📍 Left frame rail below driver door, forward of rear axle
⚠️ Kelsey-Hayes 4WAL (4-Wheel Anti-Lock) rear-only system. Module and valve body integrated unit. Requires brake bleeding after replacement.
Engine Control Module (ECM)1.2 hr R&Rrelearn only +0.3 hr▸ programming details
📍 Behind right side of instrument panel, above passenger footwell
🔧 PROM chip replacement + idle relearn
⚠️ PROM chip must be transferred from old ECM or replaced with correct calibration. 1983-1985 use 160-baud ALDL; 1986+ use 8192-baud. TBI engines only; carbureted models have no ECM.
Transmission Control Module (TCM)1.0 hr R&Rrelearn only +0.2 hr▸ programming details
📍 Right side of engine compartment or under passenger seat (4L60-E equipped, 1991+)
🔧 Tech 1
⚠️ Only on 4L60-E automatic transmission models 1991-1993. Adaptive shift relearn via drive cycle.
Vehicle Anti-Theft System Module (VATS)0.8 hr R&Rrelearn only +0.2 hrwith PASS-Key theft deterrent (1991-1993)▸ programming details
📍 Behind instrument panel, left of steering column
🔧 10-minute relearn procedure
⚠️ Resistor pellet in ignition key. Module learns key resistance value. Replacement requires 10-minute relearn: turn key to ON, wait 10 min, OFF, repeat 3 times.
Radio (RAD)0.5 hr R&Rrelearn only +0.1 hr▸ programming details
📍 Center of instrument panel in radio cavity
🔧 Theft-deterrent code entry
⚠️ 1990+ radios with Theftlock require 3-digit code entry after battery disconnect or removal. Code on owner card or retrievable via dealer.
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 1985 Chevrolet S-10 2.5L I4 and can vary by trim.
🔧 Database maintained under the daily editorial review of Chris Hackleman · Master Technician · 20+ years and Jeff Moore · Master Mechanic · 20+ years.