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question about ALDL port for '94 Fleet

1519 Views 9 Replies 3 Participants Last post by  schlicky13
Nearly done with my Torqhead install and came across an anomaly that I don't know what to do about. Was looking at the instructions for wiring in the new OBD2 port in place of the original ALDL port and found an extra wire that isn't covered by Paul's instructions with his kit. I've emailed him as well, but wanted to see if anyone on here had any insight.

There's a dark green wire in cavity "J" that isn't mentioned anywhere in the instructions, and according to the FSM it's the dlc link to radio receiver. Wanting to know more info about where this wire goes or what it does, and whether I need to worry about it. Haven't dug too far into the FSM yet about it, so my answer may be in there, just haven't got the time right now and am hoping someone on here knows what to do with it.

Aside from putting the OBD2 port in, I'm down to finishing the routing of the plug wires around my headers, figuring out a mount for the new PCM, reconnecting the battery and then I should be able to test fire the motor before finishing up a few other loose ends.


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I am not sure how you are wiring this. The last "engine" swap I looked at had two plugs. One for the chassis(ABS, Air Bag, Climate Control, Radio. ECT) and one for the engine. Depending which connector the scanner connected to it could still diagnose car issues or read the new engine.

It can be impossible to convince a scanner to talk to OBD1 secondary computers when it sees a OBD2 engine computer.
Torqhead=24x conversion. It's not an engine swap, and this one is completely plug and play. You plug the Torqhead modified 0411 PCM into your factory wiring, ditch the Opti for the Torqhead unit that has crank and cam position sensors built into it, put on a different crank hub with an incorporated reluctor, plug an extra harness into the PCM for the LS coil packs, change knock sensors to ones compatible with the new PCM and away you go. If you want to be able to scan and tune you have to remove the old ALDL port and wire in an OBD2 port. Only real issue is that the Fleetwood isn't a true b-body and has some differences that Paul wasn't aware of, and this is another one I've come across.

As far as either of us know, nobody has put his kit on a Fleetwood yet, but we're both confident that the car will run and drive, but we may have to work out a few issues and depending on what we discover he may develop a kit unique to the d-body now that he's fully developed kits for the b, f and y bodies. My only question is what is that dark green wire for, since it seems to be unique to the Fleetwood, and what if anything will happen if I don't (or can't) incorporate it into the OBD2 port.
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I would expect that you can leave the green wire unconnected and test your engine.

Would you explain how the ABS and SIR will now work? They are connected in parallel to the old PCM communication wiring. If I understand you the com wires are now in a OBD2 port connected to a OBD2 PCM. Did Paul cover how the Torqhead scan and programming work with the other computers still on the com line. I assume he has tested this and there is no problem. B body conversions are usually OBD1 to OBD2 and have no problems I expect this is the same.

I am not trying to cause you worry but would like to know how all the OBD1computer systems will work in a OBD2 environment.
If I don't figure it out, that's probably what I'll do and see what happens. I doubt it's very important though, especially since I'm running an aftermarket stereo anyways. I can't really answer how the other systems work since he isn't very forthcoming on the specific details, however I suspect that's because it's proprietary and he doesn't want someone else copying his design. The best anyone has been able to come up with is that we know he has a custom bulkhead between the PCM itself and the connectors to the factory harness.

The conversion is known to be 100% working with all factory systems on the currently supported platforms (b, f and y bodies), but the d-body had a couple anomalies he didn't know about. The biggest being that it has a CCM, and none of the b-bodies have that. However, the y-body (Corvette's) also have a CCM and he has that version of his kit working completely in unison with the Corvette CCM. All factory functions on the Corvette function exactly as they should. The Corvette and Fleetwood use a different CCM though and handle different functions from one another, so I can't just use that kit. I've provided some info from the FSM on what the Fleetwood CCM handles, and while it is mostly autonomous from the PCM, should anything not function as it should he has assured me he can develop another version of his PCM that will work with it.

Also, the Corvette also had the same (or nearly the same) traction control system (the ASR system) as the Fleetwood, and again it is supposedly functioning just fine with the Corvette version of his kit. I wish I could be more specific, but the information just isn't publicly available as to what he's done to make them work. I do know from talking with him on the phone a few times though, that more often than not the other modules are usually only looking for very basic information, for example vehicle speed. And he can create a circuit in his bulkhead and/or make a tweak to his programming that will transmit the needed info through the correct wiring to the module in the same "format" as it would have been with the original PCM.

I do know from others and Paul himself that it is missing the integration for a couple minor emissions items, specifically the EGR and EVAP systems. He believes he has a way to make them function but has not worked on implementing that. Also it seems to me that someone on the gm-efi forum had a theory on how to get them functional as well, but to my knowledge no one has actually done it yet. Basically swap in LS compatible components (EGR valve, solenoids, etc.) and reactivate them in the tune.

In a few days I should know for sure, but the car should run and function mostly normal, I just need to find out what's missing or not functioning. I won't be surprised if I lose the traction control because I think the CCM sticks its nose into that (but I don't remember for sure), ABS might work since it's not too different from the b-body version, just a difference in number of channels but that should be handled by their respective modules. I'm curious what will happen with the HVAC system. It should function, but I might lose the ability to bring up DTCs and other info from the various modules on its display, won't know until I try. I'm not sure anyone with a Roadmaster has done the kit yet, so although he claims it works with all b-body systems, he may not have tried it on a car equipped with the digital HVAC system of the Roadmaster and Fleetwood.

There's definitely some questions to be answered, but as long as the car is driveable I'll be happy, and I can continue to work with him to iron out the kinks if there are any and get a specific PCM released that I can swap in to make everything work perfectly.
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The ABS may work but the traction control may not.

By memory your ABS sends info to the PCM to retard timing or reduce the injector volume when it does traction control.

I do not think you will retain the climate control diagnostics they are paired by programming in the PCM. A Caprice PCM will not talk to a RM CC unless it is reprogrammed.

If you ran a new com line to your PCM and just pined in com, ground, and +12V to the OBD2 you might be able to scan the body systems on your OBD1 plug.

It may be splitting hairs but I do not call it "plug and play" if features are lost in the conversion.

Please keep updating. I have not see a thread about Torqhead and any LT1.
There are a few threads on here about Torqhead (a couple started by me as I was doing research into it before I opted to buy it). It is plug and play on the other platforms, everything works as it should. The Fleetwood is an anomaly, but I was willing to be a guinea pig to see exactly what would happen. There are also a number of threads floating around some other forums, gm-efi, ls1lt1, and some f-body and corvette forums.

I figured as much on the HVAC stuff, as far as b-bodies go I think he primarily dealt with Caprice's and Impala's. Anything a little different or unique to the Roadmaster or Fleetwood needs to be found out so that he can deal with it. His product is still fairly new to the game, but in time I have no doubt it will be completely plug and play with everything that was LT1 equipped.

And in the interim he's also come out with some other neat stuff, including an alternator that will bolt right onto an LT1 as the factory one would, but allow you to use any aftermarket valve covers you want, no alternator notch required. I mean, how many people out there are still developing new tech for the old LT1 cars? I'm more than willing to support the guy.

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OK, so now that this thread has been completely and thoroughly hijacked, can we please get back to my original question: what exactly is the function of the dark green wire in cavity "J" of the ALDL port. Where does it go, what does it do, and can I live without it?


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I can't specifically find any info in Mitchell as for what exactly this does but it is only connected for radio data at the radio controller and radio receiver

Do you need it, likely not ,
What to do with it?
Put it in in # 14 of the OBD2 plug.
That is where it goes in a 96

Put the tan wire that was in M into # 9

Because of the half assed 1996 OBD2 systems , I found you can usually see all the data and do diagnostics of the "old car" through the newr plug.
Remember, the 1995 "F" body was OBD1 with an OBD2 plug

My 95 Caprice only has the OBD2 plug
I can talk to the ABS and Airbag fine by telling it the car is a 96
I talk to the engine by telling it it is a 06


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I'll do that if I don't hear anything different from Paul at Torqhead. And yes, his instructions move the tan wire to #9 in the new port. Pin B (white w/ black stripe) goes to Pin 2, Pin A (black w/white stripe) goes to Pin 5, and then add a ground and put it in Pin 4, and add constant +12v hot to Pin 16. On the f-bodies there's apparently also a wire in Pin G (black w/white stripe) and if equipped that goes to Pin 8. Not sure what that does or what the f-bodies have that b-bodies don't, but it's irrelevant for my application anyways.
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