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Old Mar 9, 2009 | 10:09 PM
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Default Big problems! Step inside

I just got done changing out my a4 wiring harness for an m6 harness, since i did the a4-m6 conversion about a year ago. Got everything buttoned up today and as soon as i connected the battery the starter engaged. After removing the starter and rearranging the wires, and it quit acting goofy. So with my spirits higher i finished up everything else went to go start it and i noticed that my fuel gauge is reading empty, completely empty, and my oil pressure is pegged. This is without starting the car. Then when i try and start it i have no fuel. The pump is not making noise and neither is the relay.

So im lost.

What i did notice is the two plugs that go thru the firewall on the passenger side had the pins in different locations than on the a4 harness. What do those pins connect when they are locked together?

My car is a 2002 and the m6 harness i bought was from a 2000 SS.

Any help would be greatly appreciated.
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Old Mar 10, 2009 | 01:14 AM
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I did the swap. I left the A4 harness.
All I did was run two new wires to the computer, one for the reverse lockout and one for the clutch pedal position switch. Way too easy.
It drives like it came from the factory with an M6.

I'm just saying that because I'm not sure what else you can do with this over the internet.
If I were you I'd put the A4 harness back in and do a rewrite entire with an M6 tune and you'd be driving it.

If not, get that A4 harness and ohm it out to find out where those wires go, I've done it before. I even have pic proof that I traced and soldered all 18 of them, these were on a different car with a cut harness.

I did have the pin locations of all those wires that plug in to the two harnesses that go into the pass firewall. All on that piece of cardboard to the right of the meter, it got lost though.

Last edited by 9000th01ss; Mar 18, 2009 at 12:17 AM.
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Old Mar 10, 2009 | 10:42 AM
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Ya it has been flashed to the m6 tune, i was under the impression that since it was on the m6 tune the pcm would be looking for those plugs which are in the different pins to the pcm. it makes me wonder why its not getting fuel. It must have something to do with the wires that pass thru the firewall. At least thats what i think at this point
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Old Mar 10, 2009 | 11:05 AM
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Do you have the A4 harness?
If you do, then all you have to do is ohm the ends and figure out where they went before and where they go now.
If you don't have the harness, I'd try to get one.

I have one thats not for sale for reference, but thats a long process going back and fourth on the internet.

I'm assuming you checked all the fuses, etc, the obvious stuff right?
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Old Mar 10, 2009 | 11:26 AM
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Oh ya checked fuses relays ect ect. I guess ill just hafta check out the plugs on the inside. Since they were different going from the a4 to m6 harness.
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Old Mar 10, 2009 | 11:53 AM
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I would highly recommend a factory service manual. The manual will have wiring schematics of both the A4 and M6 harness. You might even be able to find a PDF on the net or on this site.

I'm doing a similar swap in my GTO and the manual has been invaluable, and a huge time saver.
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Old Mar 10, 2009 | 01:42 PM
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I'm just having a hard time imagining what all is different. I have an A4 harness that ran fine with the M6 and M6 tune.

I'm leaning towards getting rid of that M6 harness you have.

Do you have the A4 harness? Will you please answer this?

It's pretty simple to ring out the wires from the two plugs to the ecm pins if you have it, if not I have the whole wiring schematics on CD I could , well I can't nevemind i cant upload it, i also have a wire harness, an a4 car, an m6 car but the communication lacks which adds to the difficulty of doing this online. Good luck.
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Old Mar 10, 2009 | 02:24 PM
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yeah i still have my a4 harness. Now that i think about it, the only things that are different between the two is the extra plugs for the T56 and the two plugs that go inside the car on the passenger side had a different arrangement in the pins on the blue and white plugs. I almost think thats where the problem is.
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Old Mar 10, 2009 | 04:46 PM
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It still makes no sense. I have a 2002 SS A4 converted to M6 and all I did was add two pins to the ecm. One for cruise control, one for the reverse lockout. And did a rewrite entire.

If I didn't want cruise or rev lockout I could have just done nothing with the A4 wiring.

If I were in your situation I'd look at every wire on the two ecm connectors, Every wire should match color and be in the same pin location.
the only difference should be fewer in the M6 and more in the A4.
There should be two extra wires in the plugs that go into the pass side. Those would be the same ones I added seperate on my conversion.
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Old Mar 10, 2009 | 05:08 PM
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ok ill take a look. Thanks man
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