I'm just starting to get into prom burning so bare with me plz.

When I bought my parts car (87 GTA) it had one ECM running the car and the guy threw in another ECM.
When I opened the ECMs and compared the memcals I noticed the ECM that was running the car was missing a piece from the memcal.

On the extra ECM there are 3 chips (the eprom and 2 others that look the same). Above the 2 similiar chips there's a small pcb.

The ECM that was running the car didn't have the little pcb. What is that thing? What is it for? Part of the "limp home" circuitry?

 

Sounds like the knock board (electronic filtering system for the knock sensor (KS)).

The two other chips that "look the same" as the EPROM (but don't have the erase window) are the "network resistors" (netres). These have the electronics for the "limp home mode".

John

 

If the car is wired for the original ECM, which it probably is, then the PROM that is needed to run the factory ECM will not have the extra KS circuitry on it. It's because you have an Electronic Spark Control module (ESC) somewhere in the engine compartment. So the fact that your MEMCAL running the car is missing a piece really doesn't hold true...it just doesn't have it cause its not supposed to.

In 90, they made a change to a different ECM. They no longer had the ESC module, cause the stuff took place on what John was talking about.

 

Here's a pic of what my "extra" ecm memcal looked like.

https://www.thirdgen.org/newdesign/t...om/1138119.jpg

Let me see if I got this right; pre 90 cars had either a pcb on the memcal or a seperate ESC module under the hood. 90 and up had neither the extra PCB or the underhood ESC module?

 

ANJx,looks to be a 90 memcal for a 730 ecm'd car.
If you can read all four letters and post that, maybe someone will look it up and let you know what application it's for.

The 87 MY ecm should be a 1227165, and that ecm's memcal doesn't use the added PCB.

 

The one in the pic is for a '730 TPI equipped SD car with a 5.7l auto.

Desirable MEMCAL, just won't work in a '165 EC<.

RBob.

 

I too agree that it looks like a 7730 Memcal. Possibly the previous owner planned on swapping to a 7730 or he bought an ECM on e-bay and bought the wrong one, not realizing the differences between the two.

Does the spare ECM have a spot for 3 connectors or 2?

 

Notice the main body is Lt. brown mostly likely a V-6 prom. ours are usually black. ( for V-8 )

 

That is not always the case. My original AUJP Memcal that came in my car has a brown main body, while my second AUJP Memcal that I purchased a couple of years ago has a black main body.

I also have an original V6 Memcal at it does have a brown main body. Maybe the "black" vs "brown" means original vs. subsequent release.

 

ANJF

Model Year: 1990
Release date: 5/19/89
EPROM Part Number: 16134306
ECM Part Number: 01227730
PROM ID: 4307
SCAN ID: 5181
Platform: Camaro/Firebird
Engine RPO Codes: L98
Engine Displacement: (L) 5.7
Transmission RPO Codes: MD8 (Auto)

Replaced by the AUJP that is very common for these cars.

The MEMCAL is for a 1990 speed density system and would not work correctly for an earlier MAF system.

The per-90 cars, with a MAF sensor, didn't have the circuit board on the MEMCAL. There would be a ESC module somewhere around the MAF and fuel pump relays.

The 90,91,92 730 speed density cars have the circuit board (that's the electronic spark controller) on the MEMCAL as the one in your picture does. It does NOT have a separate ECM module mounted under the hood with the relays mentioned above.

In either case, there are two small chip and one large chip on the MEMCAL. The larger one is the PROM chip, (where the program is stored) and the other two small ones are the limp home chips, cylinder select hard wiring, and I don't know what else.


Hope this helps.

 

Thx for the replies.
The pic I referenced was only an example I found on the prom intro page. I was just trying to make a reference to the little pcb.
Sorry abt the confusion..
My "extra" memcal (with the ESC pcb) has the following notation on the EPROM window sticker: ADRA

A friend (IT guru) borrowed my pcb-less memcal (and my extra ECM) to build a simulator. Guess I better get it back before he gets too carried away.