⚠️ 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.
THE RECLINER MECHANISM AND THE SEAT FRAME MAY HAVE FOAM AND/OR VINYL VETWEEN THEM, CREATING A "SOFT" JOINT. THIS "SOFT" JOINT RESULTS IN LOWER THAN SPECIFIED BOLT TORQUE WHICH LEADS TO JOINT LOOSENESS, CAUSING BOLT FATIGUE AND EVENTUAL BOLT FAILURE.
Consequence: IF BOLT FAILURE OCCURS TO THE DRIVER'S SEAT, IT WOULD ALLOW THE SEAT BACK TO SUDDENLY RECLINE, AND COULD RESULT IN LOSS OF VEHICLE CONTROL AND A VEHICLE CRASH WITHOUT PRIOR WARNING.
Remedy: DEALERS WILL REMOVE THE FOAM AND/OR VINYL FROM BETWEEN THE RECLINER MECHANISM AND THE SEAT FRAME "SOFT" JOINT AND REPLACE THE RECLINER BOLTS.
POWER TRAIN:AUTOMATIC TRANSMISSION · 93V016000
1993-02-01 · EA92009
UNANTICIPATED HEAT IN THE TRANSMISSION CAN FORCE THE TRANSMISSION FLUID OUT OF THE VENT TUBE.
Consequence: THE VENTED TRANSMISSION FLUID CAN CATCH FIRE IF EXPOSEDTO A SOURCE OF IGNITION.
Remedy: INSTALL A LONGER TRANSMISSION VENT HOSE ROUTED TO THE LEFT SIDE OF THE ENGINE COMPARTMENT OF THE VEHICLE.
Wiper blades
GMT400 platform (1988-1991 R/V-series). SUV with rear wiper.
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 1991 GMC Suburban 7.4L V8 and can vary by trim.
🔧 Database maintained under the daily editorial review of Chris Hackleman · Master Technician · 20+ years and Jeff Moore · Master Lexus & Toyota Mechanic · 20+ years.