obdII to obdI conversion issues
Thread Starter
Launching!
Joined: Sep 2009
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From: 5280
obdII to obdI conversion issues Hey fellas, ok so i have a 97 z28, had an electrical **** up that caused a full on melting of most of the wires in the engine harness and fried the pcm, so i rebuilt the car, but decided to go to obdI, so i ordered a full obdI computer, and engine harness. guys on here told me it will plug right into my dash harness which it did, i had my tuner come down and put a baseline on it and it wont connect to the ALDL port. all gauges are working but car wont fire, just cranks. but not being able to connect to it obviously isnt going to get me anywhere.
i have checked all grounds from the pcm and all are good and have a good connection, but there might be something else i need to do. do i need to get a different aldl port?
thanks for the help guys
i have checked all grounds from the pcm and all are good and have a good connection, but there might be something else i need to do. do i need to get a different aldl port?
thanks for the help guys
Last edited by xrambbc; Jun 7, 2012 at 09:50 PM.
I hate wiring issues. Sounds like you did everything right. Usually when converting obd2 to obd1 all you have to change is the pcm and knock sensor. Load a the appropriate tune and done. Hope you find the issue soon.
1) I would refer to shbox.com. Confirm that the ALDL port is pinned out correctly. It may just be a misplaced wire or ground.
2) As for the no crank but no start. Confirm the usual suspects... fuel pressure to rule out fuel delivery. Then check ignition. I suspect there may be an issue there causing the coil not to fire or ICM not to do its job.
I know it isn't much but this is where I would start. Good luck!
2) As for the no crank but no start. Confirm the usual suspects... fuel pressure to rule out fuel delivery. Then check ignition. I suspect there may be an issue there causing the coil not to fire or ICM not to do its job.
I know it isn't much but this is where I would start. Good luck!
Thread Starter
Launching!
Joined: Sep 2009
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From: 5280
ok well i dont have my tuner here to hook up to it, but i did find out it is not priming the fule pump, and really the pump isnt working when key is on or in crank position. hooked up a 12v wire to the prime connector and sure enough fuel at the rails, i checked the relay under the dash, i am doin some wire testing now. just dont under stand. question though, i have a obdII scanner will it hook up even though its converted but still has the pin outs for obdII?
Would have been way easier to have installed the correct year harness 97 and order the Obd1 pcm and knock sensor from WWW.madtuner.com
Thread Starter
Launching!
Joined: Sep 2009
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From: 5280
well i got the pcm and harness untouched for 150 bucks local, so i thought hell just plug it in and go. everything plugged right in so i figured all was good. guess not. but what would cause the other harness to work but not this one?
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Thread Starter
Launching!
Joined: Sep 2009
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From: 5280
nope never, all the gauges are reading properly, im putting the rest of the stuff on tomorrow and ill try starting it again.
but why is the key not priming the pump? never had that issue before. the only thing i dont have hooked up right now is the alternator, but that cant be the issue, i have a bettery charger on it at all times, im waiting for my madman low mount kit to get here. everything else is hooked up.
but why is the key not priming the pump? never had that issue before. the only thing i dont have hooked up right now is the alternator, but that cant be the issue, i have a bettery charger on it at all times, im waiting for my madman low mount kit to get here. everything else is hooked up.
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Verdad Gallardo Dead Pump? Bad Relay? Attach manual fuel pressure gauge to valve on back of fuel rail and determine where you are at. Normal pressure is around 42 PSI.
From what I gather, you are using an OBDII style connector, but with an OBDI pcm. I did some research, If you are using an OBDII code reader it will not work. You need an OBDI reader with the appropriate OBDII style connector. Don't forget also you need the 12v adapter for OBDI readers.
The appropriate cable is sold at http://www.tunercat.com/, you will need USB/ALDL-2.
From what I gather, you are using an OBDII style connector, but with an OBDI pcm. I did some research, If you are using an OBDII code reader it will not work. You need an OBDI reader with the appropriate OBDII style connector. Don't forget also you need the 12v adapter for OBDI readers.
The appropriate cable is sold at http://www.tunercat.com/, you will need USB/ALDL-2.
I did this conversion only with the 97 harness and a 94 PCM. You need a tuning cable for a 1995 LT1. It has the correct ALDL plug for under the dash and is compatible with the OBD1 PCM. As far as the differences between the OBD1 and OBD2 harnesses, as far as I know the only differences are: Lack of rear O2 sensors and the lack of a Crankshaft Position Sensor. All I did was swapped my PCM to the 94 OBD1 PCM, and swapped the Knock Sensor to the 94 LT1 Knock Sensor. What transmission do you have and was the PCM flashed for the same tranny? Also, I suggest sending the PCM to madtuner to get socketed because when you burn out a chip (which you will) then it becomes a 5 minute fix rather than a 1 or 2 week fix as long as you have spare chips. I hope this helps.
ok well i dont have my tuner here to hook up to it, but i did find out it is not priming the fule pump, and really the pump isnt working when key is on or in crank position. hooked up a 12v wire to the prime connector and sure enough fuel at the rails, i checked the relay under the dash, i am doin some wire testing now. just dont under stand. question though, i have a obdII scanner will it hook up even though its converted but still has the pin outs for obdII?
Thread Starter
Launching!
Joined: Sep 2009
Posts: 240
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From: 5280
yea my tuner has tunercats, it wouldnt hook up. he knows i went to obdI. but the fuel pump works when i put 12v's to the prime connector in the engine bay. i dont understand what the problem is i changed nothing else but unplugged the old harness, plugged in the new one. i installed all the obdI opti and knock sensor.
There is no "OBD1" Opti. I have the same exact opti on my car that was on my 97 LT1. 93-94 and 95-97 Opti's are different. The opti wasnt different because of the PCM, it was different because the older opti's are non-vented and the drive shaft is different. If you installed an opti from 93-94, you need to take it off and install an opti from 95-97.
Thread Starter
Launching!
Joined: Sep 2009
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From: 5280
well i got the motor out of a 95 firebird, so i left it all alone put my heads, intake and cam in it and called it good, it has the opti that has the short style connector, not like the one on my 97. is there any difference in signal with the older ones compared to the newer ones?
Thread Starter
Launching!
Joined: Sep 2009
Posts: 240
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From: 5280
ok so should i just put a 97 harness back in it with the 95 pcm or leave it alone and figure out the fuel pump? i dont want these issues in the future. i can get a new 97/m6 harness for pretty cheap if its gonna be easier on me.
Ok, I've got the EXACT same problem,...a 97 Z28 that I got without a harness/motor/trans,....found a 95 harness/motor/trans and a OBDI computer,...all installed and looking so good.
It has fired a couple times but when it would'nt anymore I swapped the computer into my 95 Z28 and found out it's dead there, won't fire the 95.
So now in the 97 no fuel pump prime with turning the key "on",...but fuel pump primes with a jumper wire to the prime connector underhood.??!?!?!?
It has fired a couple times but when it would'nt anymore I swapped the computer into my 95 Z28 and found out it's dead there, won't fire the 95.
So now in the 97 no fuel pump prime with turning the key "on",...but fuel pump primes with a jumper wire to the prime connector underhood.??!?!?!?
I have a 97 SS. I did not change my harness. I use a knock sensor from a 94 Z28 and a PCM from a 94 Z28. I use a 95 LT1 Tuning Cable and I use tunercats, tunerpro RT and datamaster. I have had this setup for 2 years on a 411 RWHP 357, and now a 442 RWHP 383 and I have zero issues. Do you have a stock fuel pump or an upgrade? If you upgraded, did you get the racetronix hotwire kit?
I think the problem resides in the HARNESS swap.
If you get on Shbox's site you can see the different pin outs on the connector faces of the harness(not the PCM, the harness),...here's the link to what I'm talking about.
http://shbox.com/1/harness_connector_faces.htm
(note: the links to the different connector faces are available on a menu near the bottom of this link)
They are different year to year.
THIS is where our problems are, in the harness connections.
I thought I changed mine correctly and like I said, at one time the set up allowed me to fire up my car and run it a couple times,...then it ran like **** a couple times and then last night I find the PCM is non working,...I know because I swapped it into my good running 95 Z28 and it would'nt fire that car at all.
I'm wondering if I did something that is frying the PCM?
I've got another OBDI computer and I'll try that one,...pretty sure we need to figure out the fuel relay wiring, at least.
Those weird noises you sometimes hear, that's me pulling out my hair,...f**k the receding hairline,...I'm pulling it out?!.
If you get on Shbox's site you can see the different pin outs on the connector faces of the harness(not the PCM, the harness),...here's the link to what I'm talking about.
http://shbox.com/1/harness_connector_faces.htm
(note: the links to the different connector faces are available on a menu near the bottom of this link)
They are different year to year.
THIS is where our problems are, in the harness connections.
I thought I changed mine correctly and like I said, at one time the set up allowed me to fire up my car and run it a couple times,...then it ran like **** a couple times and then last night I find the PCM is non working,...I know because I swapped it into my good running 95 Z28 and it would'nt fire that car at all.
I'm wondering if I did something that is frying the PCM?
I've got another OBDI computer and I'll try that one,...pretty sure we need to figure out the fuel relay wiring, at least.
Those weird noises you sometimes hear, that's me pulling out my hair,...f**k the receding hairline,...I'm pulling it out?!.
Last edited by TIIMuch; Aug 24, 2012 at 03:08 PM.
