What is ALDL?

ALDL is an acronym for Assembly Line Data Link. It is a one-wire interface used to connect the engine control unit (ECU) to diagnostic computer systems for diagnosis and troubleshooting.

1G DSMs use a version of the ALDL interface. All 1G dataloggers are designed to connect to the interface and interpret the information. 2G vehicles do not use ALDL, they use OBD-II (see below).

DSM enthusiasts did not recognize the ALDL interface for what it was until fairly recently. Because of this the GM hobbyists have much more information available on how ALDL works. There may be differences between the GM ALDL format and the DSM ALDL format since ALDL is not a formalized standard. For more information on ALDL, see these links:

• the free datalogger site
• Andy Whittaker's ECU page
• the Tech Edge GM ALDL interface page
• AKM Cables' very useful GM ALDL information page
• the results of this Google search