On some obd vehicles pre1996 it would usually flash code on the dash u but on obd ll cant do it/////////// the second link shows how to do the gm 82-95 obd code retrival
Standard interfaces
ALDL
Main article: ALDL
GM's ALDL (Assembly Line Diagnostic Link) is sometimes referred as a predecessor to, or a manufacturer's proprietary version of, an OBD-I diagnostic. This interface was made in different varieties and changed with powertrain control modules (aka PCM, ECM, ECU). Different versions had slight differences in pin-outs and data rates. Earlier versions used 160 bit/s, while later versions went up to 8192 bit/s and used bi-directional communications to the PCM.[7][8]
OBD-I
The regulatory intent of OBD-I was to encourage auto manufacturers to design reliable emission control systems that remain effective for the vehicle's "useful life".[citation needed] The Diagnostic Trouble Codes (DTCs) of OBD-I vehicles can usually be found without an expensive 'scan tool'. Each manufacturer used their own diagnostic link connector (DLC), DLC location, DTC definitions, and procedure to read the DTCs from the vehicle. DTCs from OBD-I cars are often read through the blinking patterns of the 'Check Engine Light' (CEL) or 'Service Engine Soon' (SES) light. By connecting certain pins of the diagnostic connector, the 'Check Engine' light will blink out a two-digit number that corresponds to a specific error condition. The DTCs of some OBD-I cars are interpreted in different ways, however. Cadillac (gasoline) fuel-injected vehicles are equipped with actual on-board diagnostics, providing trouble codes, actuator tests and sensor data through the new digital Electronic Climate Control display. Holding down 'Off' and 'Warmer' for several seconds activates the diagnostic mode without the need for an external scan tool. Some Honda engine computers are equipped with LEDs that light up in a specific pattern to indicate the DTC. General Motors, some 1989-1995 Ford vehicles (DCL), and some 1989-1995 Toyota/Lexus vehicles have a live sensor data stream available, however, many other OBD-I equipped vehicles do not. OBD-I vehicles have fewer DTCs available than for OBD-II equipped vehicles.
OBD-1.5
OBD 1.5 refers to a partial implementation of OBD-II which General Motors used on some vehicles in 1994 and 1995. (GM did not use the term OBD 1.5 in the documentation for these vehicles; they simply have an OBD and an OBD-II section in the service manual.)
For example, the 94-95 Corvettes have one post-catalyst oxygen sensor (although they have two catalytic converters), and have a subset of the OBD-II codes implemented. For a 1994 Corvette the implemented OBD-II codes are P0116-P0118, P0131-P0135, P0151-P0155, P0158, P0160-P0161, P0171-P0175, P0420, P1114-P1115, P1133, P1153 and P1158.[9]
This hybrid system was present on the GM H-body cars in 94-95, W-body cars (Buick Regal, Chevrolet Lumina ('95 only), Chevrolet Monte Carlo ('95 only), Pontiac Grand Prix, Oldsmobile Cutlass Supreme) in 94-95, L-body (Chevrolet Beretta/Corsica) in 94-95, Y-body (Chevrolet Corvette) in 94-95, on the F-body (Chevrolet Camaro and Pontiac Firebird) in 95 and on the J-Body (Chevrolet Cavalier and Pontiac Sunfire) and N-Body (Buick Skylark, Oldsmobile Achieva, Pontiac Grand Am) in 95 and 96 and also on '94-'95 Saab vehicles with the naturally aspirated 2.3.
The pinout for the ALDL connection on these cars is as follows:
For ALDL connections, pin 9 is the data stream, pins 4 and 5 are ground, and pin 16 is 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.[10]
An OBD 1.5 has also been used on Mitsubishi cars of '95 '97 vintage,[citation needed] some[which?] 1995 Volkswagen VR6's[citation needed] and in the Ford Scorpio since 95.[11]
on some obd vehicles pre1996 it would usually flash code on the dash u but on obd ll cant do it
On board diagnostics Yahoo Web Search
Jeff is right obd2 96 and newer will need a scan tool.
What year an make vehicle ? Before 1996 you can do that on some make vehicles , not all ,GM cars mostly ! 1996 an above need scanner for all vehicle makes !
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