⚠️ Analog clusters are non-electronic. Electronic clusters communicate via serial data but require no programming.
Transmission Control Module (TCM)1.5 hr R&Rrelearn only +0.2 hr4L60-E electronically controlled automatic (1991 only)▸ programming details
📍 passenger side of transmission tunnel, under carpet near transmission hump
🔧 Tech 1
⚠️ Only 1991 models with 4L60-E have TCM. Earlier TH400/700R4 transmissions are hydraulically controlled.
Electronic Control Module (ECM)1.2 hr R&Rrelearn only +0.3 hrfuel-injected engines only (TBI 1987+, TPI optional)▸ programming details
📍 passenger side firewall, behind glove box area
🔧 Tech 1 with MEMCAL/PROM chip swap
⚠️ Carbureted engines through 1986 have no ECM. Programming via physical PROM/MEMCAL replacement, not flash. Requires idle relearn after installation.
Aftermarket tool coverage varies by software version and vehicle build — treat "aftermarket tool" rows as "usually possible" and verify against your tool maker's coverage list before promising a customer. Spot a wrong location or hour? Tell us — corrections ship fast here.
Size-standard part numbers — verify your connector type before buying. Rear blades are model-specific; check the package's vehicle list.
Fuel economy figures are EPA data via fueleconomy.gov (median across matching trims). Performance figures are compiled estimates for the 1986 GMC Suburban 6.2L V8 and can vary by trim.
🔧 Built by master technician Chris Hackleman · Master Technician · 20+ years.