Manual Transmission T56 | T5 | MN12 | Clutches | Hydraulics | Shifters

A4 to M6 wiring question

Old 04-08-2012, 01:40 AM
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Default A4 to M6 wiring question

From what I can see from searching, you need to hook up the shifter switch's neutral wire to the clutch switch to be able to start the car and have the cruise control work. What if I didn't want to wire up that switch and still wanted the cruise to work, isn't the kill switch for the cruise the one up at the top and the "clutch down to start" switch the one at the bottom? Would I need to wire a toggle switch to the neutral wire to make the car think it's in neutral to start it the switch it off to make the cruise work? This is the only thing that is confusing me at this point
Old 04-08-2012, 09:30 AM
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the wire that kills the cruise is on the brake pedal. on a factory t56 car that wire is simply extended in series over the the clutch switch, that way if either switch opens it kills the circuit and the cruise. the neutral safety switch is needed to start the car. is there any reason you dont want to hook the neutral safety up to the clutch? i mean you could just wire it together but not really the best choice. i dont believe it would affect the cruise as i believe it just interupts the signal to the starter relay, though i could be wrong.
Old 04-08-2012, 10:12 AM
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Honestly I disconnect the clutch down to start switch on every standard I ever owned just cuz I like reaching inside the car to start it and I have enough sense to put the car in neutral every time it's not running. I know before I pulled the auto out, you could put the car in neutral with the cruise set and it will shut off. If the car thinks it's in neutral or park, won't it disable the cruise? Makes sense to me anyways. I think I got most of the other stuff figured out like not using a U bolt on the master cylinder. Bolts work just as well
Old 04-08-2012, 08:02 PM
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yea you are right about that, shift in neutral does kill the cruise... now im curious because i never hooked up the top anticipation switch on the clutch to kill the cruise (same as the brake one) and i know when i shift with the cruise enabled it has not killed it and i do have the neutral safety hooked up to the bottom clutch switch to start the car.

after researching schematics it seems as though those wires do not go to the pcm at all. instead i believe the pcm receives information from the auto trans as to what gear it is in, and then through pin 32 on the blue pcm connector kills the cruise. the ppl wht to drk grn (neutral safety) wires seem to be only isolated to the body, not pcm.

Last edited by got-a-ls1; 04-08-2012 at 11:45 PM.
Old 04-09-2012, 08:36 PM
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Originally Posted by got-a-ls1
yea you are right about that, shift in neutral does kill the cruise... now im curious because i never hooked up the top anticipation switch on the clutch to kill the cruise (same as the brake one) and i know when i shift with the cruise enabled it has not killed it and i do have the neutral safety hooked up to the bottom clutch switch to start the car.

after researching schematics it seems as though those wires do not go to the pcm at all. instead i believe the pcm receives information from the auto trans as to what gear it is in, and then through pin 32 on the blue pcm connector kills the cruise. the ppl wht to drk grn (neutral safety) wires seem to be only isolated to the body, not pcm.
So the cruise won't work anyways till I get the PCM reflashed? I lucked out here considering the PO of the tranny broke his leg and paid me with the T56 to put a TH350 in his car and he gave me all the plugs off the tranny harness. I can hook up the back up lights to the shifter sensor I suppose and lengthen the VSS hookup with the other piece of pigtail. I'm gonna forget about the reverse lockout and skip shift solenoid and have them tuned out of the computer completely. Hopefully that 7 year old write up on here about a swap out project covered all my bases
Old 04-10-2012, 06:00 PM
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I personally didnt hook up my cruise kill on my clutch pedal but I did hook up the neutral to the clutch switch. Dont use cruise at all anyways. got-a-ls1, what part of maine are you from.
Old 04-14-2012, 10:21 AM
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no your cruise will work without a reflash. i still have a automatic tune in my car. the computer reports the car as being in 2nd gear with the trans unplugged.
Old 04-16-2012, 05:45 PM
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Originally Posted by got-a-ls1
no your cruise will work without a reflash. i still have a automatic tune in my car. the computer reports the car as being in 2nd gear with the trans unplugged.
I heard they run like **** with an auto tune and that it won't idle at a stop
Old 05-20-2012, 09:36 PM
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Originally Posted by Boosterado
I heard they run like **** with an auto tune and that it won't idle at a stop
Mine runs great and idles like it did with the auto. Spins up really fast with the monster 18lb flywheel too. The most noticable thing is how far off the speedo is. When my speedo says 45 the car is at 105. Need a reflash to fix that but Im gonna wait till H/C/I and do it all at once. Otherwise it operates the same.
Old 05-20-2012, 09:38 PM
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Check this out in case of any more wiring questions or issues.
http://www.gmhightechperformance.com...p/viewall.html
Old 05-21-2012, 08:59 PM
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Sorry I didn't update. I just tuned the car and turned off all the auto BS. I also had the speedo set to a satellite speedo so everything is good. Everything worked after the swap with no problems
Old 05-21-2012, 09:19 PM
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Originally Posted by BlackLS1Bird
Check this out in case of any more wiring questions or issues.
http://www.gmhightechperformance.com...p/viewall.html
That woulda been damn nice to have about 2 weeks ago though
Old 05-25-2012, 05:10 PM
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Originally Posted by Boosterado
That woulda been damn nice to have about 2 weeks ago though
Yeah. Didn't see your thread in time. I posted it a few time in different threads in the manual transmission section before. Hope it is becoming useful. Might see if the mods want to post it as a sticky in that section. Seems to be a lot of A4 to M6 conversions out there.
Old 05-26-2012, 07:41 AM
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Originally Posted by BlackLS1Bird
Yeah. Didn't see your thread in time. I posted it a few time in different threads in the manual transmission section before. Hope it is becoming useful. Might see if the mods want to post it as a sticky in that section. Seems to be a lot of A4 to M6 conversions out there.
Hell I'm thinking about doing the mod for a few guys locally since my car went 2/10s faster as a manual and to make a few extra bucks. It's all to simple once you're done and looking back at it. Of course I think if the driver isn't a driving SOB, their car might go slower
Old 01-10-2020, 07:17 AM
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Bringing this thread back from the dead about the A4 to M6 and cruise issue. If the pcm is set to auto, and you have converted to manual, I'm getting a lag for rpm drop when stopped at a red light. It will usually hang around 1300 rpm for 2 to 3 seconds before coming down to idle. I have the brake and clutch switches connected in series. The cruise works fine as long as its set to auto. Buy... If I set it to manual, cruise is locked out. after looking at different diagrams, it looks like there needs to be a clutch start signal sent to pin C2 18 to keep the cruise from being locked out. Can someone enlighten me on this?
Old 09-06-2020, 12:38 PM
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Hi,
I've the same issue, I'm French, I had make the conversion A4 to MN6, and my Cruise don't working. My PCM is reflash to Manual.
I would like to restore my Cruise Control.

Do you have the Cruise Control wiring diagrams for MN6 and A4 ?


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