LT1-LT4 Modifications 1993-97 Gen II Small Block V8

OBD 1-2 connector swap

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Old 10-24-2008, 11:38 PM
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Default OBD 1-2 connector swap

I have a 95 Caprice with an OBD2 computer and an OBD1 connector. What pins do I swap to the OBD2 (going to get from the junkyard) connector to make it work correctly?
Old 10-25-2008, 12:00 AM
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Why are you doing this if you dont mind me asking?.
Old 10-25-2008, 12:44 AM
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i was just looking at this earlier, here is what you need to do to use the obd2 connector wth an obd1 scanner but i would assume its the same for using the computer itself?

Old 10-25-2008, 10:22 AM
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I have an ELM327 that has a OBD2 plug on it and my car is a 95 with an OBD2 computer and a OBD1 plug. I cant seem to find another cable for it (OBD1 style) so I figured Id swap out my connector and be able to finish tuning my car.
Old 10-25-2008, 11:45 AM
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why would your car have an obd1 connector with an obd2 computer? i thought all 95s were exactly opposite of that. i know my 95 has an obd 2 connector and the computer is obd1
Old 10-25-2008, 09:26 PM
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Originally Posted by 1995blacktattop
why would your car have an obd1 connector with an obd2 computer? i thought all 95s were exactly opposite of that. i know my 95 has an obd 2 connector and the computer is obd1
exactly, its called a OBD 1.5
Old 11-02-2008, 07:44 PM
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Ok well I put a known OBD 1 comp in and am ready to tune it. Now I just have to make my car work with the OBD 2 connector my scanner/tuner came with. Is this even possible make it work. I'm an electrician so wires don't worry me. Just tell me what to connect to what and Ill be set. Any ideas???
Old 11-03-2008, 09:09 AM
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buy an adapter cable. my car is an obd2 car (1996 Trans Am) with an obd1 conversion. obd1 is great for ease of tuning but obd2 is great for diagnosing. i can access the obd2 with the factory DLC using my Tech II or plug in my akm cable to tune in obd1. hope that helps! when i did the conversion, i didnt convert my connector or re-pin it.
Old 11-03-2008, 09:15 AM
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The ELM327 won't talk OBD1. So you can't use it with an OBD1 computer.

If you stick an OBDII computer in the car, you'll need to bring the PCM wire Blue 7 to the diagnostic connector (that's the OBDII data pin). What I did was to use the OBD1 ALDL pin "B" (Mode Select, I believe it's Blue 20) and move it to the Blue 7 location. You'd stick that in to Pin 2 on the OBDII connector. You'll need to disable codes for crank sensor and rear O2 sensors though.

I converted my 94Z to OBDII for a time, went back to OBD1 eventually.
Old 11-03-2008, 09:16 AM
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The OBD2 Connector uses Pins 2, 4, 5, 16.
2- Serial Data Wire(Tune/Diagnostic Wire)
4,5- Grounds
16- Constant Power off of Battery

I have an OBD2 PCM & Engine, and had to wire the Connector just like that to get it to work, and it works without a problem.
The wiring was even inplace for the #2, just was never used cause I didn't have an OBDII PCM & Engine.
Old 11-03-2008, 09:31 AM
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IF your doing an obd1 swap your going to need more then just the pcm. You also need to get a obd1 knock sensor. Once you have both of those item all you need from there is to get cable with the obd2 style connector and your good to go. If your a 95 You just need to a get a cable with a obd2 style connector and thats it since your still have a obd1 pcm.
Old 11-03-2008, 05:41 PM
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Yeah, I hear there are no real benefits to an OBD2 computer over the OBD1. and that OBD1 is much easier to tune. I'm guessing I should just get me a OBD1 computer connection and ditch the ELM.



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