EDIT: UPDATE 2-7-09 -- Added wiring instructions for 1996 & 1997 PCMs

The wiring instructions linked to BELOW are intended to be used with 3800 Series 2 Supercharged (L67) and NON-Supercharged (L36) engines using either manual transmissions or 4T60-E automatics and the 1996 OBD-2 PCM swapped into Fieros.

http://www.gmtuners.com/fil...PCM_Fiero_wiring.pdf

The compatible PCM service number that these wiring instructions should work with is as follows:

16211539


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The wiring instructions linked to BELOW are intended to be used with 3800 Series 2 Supercharged (L67) and NON-Supercharged (L36) engines using either manual transmissions (L36 or L67), 4T60-E (L36 only), or 4T65-E (L67 only) automatics and the 1997 OBD-2 PCM swapped into Fieros.

http://www.gmtuners.com/fil...PCM_Fiero_wiring.pdf

The compatible PCM service number that these wiring instructions should work with is as follows:

16227797


-----------------------------------------------------------------------------------------------------------

The wiring instructions linked to BELOW are intended to be used with 3800 Series 2 Supercharged engines using either manual transmissions or 4T65-E automatics and 1998-2001 OBD-2 computers swapped into Fieros.

http://www.gmtuners.com/fil...o_L67_PCM_wiring.pdf

Compatible PCM service numbers that these wiring instructions should work with are as follows:

16236757
09356741
09357034
09361735
09374997
09380717

These PCMs are found in various GM car applications but must be reprogrammed with Grand Prix GTP L67 software to be compatible with my wiring instructions. I can provide OBD-2 PCM reprogramming services for these computers. If you have any questions, please feel free to PM or email me.

If you are having trouble downloading the files linked to above, you can go to the main file download page on my website here: http://www.gmtuners.com/files/index.htm

-ryan

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5+ years on this same swap -- NO engine or transmission failures...

Custom GM OBD1 & OBD2 Tuning | Engine Conversions & more | www.gmtuners.com

[This message has been edited by Darth Fiero (edited 02-07-2009).]

Big Thanks as usual!

Wow, now those are wiring instructions I can understand! I understand that much easier than looking at two seperate wiring diagrams and trying to mesh them together.

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'88 GT- 257rwhp 319rwft/lbs 12.74@106.2mph 1/4 mile
www.gmtuners.com

Very nice. Thanx. I was surprised to find that I hadn't already given you a +.

Ryan:
Great info to have and thanks again for another thoughtful post.
Because of the 2006 4T65eHD used on my swap we had to use a 2003 GTP PCM. The wiring is similar but not identical. Have you ever tried doing a swap with the 03 PCM? It was the last year before the switchover to the ETC computer and the new transmisson control scheme. Anyone trying to do a series III powertrain ( w auto trans) or a change over to series II controls is unfortunately locked in to using the 2003 PCM. Thats the only PCM that will shift the 04-07 autos.

[This message has been edited by Dennis LaGrua (edited 08-05-2008).]

i figured this would be for you dwayne

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1987 Fiero GT built by my brother, merlot566jka, 3500 LX9 from 06 Malibu, WOT-TECH.com 1280 grind stage 3 cam, LS6 valve springs, 1227730 ECM conversion, Darrel Morse solid aluminum cradle mounts, Truleo headers modified to fit the 3500, 36# inectors, 70mm 4.3 throttle body adapted to 3500 intake, ported heads, upper and lower intakes, lightly polished, tcemotorsports.com crank trigger wheel, CenterForce dual friction clutch, Flowtech Afterburner muffler, 2.5" piping, cat deleted, EGR deleted, SinisterPerformance tuning, C6 Corvette exhaust tips. projected to be 35 MPG with a guesstimate of 250 hp to the wheels

Nice!

Saved to desktop.

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Thinking about dropping the L67 from my gp into a Fiero.
12.466 @ 114.15 INTENSE S1X/ZZP IC/TOG Headers

Ryan,

I currently have my setup as OBDI with the chip you program for me. I would like to be able to plug in some of the engine monitors available out there, but they don't work with OBDI. The car seems to run well, but do you feel that there would be any advantange to go to OBDII? I am runnng the Fiero 4 speed manual.

I am considering it.
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" DRIVE IT LIKE YOU LOVE IT"

[This message has been edited by ohio86se (edited 08-05-2008).]

Ohio; The advantage to going OBD2 is that you'll have far better and more precise fueling control. For instance OBD1 is "Batch Fire" while OBD2 is MPFI. Also as far as I know, tuning software vendors are no longer doing any program upgrades for OBD1.

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87GT - 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles
87GT - 3.4L Turbocharged engine, modified TH125H
" I'M ON THE LOOSE WITHOUT THE JUICE "

Thanks Darth! I am just now getting to this point. Any suggestions on whether to do the harness before or after the engine is in?

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'86 GTFB, white, auto -Project Turbo, want 12's or better.
'86 SE V6, red, auto, aeropackage --want some parts?
purchased both Mar 17, 07. Neither running. Both 99.9% complete. May sell SE.

quote Originally posted by Dennis LaGrua: Ohio; The advantage to going OBD2 is that you'll have far better and more precise fueling control. For instance OBD1 is "Batch Fire" while OBD2 is MPFI. Also as far as I know, tuning software vendors are no longer doing any program upgrades for OBD1.

Not true. Both OBD1 and OBD2 system used on the 3800 engines are Sequential Fire Injection. Batch fire wasn't used on the 3.8 since 1985, IIRC. Since then all computers used on these engines have employed Sequential fire injection.

The only real advantage the OBD2 systems have over the 94-95 OBD-1 systems at this point is the fact that the OBD2 unit can control a 4T65-E trans, and the OBD1 cannot. Also there are many neat new aftermarket gauges and devices that can show live scan data that only work with OBD2 systems. There are some other minor advantages the OBD2 system has over OBD1 but in reality, there isn't much else that is different. The one big advantage that OBD1 computers have over OBD2 currently is the fact we can emulate, or tune in real-time with the OBD1 computers since they have removable chips. But I am sure in time that this ability will become available for OBD2 computers as well.

Also, Dennis, are you aware there were still "older style" PCMs used on 2004-2005 3800 Series 2 Supercharged applications, such as those that came in the Impalas and Monte Carlos? These computers look identical to the 1998-later generation PCMs and I believe would have also worked with your transmission. These computers were set up to work with cable-op throttle bodies, just like your 03 unit.

quote Originally posted by Darth Fiero: Not true. Both OBD1 and OBD2 system used on the 3800 engines are Sequential Fire Injection. Batch fire wasn't used on the 3.8 since 1985, IIRC. Since then all computers used on these engines have employed Sequential fire injection. The only real advantage the OBD2 systems have over the 94-95 OBD-1 systems at this point is the fact that the OBD2 unit can control a 4T65-E trans, and the OBD1 cannot. Also there are many neat new aftermarket gauges and devices that can show live scan data that only work with OBD2 systems. There are some other minor advantages the OBD2 system has over OBD1 but in reality, there isn't much else that is different. The one big advantage that OBD1 computers have over OBD2 currently is the fact we can emulate, or tune in real-time with the OBD1 computers since they have removable chips. But I am sure in time that this ability will become available for OBD2 computers as well. Also, Dennis, are you aware there were still "older style" PCMs used on 2004-2005 3800 Series 2 Supercharged applications, such as those that came in the Impalas and Monte Carlos? These computers look identical to the 1998-later generation PCMs and I believe would have also worked with your transmission. These computers were set up to work with cable-op throttle bodies, just like your 03 unit.

I may be mistaken on the batch fire with OBD1 but I can safely say that pre 03 ECMs will not shift the 03-07 4T65eHD's. The PCM on Winkies 3800SC series 2 swap for instance was from an 05 Impala and was exactly the same PCM number as the 03 unit in my swap. Do an evaluation of the PCM schematic on the 03-07 transmissons and you will see that the signals used to shift it and the transmisson control elements are different. I am fairly certain that all later series II engines 03-05 use the same PCM. that originated in 03.

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87GT - 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles
87GT - 3.4L Turbocharged engine, modified TH125H
" I'M ON THE LOOSE WITHOUT THE JUICE "

quote Originally posted by Dennis LaGrua: I may be mistaken on the batch fire with OBD1 but I can safely say that pre 03 ECMs will not shift the 03-07 4T65eHD's. The PCM on Winkies 3800SC series 2 swap for instance was from an 05 Impala and was exactly the same PCM number as the 03 unit in my swap. Do an evaluation of the PCM schematic on the 03-07 transmissons and you will see that the signals used to shift it and the transmisson control elements are different. I am fairly certain that all later series II engines 03-05 use the same PCM. that originated in 03.

You are correct on the transmission differences. According to Dave over at TripleEdgePerformance, GM changed the design of the PCS and other pressure control elements in the transmission so they operate differently than previous models. So in that instance you are correct that you would need an 03 or newer PCM if you were going to use an 03 or newer 4T65E transmission.

Sweet, now I can try wiring it myself instead of trying to figure out the two seperate pin-outs, and paying at least $450 to get it done.
Ryan you are a real help to the Fiero community.

thanks Ryan.

What I was looking into a real time gauge that will display engine data, but if that is the only advantange to go to OBDII I don't feel it would be worth it.

I plan on staying with the manual tranny on my 86 which I am very happy with. In my plans I will be going with an E-automatic and a built up 3800SC II in an 88 Fiero.

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" DRIVE IT LIKE YOU LOVE IT"

I'm guessing this won't work for a 97 GTP L67 ECM......... soo close, but yet so far. -Jason

ecm service number 16227797 What do I need to fix this, an newer ecm and harness?

[This message has been edited by Fierofreak00 (edited 08-06-2008).]

quote Originally posted by Fierofreak00: I'm guessing this won't work for a 97 GTP L67 ECM......... soo close, but yet so far. -Jason ecm service number 16227797 What do I need to fix this, an newer ecm and harness?

The pinout instructions I posted won't work for the 1997 PCM. And I have no immediate plans to put together a sheet for the 97 PCM at this time because it is not a very popular computer. But what you can do is get ahold of the factory pinout diagrams for your 97 PCM and then compare those with the instructions I provided. The terminology should be the same (same device names and such). The only real difference you will find is the 97 PCM used very few terminals for sensor grounds and just spliced these wires together in the engine compartment; whereas the later computers used a separate ground wire for almost every sensor. So you will need to take that into account when looking at my wiring instructions. But as far as making connections from the 97 PCM harness to the Fiero, those shouldn't be much different at all (if any) other than the pin locations at the PCM.

-OR- you could just get a newer PCM and harness and then just use my instructions.

-ryan

Ryan, what ever happened to the dozens of diagrams and pinouts you had on your site?

I was wondering the same thing.. But now I think I have all I need Thanks!

quote Originally posted by Darth Fiero: -OR- you could just get a newer PCM and harness and then just use my instructions. -ryan

As easy as it is to play games with the pcm pins, might as well just repin the connector.

I am looking for the conversion diagram on CGP, there is a JPG with all of the conversions required, and IIRC 99% of those are just evap/fuel differences.

POSSIBLE CORRECTION on your wiring chart:
clear connector
Pin 22 A/C request signal in to C203 Fiero A/C request signal out. The Fieros A/C request signal is 12V while the Grand Prix PCM is expecting a 5V input to turn on the A/C. The connection is correct but as above I believe that the Grand Prix A/C request signal level that the PCM expects to see is 5V and not 12V. This connection requires a voltage regulator spliced into the circuit. Putting a 12V request to the GTP PCM might harm it and will certainly trigger and A/C request signal out of range code.
Am I right about this??

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87GT - 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles
87GT - 3.4L Turbocharged engine, modified TH125H
" I'M ON THE LOOSE WITHOUT THE JUICE "

quote Originally posted by Dennis LaGrua: Am I right about this??

I dont remember the specifics of my AC wiring, but I know I did not alter the voltage, and I do not have any problems or get any SES codes.

If you really wanted to alter the voltage, just get a 7805 voltage regulator. They can be had for pennys online, or if you are in a hurry, radioshack stocks them for $3. You need only connect 12v to one pin, ground to another, and the third will output 5v. I really dont think there is a need though.

quote Originally posted by Dennis LaGrua: POSSIBLE CORRECTION on your wiring chart: clear connector Pin 22 A/C request signal in to C203 Fiero A/C request signal out. The Fieros A/C request signal is 12V while the Grand Prix PCM is expecting a 5V input to turn on the A/C. The connection is correct but as above I believe that the Grand Prix A/C request signal level that the PCM expects to see is 5V and not 12V. This connection requires a voltage regulator spliced into the circuit. Putting a 12V request to the GTP PCM might harm it and will certainly trigger and A/C request signal out of range code. Am I right about this??

Not quite. I've been wiring my 3800 swaps like this since I've started using the OBD2 PCMs and they don't seem to care. Never got any "out of range" codes (which I don't even think exist for this circuit in the programming) and the A/C has always worked fine.

Thanks for the instructions...now maybe people can build their own harnesses.

Ryan - You flashed my ECM a few months back, and after some problems with my wiring i need to back over it all. How close should my wiring be, with me using the 4T65E-HD trans? Everything else is the same with your wiring diagrams. (99 motor, obd2)

Blake

Ryan I just wanted to say thanks a bunch for all your help. It would have taken me a lot longer to get this done if it wasnt for your help. The car is just about done. Here is a short video I made. Everyone keep in mind this is the first time in over a year that the car came out of the garge on its own power. Amazing!!

http://www.youtube.com/watch?v=RrmoUsYzigw

quote Originally posted by 85sliverGT: Ryan - You flashed my ECM a few months back, and after some problems with my wiring i need to back over it all. How close should my wiring be, with me using the 4T65E-HD trans? Everything else is the same with your wiring diagrams. (99 motor, obd2) Blake

Blake, you should be aware that my wiring instructions were put together taking into consideration the minor wiring differences over the 4 model year PCMs the instructions work for. Not all cars/PCMs used the same terminals. Examples in this can be found in the sensor 5 volt reference and ground outputs supplied by the PCM. When in doubt, consult the service manual for the model year of computer/engine you are working with. But having said that, the wiring instructions I posted will work fine with any 1998-2001 3800 SC PCM running my custom programming. If you have a specific question or problem, shoot me an email and I would be happy to help you.

-ryan

BUMP: UPDATE 2-7-09 -- Added wiring instructions for 1996 & 1997 PCMs

Just uploaded diagrams for 3800 Series 2 SC and NON-SC Fiero swaps using 94-95 3800 OBD-1 PCMs to my website. More info in this thread: https://www.fiero.nl/forum/Forum2/HTML/098364.html

Darth. You've really posted some good info here and have done a service to the forum. One of the claims in my post in this thread about the A/C request signal was incorrect. As you pointed out, the A/C request to the PCM works with a 12V input which brings up another point. Could the A/C request perhaps rely on a varying voltage from +5V to +12V that is somehow tied into the GTP temperature controller? I'm doing some checking on this now and geting conflicting info. Even some F/T air technicians that I've asked don't know for sure.
Another thing that you touched upon was that the same PCM used on the 2003 Grand Prix was also used on series II engines up until 2005 in the Bonnneville and Impala. When GM changed 4T65eHD trans designs in 03 it was the only PCM that could shift it.
PCM #12583826 is being used for engine management on my 2006 series III w changes. Have you tried using this PCM? It seems similar to earlier units with the exception of the output signal waveforms to the trans.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
87GT - 3.4L Turbocharged engine, modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

quote Originally posted by Dennis LaGrua: Darth. You've really posted some good info here and have done a service to the forum. One of the claims in my post in this thread about the A/C request signal was incorrect. As you pointed out, the A/C request to the PCM works with a 12V input which brings up another point. Could the A/C request perhaps rely on a varying voltage from +5V to +12V that is somehow tied into the GTP temperature controller? I'm doing some checking on this now and geting conflicting info. Even some F/T air technicians that I've asked don't know for sure.

In every 3800 Fiero swap I have done using the PCMs I am talking about in this thread, a 12v + signal has always been used and has worked to tell the PCM that A/C operation is requested. In addition, every GM car I have worked on that had a seperate A/C request wire going to the PCM has always supplied the PCM with 12v + voltage on this circuit when A/C operation is requested. The only exceptions I have ever seen were in applications where the A/C request was transmitted to the PCM along the serial data line (saw this in Buick Reatta applications and some others).

Now, that doesn't mean a 5v + signal wouldn't work. The PCM might just be looking to that input to go "high" from its resting state of "low" voltage to determine whether or not A/C operation is requested. I haven't tested this myself because I have had no reason to -- the 12v + signal works.

quote Another thing that you touched upon was that the same PCM used on the 2003 Grand Prix was also used on series II engines up until 2005 in the Bonnneville and Impala. When GM changed 4T65eHD trans designs in 03 it was the only PCM that could shift it. PCM #12583826 is being used for engine management on my 2006 series III w changes. Have you tried using this PCM? It seems similar to earlier units with the exception of the output signal waveforms to the trans.

I have not ever had a need to use an 03-up PCM on a 3800 swap I have done; mainly because I have never used an 03+ 4T65E in a 3800 swap I have done which would require this. I have tuned the 12583826 PCMs in other (non-Fiero) applications, so I have worked with it. Just never had the need to use it in a Fiero swap yet. And FYI, the last model year GM used this "older" style OBD-2 PCM with 3800 SC applications using a cable-op throttle body was 2005. I did some tuning on an '05 Monte Carlo with the L67 last year and that car had a 12583827 PCM. Very similar to the 12583826 PCM you are using.

Any particular reason why you ask if I ever used it?

-ryan

I think this needs a sticky.

quote Originally posted by Darth Fiero: EDIT: UPDATE 2-7-09 -- Added wiring instructions for 1996 & 1997 PCMs The wiring instructions linked to BELOW are intended to be used with 3800 Series 2 Supercharged (L67) and NON-Supercharged (L36) engines using either manual transmissions or 4T60-E automatics and the 1996 OBD-2 PCM swapped into Fieros. http://www.gmtuners.com/fil...PCM_Fiero_wiring.pdf The compatible PCM service number that these wiring instructions should work with is as follows: 16211539

Darth, can I convince you to make an account and post these on FieroWiki.com? If not is it okay if I put them up over there? Good stuff to have around. Thanks.

quote Originally posted by MickeyAsh: Darth, can I convince you to make an account and post these on FieroWiki.com? If not is it okay if I put them up over there? Good stuff to have around. Thanks.

Joined under the username "Sinister Performance". Where/in what section did you want me to post these?

quote I have not ever had a need to use an 03-up PCM on a 3800 swap I have done; mainly because I have never used an 03+ 4T65E in a 3800 swap I have done which would require this. I have tuned the 12583826 PCMs in other (non-Fiero) applications, so I have worked with it. Just never had the need to use it in a Fiero swap yet. And FYI, the last model year GM used this "older" style OBD-2 PCM with 3800 SC applications using a cable-op throttle body was 2005. I did some tuning on an '05 Monte Carlo with the L67 last year and that car had a 12583827 PCM. Very similar to the 12583826 PCM you are using. Any particular reason why you ask if I ever used it?

-ryan



Ryan: Just wondering what your take on the 12583826 was. Having worked with it I was wondering if you found it harder to reprogram. On mine the VATS was successfully disabled but I've heard stories of guys unable to disable the VATS on it. With some tips from a couple of guys here, including yourself, and the LS1 MAF table imported (your input also) I've found this PCM easy to work with. The program seems heavily MAF based like the LT1 system is.
Not to beat the A/C request signal issue to death but go into ALLdata and look in the HVAC section for a 2003 Grand Prix. The GTP A/C system uses an ambient air temperature sensor #12054621. There is also a cabin temperature sensor # 10272757 which appears to output the same. These sensors puts out a 5V signal and if I am not mistaken are part of the A/C control module.This would seem to indicate that the GTP A/C control is under some kind of varying inputs from the cabin. Yes the +12V request signal will work. I've tried it and it does turn the system on full blast as you say. However, I was looking to hook up the the regulation and control of cabin temperature as the grand prix has it That included these two sensors taking part in a way yet undetermined. On the Fiero, A/C control is crude- you just mix in some hot air to get the right temperature. On the GTP, sensors via the PCM provide automatic control and it may be doing it on the request pipeline. Sorry to stray off topic but its a feature that I'm trying to solve, understand how it works and once I do I will hook it up.


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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
87GT - 3.4L Turbocharged engine, modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

[This message has been edited by Dennis LaGrua (edited 02-16-2009).]

quote Originally posted by Darth Fiero: Joined under the username "Sinister Performance". Where/in what section did you want me to post these?

Under downloads> wiring diagrams.

Thanks!

[This message has been edited by MickeyAsh (edited 02-16-2009).]