Frequently Asked Question

Last Updated 2 years ago



The ALDU1 is a datalogger designed to work with OBD I GM vehicles.

The ALDU1 is compatible with the CABL1 and the CABL2, which are interface cables that connect to GM OBD I and OBD II vehicle respectively.

The ALDU1 can be purchased by itself, or as a combo with either the CABL1 or CABL2.

CABL1 is used for ~88-94 GM OBD1 vehicles with a rectangular ALDL connector like this:

female ALDL connector

CABL2 is used only on 95 (and some late-year 94) vehicles that still speak ALDL but have the D shaped “OBD2-style” connector like this:

Female OBD2 port

It can be interfaced with many pieces of software, including TunerPro.

Pinouts and Wiring

In the event you need to build a custom cable, use the following pin outs for the RJ45 connector:




This is the 86-94 original ALDL connector:

ALDL 12pin 86-94


  • pin A is connected to RJ45 pin 1
  • pin B is connected to RJ45 pin 2
  • pin E and pin M are connected to RJ45 pin 3
  • pin G is connected to RJ45 pin 4
  • other pins are not connected

This is the late model ALDL connector used in 1995:

ALDL 16pin 95


  • Pins 4 and 5 are connected to RJ45 pin 1
  • Pin 13 is connected to RJ45 pin 2
  • Pin 9 is connected to RJ45 pin 3
  • Pin 16 is connected to RJ45 pin 4
  • Pin 2 is connected to RJ45 pin 5
  • Pin 10 is connected to RJ45 pin 6
  • Pin 14 is connected to RJ45 pin 7
  • Pin 6 is connected to RJ45 pin 8

How to Buy


Test Procedure

The first step towards determining if your ALDU1 is working correctly is to look at the USB side. Before you continue, you should have verified USB connectivity and you will need to know which COM port your cable is using. Take a look at the USB troubleshooting guide if you have any questions or concerns here.

You will need to have TunerPro RT version 5.0 or later installed.

Test procedure:

  1. Start TunerPro RT with your cable plugged into your computer but unplugged from the vehicle.
  2. Load a valid XDF / ADS-ADX combination for your vehicle
  3. Go to Tools … Preferences and select “Use Plug-in” for Interface type. Then make sure “TunerPro Data Acquisition I/O Interface” is selected. Next, select “Configure Plug-in Component” Then make sure “Standard Serial” is selected and the COM port shown matches the COM port of your cable. image
  4. Finally, click the “Test For Valid Interface Using Settings” to perform a test on the cable.

If your cable fails the above test, it will almost certainly need to come back to us for repair. If it passes the above test, the hardware has passed a basic minimal test.

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