Automatic to manual swap

Tiny
BRUCEM MATAVA
  • MEMBER
  • 2005 MAZDA 3
  • 1.5L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 150,000 MILES
Changed an automatic into a manual, no spark.
Thursday, April 25th, 2019 AT 2:48 AM

5 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Hi Brucem,

I would put my money on the fact that you are going from the auto transmission using a park/neutral safety switch to a clutch pedal position switch.

If you did not do anything with the PCM then it is still looking for a the P/N switch on the side of the transmission. It is not seeing that so it will not allow it to fire which it will do by not delivering the spark.

I included the info for both the P/N switch and the clutch pedal position switch. My guess is the way to do that is you need to put a PCM in the vehicle that is set up for a manual trans. Or at least tell the PCM that it is now a manual transmission. There may be some programming tools out there that do that, but I am only aware of replacing the PCM with one set up for a manual.

If you already addressed this, then let me know and we can go further.
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Friday, April 26th, 2019 AT 11:40 AM
Tiny
BRUCEM MATAVA
  • MEMBER
  • 3 POSTS
That I have done, but the other thing is the old engine and ECU are from a 1.5 liter and now the new body had a 2 liter engine.
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Monday, April 29th, 2019 AT 3:23 AM
Tiny
KASEKENNY
  • MECHANIC
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Okay. So what exactly have your changed? Sounds like you changed a lot more then just an auto to a manual. You changed the engine as well? Was there anything else? If you have a completely different engine but still have the ECU from the old engine, then this will need to be addressed.

Just let me know everything you have done up to this point so I can review that and let you know what it could be. Without all the info, my advice will seem pretty useless.

Thanks
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Monday, April 29th, 2019 AT 10:54 AM
Tiny
BRUCEM MATAVA
  • MEMBER
  • 3 POSTS
The thing is I had a 2005 mazda 3 1.5ltr manual transmission that was involved in an accident after that I bought a body and this body had a 2ltr automatic transmission. After moving all the mechanical parts including the ecu the engine could not crank, the other thing is the ecu harnesses were different from the 2 cars. Could there be differents in circuiting
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Monday, April 29th, 2019 AT 11:08 PM
Tiny
KASEKENNY
  • MECHANIC
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Just so I am clear, you used the wiring from the 2.0L and auto transmission? Did everything plug in or do you have some connectors that are not plugged in? I don't see how the ECU out of a manual and different engine can communicate on a harness that does not have the same circuits. I would suggest swapping the engine and transmission harnesses over from the old car and then retesting.
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Tuesday, April 30th, 2019 AT 5:00 PM

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