Fusebox FAQ

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

  1. rubjonny

    rubjonny Administrator Admin

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    if the fuel pump ran fine with the x relay 17 or 18 swapped into slot 2, you have ruled out all the internal connections for live, ignition live, earth and output to fuse 5. that leaves you with either a dead fuel relay, or an issue with the rev counter signal back to the fusebox. since the rev counter appears to work then just leaves you with faulty relay. but dont worry about the relay for now, concentrate on getting the car running just leave the x relay in that slot for now.

    the output from fuse 5 goes to E/14 which is fed by fuse 5, powers the fuel pump and also a male spade which then powers thye AAV and WUR in the engine bay. Also feeds big spade N before the fuse, but this is unused on the kjet 8v so no need to worry about that. N is used for some versions of digifant injection, on carb engines it feeds the inlet manifold heater and on diesel engines its for glow plugs

    unless you mean the extra connections for the relay socket, unless they are shown connected to the relay they are unused. pins 6, 7 and 8 on the socket are for other engines and not relevant to the kjet injection.
     
  2. Freakum86 New Member

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    The only way the pump for me has run so far is with a direct 12v feed from the battery. I’m struggling with all this as I’m 6”7 and the cabriolet is very low. The fuse box is under the dash and there are a lot of sharp edges in the car.
    When I swapped relays nothing happened. Pump won’t run. But pump works when tested so supply issues this is why I was at the fuse box. So fuse 5 is switched on by the relay and directly supplies the pump.
    the issue then is to get the relay to turn on which it isn’t. As I’m not getting 12v to pump when cranking or ignition on.

    The N spade yeah saw that and tested continuity but listed as glow plugs so makes sense it’s unused.
     
  3. rubjonny

    rubjonny Administrator Admin

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    ok, if the pump doesnt work with the 17/18 relay in slot 2 look at the main earth to the fusebox I mentioned from the back of plug D, if thats gone the car will do odd things. the live to the relay socket comes from the P spades on the back, this feeds all the permanent live feeds though so this isnt the issue as you checked the lives at the fuses 1 to 4. the ignition live comes from the ignition switch, again you checked all the fuses which should have ignition live and they do also.

    another thing you can try, if you loop a live into spade N this will back feed fuse #5 and tell you if theres an issue with the fuse socket or not. another thing you can do is make up a looped bity of wire and put it between the 2 large terminals on the relay socket, this will tell you if theres an issue on the main input and output pins on the fuse socket
     
  4. Bomber604

    Bomber604 Forum Member

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  5. rubjonny

    rubjonny Administrator Admin

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    you're welcome :)

    interesting reply format though, inside a table inside a quote :lol:
     
  6. jimmy2gti New Member

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    Apologies if this has been mentioned in a different topic,
    im trying to find wiring info/diagrams for the early MK2's using MK1 MFA (pic), in my case a january '84 mk2 gti. So far ive been trying to work it out combining mk1 and mk2 wiring info. I also have problems like, instead of the upshift light kicking in at the appropriate rpm, i get a constant light at flasher indicator led, that causes the flasher relay to buzz. The economy gauge isnt working as well. Any info or advice on how to troubleshoot this would be great.
    Jim

    20200515_232313.jpg
     
  7. rubjonny

    rubjonny Administrator Admin

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    hello there, if you look at the CE1 section towards the bottom there is a full pinout for the CE1 MK2 cluster, plus the wiring you're looking for for vacuum switch and 5th gear switch for the mpg gauge are wired to plug D then from there into the dash loom. you should have a control relay in slot 4 for it also.

    I would start by checking the cluster earth to the side of the head, its the brown/white wire it runs to a spade plug on the bottom of the clock plug :)
     
  8. jimmy2gti New Member

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    Do you mean the brown wire that goes to the long side of the white plug? Or is it an extra earth for MFA models im missing
     
  9. rubjonny

    rubjonny Administrator Admin

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    yes on the cluster its brown, it leads to a male spade with a wire from the mfa stalk, then theres a brown/white wire from that in the engine loom off to the side of the head :)
     

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