OBD1 diagnostics · Corvette 1982–1995
Your Corvette has been talking since it left Bowling Green.Now you can listen.
VetteALDL is a cable, a driver and a Windows app built together for the ALDL port of 1982–1995 Corvettes. Live data with normal ranges, trouble codes of every module in plain language, guided tests at the car and output tests – free, with no ads and no tracking.
Windows 10 and 11 · donationware – free to use · no ads, no tracking
F4 57 01 00 B4
Checksum ✓
The engine computer's reply, 8 times a second. Hover a highlighted byte to decode it.
- engine computers
- model years
- modules
- languages
- trackers
What it does
A scanner that speaks C4.
Built for these cars only: the data layouts, the body computer link-up and the output tests of every OBD1 Corvette, checked against GM's own Tech 1.
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.
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.
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.
Recordings – play every drive back
Every connection is recorded automatically. Play it back later on a big screen, through every page of the app.
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.
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.
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.
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.
Screens
Night-cluster look, readable on the garage floor.
Designed together
Cable, driver and app – so the only unknown is the car.
The cable
An FTDI FT232R with an open-collector driver: it pulls the data line low exactly like the engine computer does and never pushes against it. Protected up to 24 V on the data pin.
Build it yourselfThe driver
FTDI's signed driver is installed for you. For cables with fake FTDI chips, our own VetteFTDI driver talks to the chip directly – no driver lottery, 1–2 ms latency.
The app
Finds the cable, the driver and your engine computer by itself, checks that the numbers make physical sense, then shows you the car.
All features
Coverage
Every OBD1 Corvette, 1982 to 1995.
One definition per engine computer, curated from community work and checked against GM's data stream specifications and the Tech 1.
| Years | Engine | ECM (mask) | Baud | Modules | Output tests |
|---|---|---|---|---|---|
| 1982 | L83 5.7 Cross-Fire InjectionC3 (Y) | A062 | 160 | ECM | – |
| 1984 | L83 5.7 Cross-Fire InjectionC4 (Y) | A063 | 160 | ECM | – |
| 1985 | L98 5.7 TPIC4 (Y) | $1F | 160 | ECM | – |
| 1986 | L98 5.7 TPI (MAF)C4 (Y) | $32 | 160 | ECM | – |
| 1987–1988 | L98 5.7 TPI (MAF)C4 (Y) | $32B | 160 | ECM | – |
| 1989 | L98 5.7 TPI (MAF)C4 (Y) | $6E | 8192 | ECM | 8 |
| 1990–1991 | L98 5.7 TPI (speed density)C4 (Y) | $8D | 8192 | ECM CCM SIR | 25 |
| 1990–1992 | LT5 5.7 DOHC (ZR-1)C4 (Y) | $8E | 8192 | ECM CCM SIR | 25 |
| 1992–1993 | LT1 5.7C4 (Y) | $DA2 | 8192 | ECM CCM ABS SIR | 26 |
| 1993–1995 | LT5 5.7 DOHC (ZR-1)C4 (Y) | $F0 | 8192 | ECM CCM | – |
| 1994–1995 | LT1 5.7C4 (Y) | $EE | 8192 | ECM | 14 |
1982 is the last C3, with Cross-Fire Injection; there was no 1983 model year. CCM = body computer, ABS = ABS/ASR, SIR = air bag. 1995 cars have the 16-pin connector – same data, pin 9.
Built in the garage
Tested on a real 1992 LT1 – and checked against the factory tool.
VetteALDL started with a C4 brought back to life in a home garage and a pile of cables and programs that didn't work. Every release since has been shaped by what the car actually said: garage tests with the engine running, byte-by-byte recordings, and an emulated GM Tech 1 as the reference for data lists, trouble codes and output tests.
It is free to use, with voluntary donations of any amount. The more cars it sees, the better it gets – that is why the app has a button that sends the recording of a session to us.
- Every trouble-code bit of the 1989–93 engine computers and the body computer checked against GM's Tech 1
- Output tests send the exact frames the Tech 1 sends
- Every byte we transmit is checked on the wire as it comes back
- The ECM layout is verified while you read: a wrong selection is spotted and corrected by itself
Download
Free for every C4 owner.
Donationware: no account, no e-mail, no ads. Donate any amount you like – or nothing at all; every download gets the same app.