Drivetrain Can I Use A9p Ecu With A T5 Manual Trans

Discussion in 'Fox 5.0 Mustang Tech' started by 07blowngt, Dec 7, 2013.

  1. Doing a t5 swap in a 93 notch. Did a 5.0 swap on this car and used a AOD. Now I am collecting parts to do a t5 swap and I thought I read a while back you can use a a9p ecu on a 5 speed. I can pick up a a9l local for $75.00.
    Would it make sense to just change out the a9p to the a9l, what all is needed to change both ways?
  2. What wiring harness did you use in the car? All AOD harnessed for the trans harness and o2 harness?

    If the entire car car was swapped using AOD harness, use the AOD computer is the short simple answer.
  3. Is the main harness the same? I thought there was a plug in harness off the main to the trans? The entire harness is off a 93 which was diff from the older because of a relay for fuel pump. If I use the existing harness on the t5 with the ecu I wont have to change anything at all
  4. once you start swapping harnesses from different years and/or auto/stick, you are going to run into all kinds of issues with sensor/relay connection compatibility. I don't have it off the top of my head but there are differences in harnesses

    pre 87 are not MAF
    88-89 has MAF no airbag
    90 maf and aribag fuel relay under seat
    91-93 maf and airbag fuel relay not under seat

    The o2 sensor connections are different from stick to auto as they have different number of wires.

    You can use an A9P in a stick but not an A9L in an AOD.
  5. So it sounds like I will be OK all my harnesses are from 1993. My main harness is late 92/93
  6. From an AOD car, or a 5spd
  7. An A9P will work OK in a 5 speed car with a 5 speed O2 harness. I have done it and it worked OK.

    What I haven't done is to use an A9P with an Auto trans O2 harness in a 5 speed car. I can't say if that will work or not. I have my suspicions that there will be some no crank problems with the starter circuit.
  8. So I guess I will change out my o2 harness. what is the diff between the 2 ?

  9. Take a look at a diagram and you will see one grounds internally and one uses an external ground wire, Use the wrong harness and you can fry the computer.
  10. Go unplug your 02 harness, and start the car. Your suspicions will be gone. The 02 harness doesn't interupt the starter circuit.
  11. You dont need to source another 02 harness. You simply re-pin the harness you have now.

    Since you will be running a 5 speed transmission. Your loop on the back of the 02 harness needs to connect a blue/yellow wire to a purple/yellow wire. Look at how the harness is setup now. If its a mass air 02 harness, it will have a looped wire on the back of it. The loop is either purple/yellow or blue/yellow. And in factory AOD form, it should be connecting a white/pink(or purple), to a purple/yellow wire. Which is what you dont want when its converted to a 5 speed.