Straight answers about module programming
The questions we are asked most often about automotive module programming, answered the way we would answer them on the phone. If your question is not here, call (404) 812-8951 and ask it.
Do I have to tow my car to the dealer to get a module programmed?
For most module programming, no. Auto Module Programming brings dealer-level programming equipment to the vehicle anywhere in metro Atlanta. Programming a module by VIN needs three things — the manufacturer’s own software, a J2534 pass-thru interface that speaks to it, and a power supply that holds the vehicle’s voltage steady for the whole session. None of the three is fixed to a building.
Auto Module Programming runs the manufacturer software by VIN: FDRS for Ford and Lincoln, SPS2 and ACDelco TDS for Chevrolet, GMC, Cadillac and Buick, wiTECH for Chrysler, Dodge, Jeep and RAM, Techstream and TIS for Toyota and Lexus, i-HDS for Honda and Acura, CONSULT III Plus for Nissan and Infiniti, GDS and KDS for Hyundai, Kia and Genesis, ISTA and AOS for BMW and MINI, XENTRY for Mercedes-Benz including Sprinter and Smart, ODIS Service for Volkswagen, Audi and Porsche, MDARS for Mazda, SSM4 for Subaru and MUT-III for Mitsubishi. The calibration file a module receives in your driveway is the same file it would receive in a dealer bay, pulled for your VIN.
What genuinely still sends a vehicle to a dealer is narrower than most people are told: a procedure that needs a tool the manufacturer sells to its own network only, or a repair that is not a programming job at all. We will tell you which of those applies to your vehicle before you pay for a tow, and we will tell you on the phone if the VIN makes it obvious.
The comparison that matters is not mobile against dealer. It is whether the procedure needs an online OEM session and whether the vehicle’s power can be held stable while it runs — and both of those happen at the vehicle.
Is mobile module programming as good as the dealer?
It is the same operation with the same software. Auto Module Programming runs the manufacturer procedure by VIN at the vehicle, in your driveway or your shop, across metro Atlanta. The risk in any programming session is voltage. A module that loses supply partway through a flash can be left unable to boot, and that is a failure mode no software setting prevents.
That is why a Midtronics PSC-550S at 55 A or PSC-700S at 70 A goes on the vehicle before a session starts and stays on it until the session ends. A programming supply is not a battery charger — it holds a fixed voltage under the load the module draws while it writes, which a charger does not do and a healthy battery alone will not do for a long session.
The documentation is the other half of the answer. Every job ends with a work order you keep: codes from every module before and after, the VIN, the original and donor part numbers where a module was replaced or cloned, and the operation performed. If a shop cannot hand you a pre-scan and a post-scan, you have no record of what changed on your vehicle.
Where a manufacturer requires an online session to authorise a calibration, we run it. Where a procedure calls for a specific drive cycle or relearn afterwards, we run that too, rather than handing the vehicle back with the flash written and the adaptation missing.
Is it safe to have my car’s computer programmed in a driveway instead of a shop?
Yes, and the reason is specific rather than reassuring. The one real hazard in a programming session is the vehicle losing voltage partway through a write, which can leave a module unable to boot. A building does not prevent that. A regulated supply does.
Auto Module Programming puts a regulated programming supply on the vehicle before the session starts and leaves it there until the session ends, in a driveway exactly as in a bay — the same equipment, and for the same reason, a dealer uses in its own workshop.
What a driveway does need is somewhere the vehicle can sit undisturbed for the length of the procedure, and enough access to work at the OBD-II port and, where the module has to come out, at the module itself. A flat parking space is enough. We work across metro Atlanta — Buckhead, Marietta, Lawrenceville, Decatur and Brookhaven.
What a driveway cannot supply is a reason to skip anything. The pre-scan, the post-scan and the paperwork are identical to the ones a bay would produce.
Can I put a junkyard or used ECM in my car without programming it?
No — a used ECM arrives carrying the donor vehicle’s VIN, its option configuration and, on most vehicles built in the last twenty years, its immobilizer data. The vehicle you install it in will reject it — typically as a crank-no-start, because the immobilizer does not recognise a key it was never taught, and usually with VIN-mismatch codes alongside it.
Even where a vehicle starts, the configuration is wrong. The controller has been told which options the donor had, not which options yours has, so transmission shift behaviour, emissions readiness monitors and the anti-theft chain all run against the wrong data. It is the kind of fault that gets misdiagnosed for months.
There are two routes that work, and which one applies depends on whether your original module still reads:
- 1
Program the used module to your vehicle by VIN
Your VIN and option configuration are written to the used module on the manufacturer’s software, and the immobilizer is taught the module and the keys under NASTF VSP credentialing, against proof that the vehicle is yours. This is the route when your original module is gone or unreadable. VIN writing and module adaptation runs $300–$800.
- 2
Clone your original onto the used module
Where your original still holds readable data, we read it — over OBD-II, or directly on the bench when the module no longer answers the vehicle — EEPROM and MCU with an Autel XP400 Pro, or flash, EEPROM and MCU with a VVDI Prog — and write it to the donor. The donor becomes your module: your VIN, your configuration, your theft-deterrent data. Cloning to a matched donor runs $250–$450.
I found a used ECM for my Chevy at a salvage yard. What do I check before I buy it?
Check the full part number on the controller label against yours, and on GM check the hardware revision too. Auto Module Programming will do that against your VIN before you buy, at no charge — a GM controller that misses on either will take your data and then run against the wrong build.
The controllers we are asked about are the E38, E39, E67, E78, E80, E82, E84, E90 and E92 engine controllers, and the T87 and T87A on the transmission side. Two things travel with a used one and both have to be dealt with: the RPO configuration, which is the list of options the donor vehicle was built with, and the VTD theft-deterrent data, which is what stops your key starting a controller that was taught someone else’s.
That second one is why a used GM controller usually produces a crank-no-start rather than a running engine with odd behaviour. The immobilizer is doing its job.
If your original still reads, the better route is to clone it onto the donor: your VIN, your RPO and your VTD data go across, the network accepts it as the module it already knew, and no security relearn is needed. If it does not read, the donor is programmed to your VIN on SPS2 and the theft-deterrent setup runs afterwards under NASTF VSP credentialing.
Either route ends the same way: a CASE relearn — the crankshaft variation relearn GM requires after an engine controller is replaced or reprogrammed. Skip it and the vehicle can set a misfire code with nothing mechanically wrong with it.
One more, on the transmission side: if the vehicle pairs an engine controller with a T87 or T87A, changing one without addressing the other is how a vehicle ends up running and shifting badly at the same time. Tell us both part numbers when you call.
Does the used module have to be the exact same part number?
For cloning, yes. The donor has to match on the full OEM part number, and on some platforms on the hardware revision as well. A module that looks identical and carries a different revision will take the data and then behave incorrectly, which is worse than a module that refuses it outright.
Send us the part number off a used module and your VIN before you buy it, and we will tell you whether it matches — at no charge. A donor that misses on the part number or the hardware revision is the most common reason a customer-supplied module cannot be used, and it is cheaper to find out before the money is spent.
Where no matched donor exists, programming a new module by VIN is the route instead, and we quote that before proceeding rather than after. Cloning is not guaranteed on modules damaged by water, fire, short circuit, corrosion or prior tampering — if the memory will not read, there is nothing to copy.
What does U0100 mean, and does it mean my ECM is dead?
U0100 means a module stopped answering on the network. It does not mean the module failed, and Auto Module Programming does not replace a module on a U-code alone. The code records silence, and silence has several causes — of which a dead computer is only one, and in our experience not the most common one.
A lost-communication code is as often a corroded ground or a chafed CAN wire as it is a failed controller — on a Jeep Grand Cherokee, a Silverado or anything else. The same applies to U0101, U0121 and U0140 — the transmission, ABS and body control variants of the same message. All four get the same treatment, and the order below is what separates them.
What it costs to put right forks on that answer, which is why the diagnosis comes first. An on-site diagnostic runs $185–$300. If the fault is a ground, a connector or a CAN wire, the repair is the wiring — no module, no programming. If the module genuinely failed, cloning to a matched donor runs $250–$450 and programming a replacement by VIN runs $300–$800. Nobody can quote you honestly before that fork is settled.
The order matters, because each step rules out the causes that would make the next one misleading:
- 1
Scan every module, not just the one that set the code
Codes stored, pending and freeze-frame data recorded. A single module reporting lost communication and a whole segment of the network reporting it are different faults with different causes.
- 2
Test the charging system under load
Battery, alternator and charging system tested under load rather than at a resting voltage reading. Low system voltage produces communication faults that look exactly like a failed module.
- 3
Check the feeds — fuses, relays, both supplies
Permanent and ignition-switched feeds to the module, and the fuses and relays in between. A module with no power cannot answer, and it will set the same code as one that has failed.
- 4
Voltage-drop test the grounds
Module grounds are tested under load, not inspected. A ground that passes a visual check and fails under load is a recurring cause of intermittent communication faults and is invisible to a scan tool.
- 5
Measure CAN High and CAN Low
Resistance and signal are measured on CAN High and CAN Low. This is the step that decides whether you are buying a computer or repairing a wire, and skipping it is how the wrong part gets sold.
- 6
Check bulletins and calibration for that VIN
Applicable manufacturer bulletins and calibration updates. Where an OEM bulletin calls for a reflash or an updated calibration, that is the repair — and replacing the module without it reproduces the fault.
What is NASTF VSP credentialing, and how do I check a shop actually has it?
NASTF is the National Automotive Service Task Force, and its Vehicle Security Professional registry is how an independent technician gets authorized access to manufacturers’ own security systems — key programming, immobilizer resets, PIN and code retrieval. It is worth understanding because it is the thing that separates a shop that can legitimately do security work from one that cannot.
What it is not: NASTF does not hand out security codes and does not program vehicles. It verifies the technician — a registered business, commercial insurance, a background check and multi-factor authentication on every manufacturer platform — and then the manufacturer decides what that verified identity may access. The credential is an identity, not a key.
How to check a shop has it: ask. A credentialed technician can produce their VSP status on request, and Auto Module Programming will do that where a job requires it. What you should be wary of is the reverse — a shop that offers to bypass an immobilizer, or to supply a key without asking who owns the vehicle. Any legitimate security job starts with proof of ownership: your ID, the registration or title, and a signed authorization. A shop that skips that step is telling you something.
We do not publish our credential number on this page, and no shop should. It is a security identifier, and printing it in public would be careless with the exact thing it exists to protect.
My car will not start and I cannot move it. Can you still help?
Yes — that is the ordinary case for us, not the exception. A vehicle that will not start is the one that cannot be driven to a shop, and towing it before anyone has looked at it means paying for transport to find out what the fault is.
We come to the vehicle with the diagnostic equipment and the regulated programming supply, so the visit that identifies the fault is usually the visit that repairs it. Where the module has to come out and go on the bench, we tell you that on site and quote it before it leaves.
An on-site diagnostic anywhere in metro Atlanta runs $185–$300 and covers the full protocol: every module scanned, the charging system tested under load, feeds and grounds checked, and CAN integrity measured. You get the result whether or not the answer turns out to be a module — including when the answer is that the fault is mechanical and programming will not fix it.
We work within 40 miles of Brookhaven — Atlanta, Buckhead, Marietta, Lawrenceville and Decatur — and travel to Savannah, Pooler, Brunswick, Augusta, Macon and Columbus by arrangement. Call (404) 812-8951 with the year, make, model and the symptom, and we will tell you on the phone whether this is something we can settle at the vehicle.
Ask us about your vehicle
Year, make, model and the symptom is usually enough for us to tell you whether this is a programming job, a wiring fault or something else entirely — before you pay for a tow. See what we carry and hold access to, what an on-site diagnostic covers, or why a transmission flash is only half the job.
Auto Module Programming answers on (404) 812-8951, Monday to Sunday, 8:00 AM to 7:00 PM
Call (404) 812-8951