THE OBD1.5 to OBD1 Conversion Thread

[robertisaar]

<---- FACEPALM

but you have what you want now?

[ForcedFirebird]

^^^facepalm

I DO have the pinouts, but want me some alldata :P

[robertisaar]

Enjoy.

[ForcedFirebird]

You're the man! Thanks again...

I have a 3 ring binder with all the pinouts and notes taken during these travels, just makes everything more uniform (slight OCD).

[robertisaar]

i know the feeling... except i'm documenting things so that I don't forget!

[ForcedFirebird]

Well, I had a warranty call on one of the harness adapters I wrote "A17" but put the wire on "A12" due to bad handwriting on the last one.....

[robertisaar]

i know the feeling on that one.... i'm still trying to get cardana24's harness to work right... for some reason it keeps popping a fuse on a VSS adapter... it's confusing the hell out of me.

[ForcedFirebird]

I check every pin to pin conversion, AND cross-talk. Other words, every pin checked, also gets checked across every single other pin in the series of connectors. Think you may have a short, or maybe it's a different VSS that may have an issue?

[robertisaar]

both Carson and i have checked the whole harness multiple times over... no idea what's going on. i did fix an issue where i had the o2 sensor's ground and signal wires mixed. other than that, it's perfect according to pinout conversions. i'm baffled by it, i'm not sure what's causing it or how, but the VSS adapter uses a GM 4000PPM unit, so i would think that's fine. the fuse that keeps blowing on the VSS adaptor is labeled ignition, which makes about 0 sense...

[robertisaar]

just updated the original post with a new starter pack, has a few extra things in it now, including how to test for and determine the amount of ethanol/water in your fuel and an economy table for the DF ADX.

[robertisaar]

slight update: was thinking about it, and realized that on older ECMs, there was a switch on the brake pedal that would disconnect the TCC by opening the circuit. on our OBD1.5 cars(at least FWD), there is a circuit that goes to the ECM to accomplish the same thing, but there is no direct mechanical or electrical connection from the switch at the pedal to the TCC solenoid itself like there was with the 9396 cars...

basically, all this means is that if you step on the brake with the throttle still applied far enough to keep the TCC locked, it won't disconnect. once you remove enough throttle, it will. this shouldn't be an issue so long as you have reasonable numbers in the tune for TCC Diconnect vs TPS%... if it actually still bothers you enough, i could produce the wiring change necessary to restore it to working like the 9396 expects...

the switch is also tied into the brake lights, but those work fine after the conversion so i'm not sure what to think of it...

another thing: i MAY be getting the stock BIN off of the stock PCM from the 95 MC soon, and although that would be enough to start hacking through it and eventually being able to flash the chip through the ALDL port much like OBD2, i'm not going to hack it, at least not that far. i realized that if a flash gets interrupted, then the PCM is pretty much junk unless you desolder the chips, flash them in a EEPROM burner, stick them back in(preferably in a socket since it COULD happen again), then continue on with your tuning. i'm much happier with the ability to remove a chip, flash it and be done with it in less than 30 seconds than going through that ordeal.

BUT

i SHOULD be able to spot a few major things in the BIN like main spark, VE tables, etc., that could be used in the $DF BINs to better replicate a factory tune. other things could also be found, but would likely require a lot of disassembly and hacking to find.

[robertisaar]

something else: with the 9396, there is an input for coolant level that doesn't exist with the 1.5 PCM. the 94-95 dashes(if they have a low coolant light) control this on their own with no PCM intervention.

lucky for us: this means we can use that input for WB02 since it's looking for a 5V signal on that pin.

[robertisaar]

some more interesting stuff that may or may not apply to anyone reading this(found on TGO http://www.thirdgen.org/techboard/di...27727-ecm.html). even though the parts seem to be impossible to find, maybe someone is better than searching than i am. i did find a few on mouser...

12066132 - terminals
12052924 - seals for the terminals (package of 20 p/n 12048086 seals)
12065877 - Connector 'C' (Green on my Vette)
12065878 - Connector 'D' (brown on my Vette)
12065876 - Connector 'B' (Red on my Vette)
12065875 - Connector 'A' (yellow on my Vette - manual says Yellow or Gray)
12059155 - Header for connectors 'A' and 'B' (header is what is attached to the ECM and what the connector mates to)
12059154 - Header for connectors 'C' and 'D'

[bszopi]

Nice, the PNs for the 7727. But if the price of those are comparable to the others, then you are looking at over $150 (IIRC) in just connector pieces. Seems like grabbing from the junkyard would be a better option, if possible.

[robertisaar]

Nice, the PNs for the 7727. But if the price of those are comparable to the others, then you are looking at over $150 (IIRC) in just connector pieces. Seems like grabbing from the junkyard would be a better option, if possible.

sadly, that is very true...

luckily, a guy selling 7727 connectors on ebay was willing to get me some with at least 12" of wire sticking out of the plugs for the same price as he listed it for. comes out to like ~$22 with shipping.