Differences in PT3 ECU's? - Diagnostic LED Yes or No

[ACCLUDE91]

I've got 2 PT3's sittin side by side and one has a LED in the D11 spot and a little clear window on the top cover so it's vissible. Kinda resembles a OBD0 lol

Here's the specs

With LED:

37820-PT3-A21
324-104955
1L09
AZM
manual trans
mfg date - 12-08-89
Board looks identical to the 1190 board but does not specify,
only says - N6Y-J W6101-PT3-003
came from a 91 EX coupe

Without LED:

37820-PT3-A23
324-521435
1D30
AZM
manual trans
mfg date - 05-08-?? (year is not stamped)
Board is a N6Y-K 02D01190-1504
also came from a 91 EX coupe

Wondering if anyone knew the differences and if not, just take the poll and state what year/model car to help figure out what the difference is.

Both cars had functioning CEL check connectors and working CEL light in the cluster so there was no need for one on the ECU. It reminded me of a OBD0. MY guess is that the A21 model w/LED was borrowed from another car (possibly OBD0) and adapted to the CB and the A23 w/o LED was when it started to be made specifically for the CB. Just curious if anyone can shed some light.

[ACCLUDE91]

I know some of you guys have PT3's laying around that you could look at.....and it's not hard to pull up the capet a check for the LED (should be visible without even taking out the ECU preotector plate). Help me figure out why they are different.

[cp[mike]]

never seen one with an LED, though IIRC every ECU mount plate has the hole in it to see the LED.

[oneoffaccord]

im with [cp]mike never seen one with a led. the only accord that ive seen it in is the 3rd gen.

[bjaccord]

1990 EX 2dr coupe Automatic (F22a4)
Vin is 1HG, made in the U.S. if that matters

Mine had one, I remember this subject came up like 6 years ago on Superhonda.com and I ran out to my car to check, lol.

I no longer have it as I sold it years ago as an ex ecu (Whoops, kid probably wanted it for iab's, but what the hell did I know then?)

Any way, good luck in the research, anything in particular your trying to learn or just curious?

L8r

[aero]

Never seen one. I have had 2 1991 accord lx's, one 2 door, other 4 door, and neither had a window or LED.

[ACCLUDE91]

I really think it's gonna be a mostly 90 Accord thing that might have carried over to the 91's but some of 91 and all of 92 and up got rid of the LED's entirely.

This is really no big deal, I'm just curious to find out what the difference is besides the obvious LED.

Here's some pics:

W/ LED


Notice the clear window and notice the big circular red thing in the top corner

W/O LED


No clear window and no bright red LED in the corner either. *edit* - pay no attention to the fact that it's de-ROM'd -

[cp[mike]]

im going to put a resistor and LED into an ecu and see if it works, what are the colors on that resistor?

[RENR]

w3rd.i seen one on a 90 automatic.

[gdout90accord]

i think automatics has them leds but not sure.....

thats just to check your CEL codes

[accordaffair]

The one I removed from my 90 lx had one, but the pt6's I replaced it with do not.

[ACCLUDE91]

cp[mike]- I'lllook at it when I get a chance, it's up at work now. I don't think it has any resistors....just a 5V LED but I will double check. It's in the D11 spot.

gdout90accord - we all know what it's for And the ECU's I have are all manual. It has more to do with the year than the tranny type.



So I think it's what I originally thought....it was borrowed from another car (probably OBD0) and adapted to the CB's in the 90's so all (or at least most) 90 Accords have the LED PT3's. It carried over to some of the 91's but some have the LED while most do not. Then for 92-93's NONE of them have the LED. As for the PT6's, there were none in the 90 models so they shouldn't have a LED (except MAYBE some of the 91 models). If you guys have proof that this is incorrect, please post it.

[blackice]

My first cb7 (1990 Accord EX coupe with auto f22a4, also 1HG vin) didn't have the window and led. I'm curious if specific ranges of vin codes had those ecu's...

[DjSpeedy]

1990 accord lx automatic. I had the l.e.d but I put in the pt6 and now I dont. Oh well.

[Shippo]

90 manual DX has it