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Running cables through firewall - 1998 A4

Discussion in 'A4/S4 forum(B5 Chassis)' started by brettfk, Jun 15, 2010.

  1. brettfk
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    brettfk New Member

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    [Jun 15, 2010]
    Hi all,

    I am the proud owner of a 1998 A4 sedan. I am currently wiring up a 240V power inverter in the car which I want to have running directly from the battery.

    So far so good, I have got the cabling to the front of the car, and rigged up a ring terminal and in-line fuse which is now connected to the battery.

    However, I am stuck with the next step. I want to get the cable through the fire wall, but I don't know where the gap is to do it. I know in my '96 sports it was behind the glove box; think it will be the same here?

    I haven't looked 'coz I really cant be bothered pulling it all out and etc.

    Cheers fellas.:eyebrows:
    #1
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  3. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Jun 15, 2010]
    Easiest route is via the ECU cover, this drops down into the drivers footwell, theres even a spare grommet on the ECU cover.
    #2
  4. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Jun 15, 2010]
    as above. If you look at the big rubber grommet that the main wiring harness enters the ECU box thru, you'll see a little nipple at the top. Snip the end off the nipple and you can feed the wire thru.

    Alternatively if that nipple is in use (its used for cruise control afaik) you can punch a hole thru the rubber grommet quite easily. Look on the inside and you'll see two triangular spaces that you can punch thru.
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  5. phoenixv6quattro
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    phoenixv6quattro staylowmovefast

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    [Jun 15, 2010]
    #4
  6. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Jun 15, 2010]
    I dont see how its much better?

    You have better access to the ECU box than the grommet thats under the pollen filter (i had originally thaught you'd routed it thru the pollen filter housing, but reading it again it seems you've used a grommet underneath it?)

    Removing the glovebox is about the same work as removing the drivers knee bolster (drivers bolster is probably easier if you wanted to split hairs, as theres less bolts and less wiring plugs)

    An alternate route maybe, but i cant see why its better or any more convenient?

    Depending on the current draw, you might not even need to pull it thru the firewall anyway, as the central electrics panel has a heavy guage wire directly from the battery bolted to it already.
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  7. brettfk
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    brettfk New Member

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    [Jun 16, 2010]
    Thanks heaps for the info guys.

    I'm probably going to go with running it under the pollen filter for now as I have run the cable down the passenger side of the car anyway, not sure that I have enough slack to get it to the drivers side.

    Just so I know, how exactly do I a. find and open the ECU box, and b. find the central electrics panel (I assume you're not talking about the fuse/relay panel?)

    Cheers guys.
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  8. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Jun 16, 2010]
    The ECU is inside the box on the drivers side just under the wiper scuttle. Remove the 8mm bolts, there is one right at the back that you'll struggle to get to, but you can prise up the top cover without removing it which should give you enough space to run the cable.
    The central electrics panel is under the drivers knee bolster behind the fusebox.
    #7
  9. phoenixv6quattro
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    phoenixv6quattro staylowmovefast

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    [Jun 18, 2010]
    Aragorn, you don't actually have to remove the glovebox. You can do it just by removing the cover for the pollen filter, popping the grommet and poking the cable through. Then a bit of feeling around in the interior will reveal the cable. The glovebox in mine is off in the pic because I replaced the blow unit (again! You buy cheap you buy twice!!!-learnt my lesson now!!!). I have since removed the + cable and replaced it with a more conductive one, as the last one was an ebay special! I replaced it using the method stated above. That aside, if you havn't got a lot of cable to play with, you will lose more of it going via the ECU, as opposed to the grommet under the PF.
    #8

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