
  10. rubjonny

    rubjonny Administrator Admin

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    the kjet relay needs an earth pulse from the coil negative on the small pin to trigger, this is how it knows engine is running. if you dont have a spark for whatever reason then you wont get fuel either. swapping the X relay over will tell you if issue is down to fuel relay or not anyway
     
  11. Freakum86 New Member

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  12. rubjonny

    rubjonny Administrator Admin

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    fusebox looks pretty good, correct relays all round. have a good look for corrosion etc but from what I can see looks alright
     
  13. Freakum86 New Member

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    I took the fuse box apart. Removed the outer plastic casing. And their was a bit of corrosion at the bottom around circuit 5 but following the wiring diagram in Jain manual I get continuity around all the proper pins.
    I’ve swapped relays as said and as before I get an initial rumble as the engine starts but nothing after
     
  14. rubjonny

    rubjonny Administrator Admin

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    ok if you get fuel pump and a brief start this suggests fusebox is ok, did you notice any life from rev counter?

    need to go back over the engien side now I recon to figure out why it wont stay running, give ignition system a service buff up all the battery cabling, check any cables on head/battery are nice and clean etc
     
  15. Freakum86 New Member

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    Yeah so I started that cleaned up a few corroded and dirty earths. I check rev counter later as I need to go out now Jonny did you see the other post from magic they have similar issues and started the same day. I tagged you in post.
     
  16. Freakum86 New Member

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    Ok yes to life from rev counter flickered upto 10k then engine died
     
  17. Freakum86 New Member

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    Sorry I need to read the advice thoroughly. Ok so no the fuel pump doesn’t kick in. The relay works When I test it at the battery but doesn’t seem to switch on when I start the car. I found a loose earth strap on the head that links to the coil. Have cleaned up all the connections In the engine I can see.

    fuses in fuse box ignition off 1-4 live 12v
    Ignition on 11-19 on.
    Rest off no power
     
    Last edited: Apr 27, 2020
  18. Freakum86 New Member

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    https://photos.app.goo.gl/V6riRGftCjtHe38M8

    So this is what I’m working to. I follow the wires from the pump back to the fuse box through the relay to the fuse. But where does the feed to the fuse come from. What are the top lines 30.15.x.31 and the bottom ones 15.16 blank
     
  19. rubjonny

    rubjonny Administrator Admin

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    for understanding VW diagrams, start here :)
    https://www.clubgti.com/forums/index.php?threads/how-to-read-vw-wiring-diagrams.173722/

    the fuel relay gets live from inside the fusebox, main 'P' spade from fusebox gives the fusebox live on the '30' rail, it has ignition live from the internal '15' rail which is fed from the fusebox and earth from the '31' rail which is fed from the brown wire out of the back of D/22 and finally the trigger for the relay comes from the rev counter feed from coil negative D/26.

    The main earth wire is worth a look, it should be plugged into a big white spade block near the fusebox which is on the end of the main earth from the battery. then there's a wire out the back of the spade block to the earth claw and you should also have an earth from the main dash harness and the fuel pump plugged into the front next to the fusebox earth. as a rule of thumb if a brown wire has a brown or black plastic spade housing on it then it plugs to the white spade block. if its plain or has a clear housing it goes to claw

    since the rev counter went nuts this might point to a poor earth somewhere or the hall sensor in the distributor has gone bad. the dash earth goes to a ring terminal on the side of the head, if the cluster works normally otherwise including mfa functions then this is ok. the spark module in the scuttle earths to the battery, check the pin connections on this for corrosion and pull the rubber boot off to check wire connections in the back and make sure the pins are fully inserted and tight. do the same for the hall sensor plug on distributor, and check over the wiring in general looking for electrical tape hiding previous bodges.

    fuse checks all sound perfect. 1-4 perm live, 11-19 ignition/x-relay live, rest are fused circuits only live when switched on (headlights etc)
     
  20. Freakum86 New Member

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    The rev counter didn’t go nuts just went up-to 10 the low rev for idle. so I need to find out why the number 5 fuse doesn’t come live at all. But the weather has turned shit now.

    In the wiring diagram you can see the j17 top is fuel pump relay. But their is 2 connections for the relay that are shown but no explanation

    so the issues I’m having is the 15line to the relay isn’t going live when cranking.

    what is the X-relay what’s it do
     
    Last edited: Apr 28, 2020

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