1995 Opel diagnostic strategy change

Up until about 1995, there was one diagnostic lead (ALDL 10-pin plug pin G) for all Opel/Vauxhall systems. In about 1995, the diagnostic lead was divided up, and later models used up to 4 separate K-lines within a 16-pin plug. This was progressively introduced for all vehicles.

The reason for this was that to meet the specifications, each control unit must have an input resistance of 1k ohms on the diagnostic lead, and as these are in parallel on the diagnostic lead reliable connection could not be achieved with more than 10 control units connected. The division into 4 diagnostic lines was made to allow simultaneous communication with linked control units. For example, the engine control unit is one one lead, the transmission control unit is on another, and the ABS control unit is on a third. These separate leads are designated K-lines.

The 16-pin connector pin allocations are:
1 - unoccupied
2 - unoccupied
3 - diagnostic lead (automatic transmission, central door locking, electric sliding roof)
4 - earth
5 - earth
6 - blink code (engine control unit)
7 - diagnostic lead (electric seat, engine control unit)
8 - diagnostic lead (cruise control, TID/MID, ATWS/immobiliser)
9 - unoccupied
10 - unoccupied
11 - unoccupied
12 - diagnostic lead (airbag, ABS)
13 - unoccupied
14 - unoccupied
15 - unoccupied
16 - +12V

Hope this helps someone...
John

 
Received on Mon Oct 13 05:58:23 2003