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I spent way too much time analyzing the ECU part numbers at car-parts.com. Here's what I found. Legend ECU's are numbered thus:

37820-PY3-A55

The first 5 digits are almost always the same.
The next 3 digits seem to designate Type 1/2.
PY3 == Type 1
PX9 == Type 2
The next digit seems to indicate emissions.
A == FED
L == Calif.
C == Canada?
The final two digits appear to be software revision numbers, larger is newer I assume.

Here are some oddballs that I found:
39900-SP1-A1
37820-PG3-xxx
-PX3-xxx
-PL2-xxx

For 1991-1992, the FED Coupes and Sedans seem to use the same part numbers 37820-PX3. The auto trans cars use -A52, -A53, and -A55. The manual trans cars use -A02, -A04.

For 1993-1995, it gets more complex. The auto trans units seem to use the 37820-PX9. An exception seems to be the L Sedan Auto which uses the PY3-A57, -A58, or -A72.

The 1993-1995 GS manual trans uses a PY3-A09. The manual trans coupe LS uses a PX9-A17

I haven't catalogued the California numbers. But the trend seems to be the same: low software numbers are for manual trans, and higher numbers for auto trans.

I think it would be a fun project to create and publish a software library of all these original Acura ECU programs. I DO NOT advocate cloning aftermarket ECU programs such as Bayou.

Think how much easier it would be to swap engines or transmissions if you could simply reprogram your ECU for the proper combination? I wonder what differences in power or drivability there are between the different revisions?

If anyone wants to help with the project, PM.

Cheers, Cap
 

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*r**h *eller
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Very usefull information. I'll sticky it here for a while. Probably eventually move it to Usefull Topics forum.
 

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GS Hog
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Good job, Cap!

Just one note though. My '94 GS 6-speed uses ECU # 37820-PX9-L17 (CA car), and the Fed counterpart is, as noted, 37820-PX9-A17.

The ECU # 37820-PY3-A09 I'm guessing may be for the '93 - '95 L Coupes.
 

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This is a good thread. Glad I searched for it.
I'll add to the list-

I have a 1995 Legend L Coupe (Automatic), California car all its' life so I assume it's a California-ECU edition.

ECU CODE: 37820-PX9-L57


Some of the ECU variations might be due to TCS, mine does not have that function. (L Coupe)
 

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you guys got some balls to remove that. i'm not touching that thing! hahahha
 

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OK so here's the part number from the six speed I have 37820-px9-a05, I can't find the A05 anywhere.
I guess the car you're referring to is the one listed in your vehicles to the left right under your name.
If that's the case it wouldn't give any meaning listing your ECU code since your car has been modded. No 92 Legend has a 6-spd transmission. It doesn't make sense if you're trying to make the numbers provided here seem wrong.
 

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I also have an a15 from a t2 6mt, both are stock stickers I think there is another explanation besides being modded. It could be different years or places of manufacture, software ...??? Hmmm
 
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igght need help

my ecu iz dien on me does any one kno any good sites with good price on them? an duz the serial effect mE replacen the part?..im noob wen it come to dis type of stuff
if it help_my car iz 93' legened coup type2 serial# 37820-px9-a54
 

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my ecu iz dien on me does any one kno any good sites with good price on them? an duz the serial effect mE replacen the part?..im noob wen it come to dis type of stuff
if it help_my car iz 93' legened coup type2 serial# 37820-px9-a54
Is your car automatic Type II with TCS if so I have the ECU you need. I should be recieving my new chipped ECU from Telion Friday and I will sell you the one in my 1993 coupe. I am also in Florida. Hit me via PM if you are interested.
 

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Ok, I am bringing this topic back from the hidden depths, and looking for opinions or advice. I have a 1989 Legend 2 door manual transmission. It has a bad surge problem and came up with a code 4 for the crank sensor. I changed the sensor, but the surging is still here, and the code went away. I did a little research into what can cause the surging, and tracked it down to the idle control valve not functioning properly. Testing the valve and wiring harness according to my Haynes manual, I have power to the valve when the ignition is on and motor not running. The manual recommends taking the car to a service shop as the ECU maybe faulty. I did a little more studying to tell how to know if the ECU is bad, and came up with if the check engine light does not come on upon turning the key in the ignition, that is a code 0, and a faulty ECU. I have 1988 Legend 2 door automatic transmission parts car. The check engine light does come on upon turning the key. I am going to swap the ECU out of the 88 into the 89. I read you can put an automatic ECU into a manual, but can't put a manual ECU into an automatic. Anyone see any problems with this? The manual transmission ECU part number is 37820-PL2-A43, and the automatic is 37829-PL2-698. The only thing I can see would be a problem is I think (think the key word here) is the automatic ECU is California emission and the manual is Federal emission.
 

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Update: Swapping out the ECU did not help with the surging. I put the original ECU Back in. The check engine light must have burnt out around the time I was researching how to tell if the ECU is bad, as I know I had to reset the ECU a few times to get the light to go out. Back to the old drawing board I guess. Lol
 

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Gen A ECU'S (1991-1992)

37820-PY3-A52: USDM Type I, Automatic
37820-PY3-A53: USDM Type I, Automatic
37820-PY3-A54: USDM Type I, Automatic
37820-PY3-A55: USDM Type I, Automatic
37820-PY3-A02: USDM Type I, Manual
37820-Py3-A03: USDM Type I, Manual
37820-PY3-C52: Canadian, Type I Automatic
37820-PY3-L52: CALI, Type I, Automatic
37820-PY3-G52: EDM, Type I, Automatic
37820-PY3-J03: JDM, Type I, Automatic (note center digit doesn't follow A/T pattern above)
37820-PY3-Y52: Gulf Spec, Type I, Automatic

Gen B ECU's (1993)

37820-PY3-A06: USDM, Type I, Manual
37820-PY3-A57: USDM, Type I, Automatic
37820-PY3-A58: USDM, Type I, Automatic
37820-PX9-A04: USDM, Type II, Manual, NON-TCS
37820-PX9-A15: USDM, Type II, Manual, TCS
37820-PX9-A55: USDM, Type II, Automatic, NON-TCS

Gen C ECU's (1994-1995)

37820-PY3-A72: USDM, Type I, Automatic
37820-PX9-A57: USDM, Type II, Automatic, NON-TCS
37820-PX9-A67: USDM, Type II, Automatic, TCS
37820-PX9-A68: USDM, Type II, Automatic, TCS
37820-PX9-L67: CALI, Type II, Automatic, TCS
37820-PX9-A17: USDM, Type II, Manual, TCS
 
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