87 LT8, 4.1 Cadillac brougham ALDL scan

[kur4o]

A0022.ds PCM pn 1227056
Anyone successfully logged these PCMs.
I found that it needs some bpw grounding on Pin b.
Is there any other way to enter ALDL mode and force PCM to spit data.
I doubt there is a device that is readily available.

[billygraves]

Cadillac On-Board diags will give data via the HVAC by holding OFF and Warmer at the same time. You should have a crib sheet to understand and navigate the systems. Off-board the GM Tech-1 will access ECM data if I remember right. Tech-1 will keep all the systems running at a slow pace.
The data link is run by the Master of the link. (BCM, IPC, HVAC, ABS, ECM ect) The master sends out a request $F0 or is there anyone out there. Off-board must respond to the master with in a spec time and instruct the master to stop. If you do respond to the system and get the ECM, the systems go into default if you do not keep the others on the link satisfied with data needed to carry on. HVAC will go full defrost with heat, IP will not function ect ect. Best of luck