The engine computer, the body computer, ABS/ASR and the air bag module – read, explained and tested from one app. Start with the car; the technical depth is one click away.
Dashboard · Live data
Live data with normal ranges
Every value your engine computer sends, decoded into plain units – with the range a healthy C4 shows for what the engine is doing right now.
Gauges for the numbers you glance at, a full live-data table for everything else. VetteALDL knows whether the engine is off, cranking, warming up or idling warm: values just outside the normal range turn amber, clearly out-of-spec values turn red.
Dashboard gauges, value tiles with minimum and maximum, strip charts
A short explanation for every parameter – what it is and what moves it
Dashboard of a warm-idling 1992 LT1: gauges for engine speed, vehicle speed, coolant, MAP, throttle and battery, and sensor tiles with min/max and sparklines.
Trouble codes
Trouble codes of every module
Engine computer, body computer (CCM), ABS/ASR and air bag – read, explained in plain language and cleared module by module.
Each code has an owner-friendly title and a short explanation. Behind More: symptoms, likely causes, a numbered diagnostic path, specifications and what to watch in the live data.
Read codes now – the button every scanner has
Current and history codes of the body computer and the air bag module
ABS codes with vehicle speed and ignition cycles
Clearing per module, always after a confirmation
More
Every code bit of the 1989, 1990–91, ZR-1 and 1992–93 engine computers and of the 1992–93 body computer was checked against GM's Tech 1 running in VetteALDL's emulator. Bits the Tech 1 shows only as a number are shown too, so a set bit is never hidden.
Trouble codes read from the car, with code 44 opened: what the ECM detected, the symptoms and the likely causes, most common first.
LiveDoctor · Guided tests
LiveDoctor and guided tests
A second pair of eyes on the live data: it spots the contradictions a single gauge can't show – and walks you through the classic C4 faults at the car.
LiveDoctor watches all values together – an idle that is too high while the idle air valve is almost closed, an O2 sensor that stopped switching, a charging voltage out of range – and says what to check next.
The guided tests advance from the live data step by step, then compare the result with the service manual and GM's Tech 1 data and name the next checks. They run on a played-back recording too.
LiveDoctor watching the live data and explaining a high idle with a nearly closed IAC and lean fuel trims, with the next checks to make.
Recordings
Recordings – play every drive back
Every connection is recorded automatically. Play it back later on a big screen, through every page of the app.
Pause, jump and play at up to 20× speed; output tests and cleared codes are marked on the time line. A cable that drops out is reopened by itself and the gap shows on the time line. Share a recording and it plays byte for byte on another computer.
Recordings are decoded again with the newest definitions
Kept for three months – copy a folder to keep it longer
Opens support bundles and bus recordings from other computers
Recordings page playing back an earlier session, with the list of recorded connections and the playback bar.
Virtual Tech 1 · factory behaviour
Virtual Tech 1 – the factory tool, bit for bit
An emulator of GM's hand-held Tech 1 scanner that runs the original cartridge software unchanged – the same menus, data lists, trouble-code logic and output tests a dealer technician used.
VetteALDL emulates the Tech 1's hardware – the HD6303 processor, cartridge memory, 4×16 display, keypad and ALDL port – and executes GM's own program instruction by instruction. Nothing is re-created or guessed: what the Virtual Tech 1 sends to your car and how it reads the answer is exactly what the factory tool does.
That is why it matters. Every other page of VetteALDL was checked against it: data-list layouts, the bit behind every trouble code, the frames of every output test and the air bag protocol were taken from the factory software running here – so the app's plain-language pages behave like the factory tool, too.
Import cartridge images you own – VetteALDL contains no GM or Vetronix software
81-93 POWERTRAIN: engine computers of 1989–93 Corvettes (8192 baud), L98, LT1 and ZR-1
88-93 BODY and the Y-body cartridge: body computer data list, codes and dash tests
Runs against the simulator or your car, with a log of every frame the Tech 1 sends and every answer
Keyboard or on-screen keypad; no ageing scanner, cartridge or power cable needed
More
The 1994–96 applications need cartridge parts that are not in the known images, and 1982–88 engines talk at 160 baud, which the Virtual Tech 1 cannot connect to yet – VetteALDL's own pages cover those cars.
Virtual Tech 1 running GM's own 81-93 POWERTRAIN cartridge software against the simulated 1992 LT1: the engine data list on the emulated 4x16 display and every frame the Tech 1 sends and the car answers.
Output tests
Output tests – the Tech 1's own commands
Switch the cooling fans, A/C, AIR pump, canister purge, lamps and idle speed from the laptop – with the frames GM's Tech 1 sends.
The commands were recorded from GM's Tech 1 software running in VetteALDL's emulator for every 1989–93 engine computer, including the ZR-1's secondary system. Body computer tests switch warning lamps, relays, chimes and instrument lighting.
Every test says what it does and asks for confirmation
Blocked until the data prove the right car is selected
Run them only with the car parked, the parking brake on and the transmission in P/N
More
Nothing is hidden, everything is guarded: risky functions such as raw frames sit behind an explicit Expert mode with its own warning.
Output tests with an ECM-confirmed cooling fan test running; lamps, relays and expert tests are grouped by system.
Body & switches · 1990–93
Body & switches, seen from above
Doors, hatch, key, lock cylinder, lock buttons, seat belt, lights, rear defogger and the oil level switch – live from the body computer, on a top view of the car.
Operate each switch and watch it change: it gets a check mark once seen in both positions. One that never changes is the suspect – switch, wire or connector. Every change is logged with the time, so an intermittent door switch shows up too.
Body and switches page: door, hatch, key, lock and light switches from the body computer on a top view of the car (driver door open) and the switch test.
ABS / ASR · 1992–93
ABS and traction control
Wheel speeds on a picture of the car, a wheel-sensor and brake-switch test and stored codes with speed and ignition cycles.
Turn a wheel and see which sensor answers; a mismatch warning points at the wheel that disagrees. Pump, ASR and fluid status at a glance; codes can be cleared once the fault is fixed.
Air bag (SIR) page reading the diagnostic module's current and history codes, with the safety notes for working on the system.
Dash diagnostics
Dash diagnostics decoder
1990–96 Corvettes can show module codes on the instrument cluster. VetteALDL shows the jumper for your year, explains the screens and decodes what you read.
Each code comes with causes and checks, and engine codes link to their full diagnostic path. ABS flash codes are decoded too.
1990–93: jumper ALDL pins G and A, key on, engine off
1994–96: pins 12 and 4 of the 16-pin connector
1984–89: never jumper G–A – pin G is the fuel pump circuit there
Dash diagnostics decoder: a code read from the instrument cluster's own diagnostic mode (body computer code 41) explained with causes and checks.
Connection debugger · Bus monitor
When something doesn't talk, it finds out why
Four real measurements – PC and driver, cable on the bench, car with the ignition off, ignition on – end in a conclusion in plain words.
Swapped wires, the wrong pin, a missing ground, fake FTDI chips, a driver that injects garbage, inverted EEPROM lines, a 160 baud car: each has its own finding with the evidence and how to fix it.
Automatic detection of the cable, the driver, your engine computer and its definition
Bus monitor: every frame with time, direction and module; our own bytes echo-checked
Connection details stay in the Tools menu – the car comes first
Connection debugger after all four test steps: the ECM identified with high confidence and a marginal-cable warning with how to fix it.
The cable · rev B
A cable that plays by the ALDL rules
The data line is one wire that every module may only pull low. This cable does exactly that – and survives 12–24 V on the data pin.
Open-collector transmitter, MOSFET-isolated receiver, a genuine FTDI FT232R, a TVS diode for spikes. Every part, every voltage and why it is there are on the cable page.
Cable page with the schematic of the recommended VetteALDL cable: FT232RL module, open-collector transmitter and protected receiver on ALDL pin M.
Languages · Support
Six languages, one support button
English, Polish, German, Spanish, French and Italian – the app, the help and this website.
When something goes wrong, open Sessions & support, add a note and send the session to the VetteALDL team with one button. We replay it byte for byte – that is how the app learns new cars.
