Editing On-board diagnostics (section)

===OBD-1.5===

OBD 1.5 refers to a partial implementation of OBD-II which [[General Motors]] used on some vehicles in 1994, 1995 & 1996 (GM did not use the term OBD 1.5 in the documentation for these vehicles — they simply had an OBD and an OBD-II section in the service manual).

For example, the 1994–1995 model year Corvettes have one post-catalyst [[oxygen sensor]] (although they have two [[catalytic converter]]s), and have a subset of the OBD-II codes implemented.<ref>{{cite book | title=1994 Corvette Service Manual, Book 2 | publisher = General Motors Corporation |date=December 1993 | pages = 6E3–A-166 : 6E3–A-223}}</ref>

This hybrid system was present on GM [[General Motors B platform|B-body]] cars (the Chevrolet Caprice, Impala, and Buick Roadmaster) for 1994–1995 model years, [[General Motors H platform (1986)|H-body]] cars for 1994–1995, [[General Motors W platform|W-body]] cars (Buick Regal, Chevrolet Lumina) for 1995 only, Chevrolet Monte Carlo (1995 only), Pontiac Grand Prix, Oldsmobile Cutlass Supreme (for 1994–1995), [[General Motors L platform|L-body]] (Chevrolet Beretta/Corsica) for 1994–1995, [[General Motors Y platform|Y-body]] (Chevrolet Corvette) for 1994–1995, on the [[General Motors F platform|F-body]] (Chevrolet Camaro and Pontiac Firebird) for 1995 and on the [[General Motors J platform|J-Body]] (Chevrolet Cavalier and Pontiac Sunfire) and [[General Motors N platform|N-Body]] (Buick Skylark, Oldsmobile Achieva, Pontiac Grand Am) for 1995 and 1996 and also for North American delivered 1994–1995 [[Saab Automobile|Saab]] vehicles with the naturally aspirated 2.3.

The pinout for the ALDL connection on these cars is as follows:
{| class="wikitable" style="text-align:center"
| 1 || 2 || 3 || 4 || 5 || 6 || 7 || 8
|-
| 9 || 10 || 11 || 12 || 13 || 14 || 15 ||16
|}

For ALDL connections, pin 9 is the data stream, pins 4 and 5 are ground, and pin 16 is the battery voltage.

An OBD 1.5 compatible scan tool is required to read codes generated by OBD 1.5.

Additional vehicle-specific diagnostic and control circuits are also available on this connector. For instance, on the Corvette there are interfaces for the Class 2 serial data stream from the PCM, the CCM diagnostic terminal, the radio data stream, the airbag system, the selective ride control system, the low tire pressure warning system, and the passive keyless entry system.<ref>{{cite book | title=1994 Corvette Service Manual, Book 2 | publisher = General Motors Corporation | date = Dec 1993 | pages = 6E3–A–11}}</ref>

An OBD 1.5 has also been used in the [[Ford Scorpio]] since 95.<ref>{{cite web |url=http://www.fordscorpio.co.uk/star.htm |title=EEC IV Code Reader: For 2.9L 12 Valve & Early Tdi |website=Ford Scorpio |location=UK |date=2006-01-14 |access-date=2024-06-02}}</ref>