As information is discovered about various GM ECMs, it is maintained in this archive. Please send corrections and additional info to the GMECM list for discussion

C3 information
Generic P4 information
OBD2 PCM info ECM info by ECM part number

ECM part number ECM family Application/Description
1227747 C3 '87-'91 GM trucks (aka Programming 101)
1228746 C3 '89-'92 Car V8 TBI applications (F body, Caprice)
16159278 P4 '92-'93 LT1 (F body/Vette)
1227730/1227727 P4 '90-91 F/Y body, lots of others. 1227727 is an underhood (weatherproof) version of 1227730
1228331 P4 '90-91 Y body ZR1, LT5 engine
1227748 P4 '87-'88 2.5L4 Fiero, others
1227749 P4 Syclone, Typhoon, others
1227165 P4 '86-'89 V8 TPI, some L4 TBI
1227808 P4 Australian version of 1227165
16196396 C3 '94-'95 GM trucks 5.0L, 5.7L TBI manual transmission
16197427 P4 '95 GM trucks 4.3L, 5.0L, 5.7L 4L60E
16171199 P4 '95 GM trucks 4.3L, 5.7L, 7.4L 4L80E
16250279 P5? (68332 based ECM) '98 GM trucks
northstar Cadillac