THE OBD1.5 to OBD1 Conversion Thread

[robertisaar]

i'm waiting for the black PCM plug still, but this is how far i've gotten on the guide. it is fairly if not all the way complete. when i get the plug(shipment was rescheduled for today), i can further refine it if necessary.

feel free to criticize or otherwise.

its in .doc, but if you need it in some other form, contact me and i'll see what i can do.

EDIT: DOC removed, latest version of the guide in this post. if it gets updated it will ALWAYS be here.

EDIT: Newest version of Guide Date: 9/16/2009.

EDIT: Added new starter pack to this post dated 12/21/09. a lot of little misc changes, notabley added a fuel economy guage to the DF ADX.

[IsaacHayes]

It opens in open office, so linux folks should be ok.

[robertisaar]

It opens in open office, so linux folks should be ok.

i would hope so, i made it in openoffice, i just saved it as a doc since its probably more accessible to everyone that way.

[bszopi]

Since you did it in OpenOffice, why didn't you just make it a PDF? Also, I'll probably end up making this an actual article, and link to a location to download the actual guide. I just skimmed through it really quick, but it looks pretty good so far. One thing you probably need to say is that people need to verify their pin-outs, as I am not 100% sure that all PCMs through the OBD1.5 years had the same pinouts. They probably do, but I would rather there be a disclaimer telling them to verify...

[IsaacHayes]

I have L body diagrams so I can compare when it's done and let you know.

[robertisaar]

Since you did it in OpenOffice, why didn't you just make it a PDF? Also, I'll probably end up making this an actual article, and link to a location to download the actual guide. I just skimmed through it really quick, but it looks pretty good so far. One thing you probably need to say is that people need to verify their pin-outs, as I am not 100% sure that all PCMs through the OBD1.5 years had the same pinouts. They probably do, but I would rather there be a disclaimer telling them to verify...

i mentioned that i guaranteed it for the monte but for the rest i'll have to run through them..

[ForcedFirebird]

Most excellent writeup.

[robertisaar]

still needs a little tweaking, and i may just add the repinnning tables for every variant if needed. one question though: 94-95 V6 F-Bodies use the same PCM as the rest of us obd1.5 3100 cars, but will the tranny controls work for them too? i don't know enough about the 4l60e. i imagine it would work fine with a t5 though...

[3400-95-Modified]

I tried to do it this way, and I gave up and went OBDII, granted that may not be as easy for you, but it was easier for me. I couldn't get sensors to read properly so the car wouldn't run right, I used sockets from a old 95 computer and soldered on the 3 plugs needed for a OBD1 ecm from a Buick IIRC because it had 4t60e controls... I spent a few months on it and then just gave up.

Hope your turnout is better.

[IsaacHayes]

The buick A-body is an oddball, hopefully this one will have more luck since it doesn't use the weird MAF only setup. This one is more common.

[3400-95-Modified]

Maf wasn't my issue... I had problems with my coolant temp sensor grounds, my cam position sensor and so on... I was receiving a maf signal IIRC, just all those other f-up's such as the coolant sensor not reading right (-40) made it run super rich for no reason... and I couldn't figure out the other grounds to get the cam position sensor to work. I had problems with adapting the ECM to the harness that was there, why I don't know, and hopefully your adapter works better, but I just didn't have luck with something like that.

[IsaacHayes]

Right, didn't say the MAF was your issue, but I'm saying that A-Body setup was so different than all other GM vehicles that who knows what wacky grounds and shared 5v references they had going on. Hell it had a MAF built into the TB or something weird like that too. The UIM was unique too IIRC in how it bolted to the TB.

[robertisaar]

Maf wasn't my issue... I had problems with my coolant temp sensor grounds, my cam position sensor and so on... I was receiving a maf signal IIRC, just all those other f-up's such as the coolant sensor not reading right (-40) made it run super rich for no reason... and I couldn't figure out the other grounds to get the cam position sensor to work. I had problems with adapting the ECM to the harness that was there, why I don't know, and hopefully your adapter works better, but I just didn't have luck with something like that.

luckily i don't have to deal with a cam sensor, just the 3X crank sensor...

trust me, if there is a way to do it, i will find out how...

[robertisaar]

how many fans do L and N Bodies have? according to my alldata, theres only 1 relay. are there 2 fans that run on the 1 relay or is there just 1 fan?

i'm asking because i thought of a very interesting way to show how differently the W, L, and N Bodies are pinned. those are the only obd1.5 3100s, right?

Details to come soon...

[robertisaar]

here it is: my big ass interchange of repinning.... or something like that.

i'll work it into my complete guide in a little bit.

there are some very small changes between the pinnings for the W, N, and L bodies. they should be fairly easy to see though.

and as a disclaimer: assuming L and N bodies are grounded EXACTLY the same way as a W, then this section is complete. i don't have a N or L to inspect to verify, and alldata doesn't have a whole lot of info about it either. so take it for what its worth.

EDIT: and i don't think i can do any automatic F-Bodies because from what i can infer, they have a pressure control solenoid for line pressure, something this PCM has no way of controlling, however, if someone was interested in running this PCM on their manual car, i can try and make it happen...

ANOTHER EDIT: i checked the pinouts for a 95 Monte Carlo, 95 Beretta, and a 95 Grand Am. i don't really see GM changing the pinouts from 94 to 95, but i'll check anyway(meant for brad, i thought you were talking about something else earlier)

FINAL EDIT: XLS removed, it was pointless since i have all of the different bodylines pinouts in the guide, post 1