BCM and ECM question

[Guest BREH]

Are The BCM and ECM's The same for THE 88 89 90 & 91's ???

THANKS.

[Guest CL_Reatta]

I know that the 91 ECM is different because of the Tuned Port Injection, I am not sure about the other years/computers though

[padgett]

Oddly enough I show the same ECM part numbers for all four years. The PROM is different for each year and the 91 has the E-trans but apparently the same computer.

[manikmekanik]

Yes, the ECM mainboard is identical for all 4 years, the prom will change for later model, due to trans and engine upgrades.

When you replace such a unit, you MUST insert the PROM (Programmable Read-Only Memory) chip which was originally in your car.

[Jim]

From my experience and from my GM factory parts and illustration catalog both the ECM and BCM are different in the '91s from the '88-90s.

ECM------

The book shows 1228253 for all years '88-90 but also many '89s came with a 16198264. These two ECMs will interchange but as mentioned you should use your original PROM. The ECM for a '91 is 16141470 and the colors on the connectors are also different.

BCM------

The book shows 1227253 for 1988 and 1228786 for '89-90 but in dismantling many '90s I have found quite a few to have the 1227253s in them from the factory. Again both numbers should work but in this case you definitely have to put in your original PROM.

The p/n for a '91 BCM is 16137944 and like the ECM it has different color connectors.

[padgett]

Thank you Jim - I had wondered whether the -253 had all of the drivers necessary for the E transmission.

BTW the BCM has two PROMs not one, a 27C256 and a 28C16 and both are in black carriers that do not look anything like (are much smaller) than the blue CalPak in the ECM.