1991 Riviera ECM question

[Aztec]

Hello,
my name is Henning, I am living in Bremen, Germany.
I have a 1991 Buick Riviera.
Motor GM 3800 L27 VIN L.
I have the Buick Service Manual.

With the help of the on-board diagnosis I have discovered that the ECM (or PCM) is not sending any data.
I am unable to read any data from the ECM/PCM.
The BCM is sending trouble code b334c "Loss of ECM data"

The ECM/PCM I have has the part number 16141470 and the code "AXMU".
I think "AXMU" is a designation for the "MEM-CAL" chip used in the ECM/PCM.
I wonder if this is the correct unit for the car, since the words "on loan" (in German Language) have been written on it.
This tells my that this might be a ECM/PCM from another car.

The BCM is a 16137944 code "AWAC" unit which I believe is the original unit, installed in the Buick factory.

Can anybody please confirm that "AXMU" is the correct ECM/PCM for a 1991 Buick Riviera?

Will any 16141470 unit work in my Riviera, no matter what code?
What is the meaning of the four letter code (like "AWAC") anyway?

Henning
Bremen, Germany

 

[MelsRegal]

according to www.rockauto.com part number 16141470 is correct for your car

http://www.rockauto.com/en/catalog/...cal,engine+control+module+(ecm+computer),2896

 

[HotZ28]

Can anybody please confirm that "AXMU" is the correct ECM/PCM for a 1991 Buick Riviera?

AXMU is the MemCal ID. http://www.oreillyauto.com/site/c/d...76500_-1&pt=C0277&ppt=C0150#compatibilityTab_

Will any 16141470 unit work in my Riviera, no matter what code?

Yes, that is the correct part number for the ECM/PCM or (Cardone Part Number: 77-1470) but the MEMCAL will have to be removed from the existing unit and installed in the new/rebuilt unit. http://www.cardone.com/Products/Product-Detail?productId=771470&p=rock&jsn=785

What is the meaning of the four letter code (like "AWAC") anyway?

That is the MEMCAL ID and the following numbers/letters would be the broadcast code.
http://r.search.yahoo.com/_ylt=A0LE...0001.pdf/RK=0/RS=iUdhrcP34QjOq8.OgC.HXxiHfUE-

 

[Aztec]

OK, guys,

thanks for your help. I can confirm "AXMU" is the correct "broadcast code" for my Riv.
I have found that information here: http://workshop-manuals.com/buick/r...able_read_only_memory/99-06-04-053/page_3405/

I understand that I can use any 16141470 ECM unit, as long as I use my AXMU MEM-CAL chip.
What happens when I try a used 16141470 ECM with a MEM-CAL chip from a different car, say a Park Avenue or a Pontiac Trans Sport?
These cars use the 16141470 ECM, too. Only the MEM-CAL chip is different.

 

[HotZ28]

I understand that I can use any 16141470 ECM unit, as long as I use my AXMU MEM-CAL chip.
What happens when I try a used 16141470 ECM with a MEM-CAL chip from a different car, say a Park Avenue or a Pontiac Trans Sport?

That would only work if the MEM-CAL has the same ID & broadcast number. As you can see, the 16141470 ECM was used in a lot of different vecicles with different engines & drive-trains, so the chips are what contain all the parameters for any particular vehicle. BTW, do you have any problems with the engine running, or related drive-train problems, or is just the fact that the ECM & BCM fail to communicate? If the latter is the case, that is explained in the Technical Service Bulletin link you provided.

 

[Aztec]

Hi Hot228,
remember me? I was pretty busy in the PA forum with my 91 Park Avenue a year or so ago.
Now I have a 91 Riv.
My problem is that the BCM & ECM fail to comunicate and the fact that the the onboard diagnosis tells me that the ECM does not comunicate at all (NO ECM data). With ignition on, the temp gage shows the temp is going up and down very quickly, the SES light flickers and one of the fans starts and stops spinning, all with the same tempo.
I am pretty certain the ECM is toast.
I got me a used 16141470 ECM unit from a Pontiac Trans Sport 3.8 which I want to try.
I will swap the mem-cals of course, but out of curiosity I wanted to know what happens if I don`t do it.

 

[HotZ28]

The Mem-Cal is programmed specifically for the vehicle engine, gear ratio, speed sensor and many other other parameters. If you do not have matching parameters, engine performance & trans functions would suffer. If the Trans Sport has the exact drive train, gear ratio & speed sensor, (which I doubt) it may have the same prom ID & broadcast number?? According to the TSB you posted, there was a new version of the Mem-Cal produced that will allow communication between the BCM/ECM. So, I assume if you replace the ECM and use the existing prom, you will have the same problem.

 

[Aztec]

I will get the ECM today and try.
I will let you know.

Henning
Bremen, Germany

 

[Aztec]

100% success!
I have installed the riv`s mem-cal chip into the new ECM, plugged it in and voila! No temp gage going wild anymore, no trouble codes and all modules are sending data.
I´m lovin`it!

Henning
Bremen, Germany

 

[txbarney]

Great to hear a success story

 

[HotZ28]

100% success!
I have installed the riv`s mem-cal chip into the new ECM, plugged it in and voila! No temp gage going wild anymore, no trouble codes and all modules are sending data.
I´m lovin`it!

Henning
Bremen, Germany

Thanks for the update, you are a wizard! I do remember you from the PA forums, and hope I was able to offer some advice to help resolve some of the problems on both of these vehicles.

 

[Aztec]

Hot228.
wait for it, the motor of my Riv isn`t running yet!
The car has been standing unused for a very long time and the gas in the tank went bad.
The fuel pump is blocked.
I am now waiting for a new pump and when I have it the gas tank will have to be reinstalled.
Only then I will now how good the motor really is.
All brakes were seized, a heap of rust, tires are 15 years old.
But the body has no rust, paint is nice (antelope) and the leather interior is good.
The car has 111000 miles on the clock.

It is a much better project than my PA ever was.
Over here, a 91 Riviera is an extremely rare sight.

Henning
Bremen, Germany