Live engine data
RPM, IAC position, TPS, MAP, coolant temperature and battery voltage, refreshed every second.
WiFi ALDL scanner · GM 1988–1995
OBD1 scanner for your GM truck: see what the computer really says.
A small, read-only WiFi scanner. Plug it into the diagnostic connector, open your phone and watch RPM, fuel mixture, oxygen sensor, temperature and trouble codes live. No apps. No internet. No guessing.
- Read-only: never erases or reprograms
- Runs in your phone's browser
- 1-month warranty
LIVE · demo192.168.4.1
Coolant temp88 °C
O₂ sensor450 mV
LoopClosed
Battery14.0 V
MAP1.3 V
CodesNone
Sample values. On your truck you get the real ones.
The problem
Swapping parts "to see if that's it" gets expensive.
Surging idle, stalling with the A/C on, weak power, poor fuel economy. Without data, the shop tries one part and then another. With this scanner you see what the computer itself reports and walk into the shop with a concrete lead, not a hunch.
What you see
The same data a pro scan tool shows, on the screen you already carry.
Fuel mixture and O₂ sensor
Open or closed loop, fuel trim (INT and BLM) and O₂ signal: you can tell whether it runs rich, lean, or the sensor is dead.
Trouble codes
Stored codes with their meaning, without counting Check Engine flashes or jumping terminals.
Graphs and recording
Record a full drive and review the graphs later. Download the CSV file for your mechanic or to request a reading.
Report vs. factory values
Each system shows as OK, Check or Not enough data, compared with the service-manual ranges. No false alarms.
No apps, no internet
The scanner creates its own WiFi network. Connect, open the browser, done. It works the same on the street, on the highway or in the shop.
Tested on a real truck
It found what nobody could see by eye.
This scanner was born to fix a 1993 GMC Sonoma 2.8 TBI. Three unexplained problems, solved with the data:
Dead oxygen sensor
The computer ran in closed loop only a tenth of the time. With a new sensor it stayed in closed loop almost all the time, with no codes.
Surging with the A/C on
It wasn't the A/C: the speed sensor sent false pulses while the truck was parked. It showed up in the data and was fixed with a resistor that costs pennies.
Lean mixture and knock
Fuel trim was at its limit. It was measured, the injectors were replaced and the trim returned to its normal range.
See it working
This is how it looks on a real truck, while driving.
Videos of the scanner reading the computer of a 1993 GMC Sonoma on the road: live data, tests and solved cases.
How it works
Four steps. Five minutes.
Plug it in
Black lead in hole A and red lead in hole E of the diagnostic connector, under the dash. The blue one goes on M only if your vehicle transmits on M.
Power it
USB cable to a cigarette-lighter charger. Key ON.
Join its WiFi
On your phone, pick the scanner's network (name and password are on your card).
Open the browser
Go to 192.168.4.1 and you're looking at your truck's data.
The wiring is read-only: it never sends anything to the computer, so it can't erase codes or change its programming.
Mini guide · 2 minutes
Does your vehicle have pin E, pin M, both or neither?
Before buying, check which data pins your connector has. That tells you whether the scanner can read it.
- Look at the connector (key OFF). Count from A: A, B, C, D, E on the top row; M is the last one on the bottom row. Does that hole have a metal terminal with a wire? If it's empty or plugged, that pin doesn't exist on your vehicle.
- Measure the ones that do have a wire. Multimeter on DC volts, 20 V range; black probe on A (ground) and red probe on the pin. Key ON. Just touch with the probe, don't force it.
- Compare with the table below.
| What you measure | What it means | Can the scanner read it? |
|---|---|---|
| E fluctuates between about 2 and 3 V | Has pin E: transmits at 160 baud | Yes The normal case for 1988–1993 TBI |
| M near 5 V and E with no wire or at 0 V | Pin M only: transmits at 8192 baud | With M channel Verified on a 1993 Silverado. Message me before buying |
| E and M both active | Has both | Yes We use the one that matches your computer; we confirm it from a photo of its label |
| Neither (no wire, or 0 V with key ON) | No data on the connector, or the key/pin is wrong | Probably not Check the key is ON and send me a photo of the connector and the VIN |
| Either one at 12 V | That hole has another function (for example, the fuel pump on G) | Don't connect Verify the engraved letters |
- On E the computer transmits nonstop: the multimeter averages the pulses, so the reading moves. A changing reading is a good sign; stuck at 0 V is not.
- A steady 5 V on pin M shows it exists, but some connectors have other pins at 5 V; the final proof is the scanner receiving data.
- Values come from our own measurements on real GM trucks and may vary by a few tenths. If in doubt, send me a photo of the connector and the VIN and I'll tell you.
Compatible vehicles
GM TBI fuel-injected, 1988 to 1995.
With a 12-hole diagnostic connector (rectangular, under the dash on the driver's side). Each unit ships already configured for your vehicle.
| Engine | Years |
|---|---|
| 2.8 TBI | 1988–1993 |
| 3.1 TBI | 1991–1994 |
| 4.3 TBI | 1988–1993 |
| 5.0 TBI | 1989–1995 |
| 5.7 TBI | 1989–1995 |
| 7.4 TBI | 1989–1991 |
Not supported Vehicles from 1996 onward (OBD2, 16-pin connector): use an ELM327 scanner for those. Not sure about your vehicle? Ask me before buying and I'll confirm it from a photo of the connector or the computer's label.
Pricing
The scanner and, if you prefer, I read your data for you.
RT-Web Scanner
Ask for the price
Unit configured for your vehicle.
- WiFi scanner with A, E and M leads and a USB cable
- Instructions and a guide to reading the data
- 1-month warranty
- Shipping not included; I generate the courier label for you
Reading Basic
$100 MXN
You record a drive (up to 1,000 rows, about 20 min with the engine running) and I send back a document on the state of your engine.
- What's fine and what to check first
- Delivered within 24 h of payment
Reading Full
$150 MXN
Up to 2,000 rows, about 40 min. Anything longer, or a before-and-after follow-up of a repair, is quoted.
- Codes, systems reviewed and order of tests
- Payment by bank transfer (SPEI); card coming soon
How to pay: by bank transfer (SPEI, Mexico); I send you the details on WhatsApp. Coming soon credit and debit card payments. Shipping is not included: I generate the courier label for you and you only pay its cost.
A reading does not replace an in-person inspection: some mechanical faults (compression, leaks, noises) don't show up in the computer's data. If a physical test is needed, I'll tell you which. If your file is unusable, I'll let you know before charging.
Honest about what it doesn't know
The report only flags "Check" using factory-manual ranges. If there isn't enough data to conclude, it says so and asks for another stretch of driving.
1-month warranty
Sealed, numbered unit. Manufacturing defects: repaired or replaced. If you're not happy, you have 5 business days to return it.
WhatsApp support
A misplaced lead or a phone on the wrong network gets sorted out by message. Direct help from the person who built it and uses it on his own truck.
Frequently asked questions
Before you ask.
Does it work on a Chevrolet S10, GMC Sonoma, Silverado, Blazer, Cheyenne or Suburban?
Yes, if it's a 1988–1995 model with TBI fuel injection and a 12-hole ALDL connector: Chevrolet S10, GMC Sonoma, Blazer and Jimmy, Cheyenne, Silverado and Sierra C/K 1500, and Suburban. What matters is the engine (2.8, 3.1, 4.3, 5.0, 5.7 or 7.4 TBI) and the connector pins, not the truck's name. Send me your model, year and engine and I'll confirm.
What are ALDL and OBD1, and which trucks have them?
ALDL is the diagnostic connector GM used before OBD2 (1996), also called OBD1. Trucks like the S10, Sonoma, Blazer, Jimmy, Cheyenne, Silverado and Suburban have it with TBI injection from 1988 to 1995. It is a rectangular 12-hole connector under the dash.
Can it damage my truck's computer?
It is read-only: it only listens to what the computer already transmits. It sends no commands, erases no codes and reprograms nothing. Just put the leads on A and E, and not on other holes.
Do I need to install an app or have mobile data?
No. The scanner creates its own WiFi network and the page opens in your phone's browser (Chrome) at 192.168.4.1. Your phone may warn that the network "has no internet": choose to stay connected.
Does it work with an iPhone?
Live data shows in any browser. To save files, Chrome on Android works best; send me your model and I'll confirm.
Does it erase trouble codes?
No. It reads them and tells you what they mean. To clear them, disconnect the battery for a few minutes.
Do you reprogram chips or tune the computer?
That is not part of the service. This is scanning and diagnosis only.
What charger do I need?
A 12 V cigarette-lighter to USB charger rated at least 1 A. It is not included; a very weak one can make the scanner reboot.
How do I pay and how does it arrive?
Today you pay by bank transfer (SPEI, Mexico): I send you the details on WhatsApp and we ship once the payment is confirmed. Credit and debit card: coming soon. Shipping is not included and is paid by the customer: I'll happily generate the courier shipping label for you and you only pay its cost; in Rioverde, S.L.P. it can also be handed over in person. Outside Mexico? Message me and we'll work it out.
Start today
Send me your truck's model and year and I'll tell you if it works.
A straight answer, no obligation.