Bought a used ECM, PCM, or BCM?
We make it start.
A used engine computer from a junkyard, salvage yard, or eBay will not simply plug in and run — it still carries the donor car's software, VIN, and anti-theft pairing. Spot-On programs and clones used ECM, PCM, and BCM modules for vehicle owners at our San Antonio shop, by appointment: we confirm the part matches, transfer or rewrite the software, and marry the module to your vehicle so it starts and drives the way it should.
The used computer is in — and the car is dead.
- Cranks but will not runThe used ECM or PCM is in, the engine spins, but the immobilizer does not recognize the module — so it never fires.
- "Needs programming"Your mechanic or the parts seller told you the used computer has to be programmed, and nobody local would touch it.
- Security light, no startDash lights up, security or key light stays on, and the car acts like it does not know its own keys.
- Wrong personalityThe car runs but shifts wrong, reads the wrong mileage, or throws codes — the donor software does not match your vehicle.
Match it, program it, prove it.
First we verify the used module is actually a correct match for your vehicle — part number, hardware version, and application. A near-miss part number is the single most common reason a used-computer swap fails, and catching it before programming saves you a second trip to the salvage yard.
Then we take one of two honest routes. If your original module is still readable, we clone it: your software, VIN, immobilizer data, and learned settings are copied onto the used module, and the car sees the computer it has always had. If the original is dead or gone, we program the used module from scratch: manufacturer software for your exact VIN, then immobilizer registration so your keys work. Either way, the job is finished only when the vehicle starts, drives, and scans clean — not when the software bar hits 100%.
We do this across domestic, Asian, and European platforms — engine computers (ECM/PCM), body control modules (BCM), and transmission modules included. If your situation is a key or immobilizer problem rather than a module problem, we will tell you that instead of selling you programming you do not need.
Will a used ECM or PCM from a junkyard work in my car?
Usually yes — if the part number matches and the module is healthy, a used ECM, PCM, or BCM can absolutely go back into service. What it will not do is simply plug in and run. The used computer still carries the donor vehicle's software, VIN, and immobilizer pairing, so it has to be programmed or cloned to your car first. We verify the part is a correct match before any programming starts, because a wrong-part-number module is the most common reason a used-computer job fails.
My mechanic installed a used PCM and now the car won't start. Why?
That is the expected result, not a botched job: the used PCM is still married to the donor car. Its immobilizer pairing does not recognize your keys, so the engine cranks but will not run — or will not crank at all. The fix is programming: we either clone your old module's identity onto the used one or rewrite the used module with the correct software for your VIN and re-register it to your immobilizer. Have the car towed in or drive it in if it runs, and bring the old module if you still have it.
What's the difference between cloning my old module and programming the used one?
Cloning copies everything from your original module — software, VIN, immobilizer data, learned settings — onto the used replacement, so the car sees the same computer it always had. It is the cleanest route when your old module is still readable. Programming rewrites the used module from scratch with the manufacturer's software for your VIN and then registers it to your immobilizer — the route when the original is dead, missing, or corrupted. We pick the route your situation actually allows, and tell you which one and why.
Do I need to bring my old ECM or BCM?
Bring it if you have it. A readable original module lets us clone, which preserves your VIN, immobilizer pairing, and learned settings exactly and is usually the fastest, most reliable route. If the old module is gone or completely dead, we can still program the used one to your vehicle — it just takes the from-scratch route. Either way, also bring your keys and proof of ownership.
Can you program my used module at my house, or do I have to come in?
Used-module programming for vehicle owners is done at our shop, 4715 N Stahl Park, Suite 105, San Antonio, TX 78217, in-shop and by appointment only — we do not dispatch mobile service to vehicle owners. If the car will not start, have it towed in for your appointment. Repair shops and vehicle owners can also use our mail-in bench service for module-only work (a trade-track service open to both).
The shop that says yes to the junkyard computer.
Owners bring used-module jobs to our San Antonio shop from Boerne, New Braunfels, Schertz, Converse, Helotes, Cibolo, Seguin, Selma, Universal City, Live Oak, Castroville, Floresville, Pleasanton, San Marcos and as far out as Kerrville — usually after being told no somewhere else. Because the car often will not start, many arrive by tow truck; call ahead so the appointment is ready when it lands. Vehicle owners are served in-shop, by appointment, at 4715 N Stahl Park, Suite 105, San Antonio, TX 78217. We do not dispatch mobile service to vehicle owners. We do not serve Austin.
Book an in-shop appointment.
Tell us the year, make, model, and which module you bought — and whether you still have the old one. We will confirm the part match before you make the trip.